WORKPLACE WELLNESS INTERVENTION STUDY
Charles P. Gerba1,2, Palomar Beamer2, Sonia L. M. Fankem1, Sherri Maxwell1, Kelly
Reynolds1,2, Kevin R. Plotkin2, Laura Y. Sifuentes,1 and Akrum H. Tamimi1
1
Department of Soil, Water and Environmental Science
College of Agriculture
2
Department of and Environmental Occupational Health
College of Public Health
University of Arizona
Tucson, AZ 85721
July 9, 2011
1
SUMMARY
The purpose of this study was to quantify the reduction of exposure to viruses after
introduction of a hygiene intervention. The non-pathogenic MS-2 and P-22 bacterial
viruses were used as models as they were a similar shape and size to human disease
causing viruses likely to be spread in the workplace. If these viruses were placed on
either the hand of one individual or one fomite (inanimate object) up to half or more of
the hands or surfaces in the office were contaminated within four hours. This illustrates
how important a contaminated fomite or hand can be in the spread of a virus in an office
environment. Shared facilities (break room, copy machine), where transfer of viruses
from infected to uninfected persons is most likely to occur were readily contaminated.
(50 to 60% of the surfaces).
The intervention of providing hand sanitizers and disinfecting wipes, and a short
instruction on their use along with proper signage on use resulted in statistically
significant reductions in the occurrence and concentration of the virus (MS-2) on hands
and fomites. This greatly reduced the spread of the virus in the office and reduced the
probability of infection by the common cold, flu and diarrhea viruses among office
employees by ~80%. This was achieved with only about half (52%) of the office
employees participating in the intervention
ATP measurements were also collected at adjacent sites to the virus sampling and
there was a significant correlation with virus reduction on fomites. This suggests that
reductions in ATP readings, can be used to monitor the success of the Health
Workplace Protocol. Thus measurements should be taken before an intervention and
after to assure that reductions have occurred. From the results of this study a 1/3
reduction in measurements below an instrument reading of 2 indicates that a significant
reduction in the spread of virus in the office has been achieved.
2
A. INTRODUCTION
Enteric and respiratory illnesses are readily spread among populations living and
working together. Common illnesses, such as colds and gastroenteritis have a
significant impact on health care costs and absenteeism among office employees.
Even if an employee is not absent significant losses in productivity can occur, these
costs may be equal or exceed those of absenteeism due to illness (8).
Office
environments have many communal areas, such as, break rooms, photocopying
machines, door entrances, restrooms, etc. that may serve as vehicles for the spread of
infectious diseases. In these enclosed environments fomites may be a route for the
spread of enteric and respiratory viruses (3). Fomites are contaminated by infected
individuals by either touching the surfaces or settling of droplets ejected during sneezing
or coughing. The viruses are then transferred to the hands of individuals touching these
surfaces and then transferred to the site of infection i.e. nose, mouth or eyes. Viruses
can survive on fomites anywhere from a few hours to a month (3). Face touching is
common in adults and occurs almost 16 times per hour (11).
Coliphage and virus DNA markers have been used to study the dispersion of viruses in
indoor environments, such as day care centers, neonatal nurseries and home settings.
Rheinbaben et al (15) applied the coliphage ΦX174 to the hands of volunteers and
doorknobs then traced the spread of the virus to surfaces and other people in the home
environment. Jang et al (7) placed cauliflower virus DNA on objects in day care centers
and found that it spread rapidly among toddlers. Oelberg et al (12) placed the same viral
DNA on telephones in a neonatal nursery hospital unit and found that it spread
throughout the unit over a seven day study period. Reynolds et al (13) used
fluorescence latex spheres the size of bacteria and viruses to trace their movement in
offices.
3
In another study, 14 people became contaminated with bacteriophage ΦX174 by
touching an experimentally contaminated door handle, the successive transmission
could then be followed up to the sixth contact person (14).
This study expanded on the study by Rheinbaben et al (15). We used phages P-22 and
MS-2 as virus tracers. The phages are similar in shape and size to many enteric and
respiratory viruses and are stable in the environment. The use of a bacterial virus tracer
also has the advantage over a chemical tracer in that die-off of the virus can be taken
into consideration as it spreads through a facility. The die-off of these viruses in the
environment is similar to that of human pathogenic viruses (3).
We gathered quantitative data on different surfaces and the amount of virus people
were exposed to for input into a quantitative microbial and human health risk
assessment model to predict the difference in probability of persons getting ill before
and after the Healthy Workplace Protocol intervention. The dynamic modeling approach
of Spicknall et al (17), Nicas and Jones (11), and Nicas and Best (10) were used as
models to predict probability of infection and the reductions in the number of infections
among the office employees. The models can also be used to quantify reduction in
exposure to any disease causing organisms via fomites/hands and the rate of spread of
a virus through the facility.
B. OBJECTIVES
The goal of this study was to use two bacterial viruses to trace their spread through an
office environment after contamination of hands and a selected fomite. This information
was then used to assess how rapidly the viruses spread and determine the probability
of infection of exposed individuals. These studies were repeated with a hygiene
intervention to determine the reduction in virus spread through the office and probability
of infection.
This study had several specific objectives:
4
1. To demonstrate that the Healthy Workplace Protocol1 (i.e. wiping desks in the
morning, hand sanitizer use after hand shaking, use of tissues) reduces
exposure to germs that cause illness. The goal was to substantiate the claim
“Studies have shown that using the Healthy Workplace Protocol reduces germs
that cause illness in the workplace.”
2. To demonstrate how germs that cause illness move through the workplace. The
goal was to substantiate the claim that “A study showed that a virus on an
employee’s hand at 8 AM spread to X % of the keyboards (or other objects in the
office by end of business day”.
3. To determine how many employees need to practice the Healthy Workplace
Protocol to result in a reduction in risk of illness among all employees in the
facility.
4. To determine if a correlation exists between ATP determination on surfaces and
bacteria numbers (specific to the Hygiena System).
C. MATERIALS AND METHODS
STUDY APPROACH
The overall aim of this study was to determine the spread of viruses onto fomites and
hands of employees in a typical office setting and an intervention designed to reduce
the exposure of employees to viruses. This was done by inoculating one of the viruses
on an entrance door push plate and the other on the hands on one of the employees.
After 4 and 8 hours hands of other office employees and various fomites in the office
were then tested to assess the spread of the virus throughout the office environment. In
one scenario MS-2 virus was added once to the door push plate and P-22 added three
times during the day to one person’s hand. In the second scenario the site inoculation of
the viruses was reversed i.e. MS-2 on the hands and P-22 on the door push plate)
1
Healthy Workplace Protocol = HWP
5
The viruses were inoculated onto the door push plate and hand with a swab. An area of
approximately 50 cm2 was contaminated with 6x109/cm2 of MS-2 virus or 6x108 P-22
virus. P-22 virus was inoculated at a lower level because it could not be grow to a titer
as high as MS-2. One hand was contaminated with the viruses and then the individual
was asked to rub their hands together so that both hands became contaminated. The
door push plate was only contaminated once during the day while the employees’ hand
was decontaminated three times during the day. The employees’ hand was inoculated
with 3x108 cm2 of MS-2 virus and 3x107/cm2 P-22 virus. To ensure that the selected
employee did not know their hand had been inoculated 21 other employees’ hands were
also inoculated with a placebo (phosphate buffered saline) at the same time. The
employees’ hand which was inoculated was selected at random.
Several fomites (54) were chosen throughout the office to be sampled and 22 volunteer
employee fingertips (thus 21 out of 80 employee hands were sampled) were tested at
the beginning of the day before the start of the study and after 4 and 7 hours after the
inoculation of the fomite and hand. The same employees and fomites were tested at
both 4 and 7 hours. No bacterial viruses were detected on the hands or fomites before
the beginning of the study (i.e. no background viruses).
Sterile cotton transport swabs containing neutralizing buffer (to neutralize any residual
disinfectant used on the surface or hand) (3M Corporation, St. Paul, MN) were used to
test the fomites and fingertips. The swab was aseptically removed and swabbed over
the sampled area of approximately 100 cm2 for fomites and 10 cm2 for fingertips . Both
hands of the subjects were tested with two different swabs. Each hand was sampled by
swabbing each finger with one swab (total of ~10 cm 2)
The data was statistically analyzed before and after log transformation using Excel 2010
(Microsoft Corporation, Seattle, WA) Because of the wide variability in bacteria data log
transformation is better representative of statistically relationships between data sets.
6
BACTERIAL VIRUSES
Coliphage MS-2 and P-22 were used in this study to represent pathogenic viruses in the
office environment. The surrogates for viruses in this study were MS-2 and P-22. MS-2
is a bacterial virus, which infects the bacteria E. coli and is very similar in shape and
size (23 nm) to rhinovirus, norovirus (most common cause of adult gastroenteritis) and
many other enteric viruses.
P-22 is a larger bacterial virus similar in size to
adenoviruses (~70 nm), which cause respiratory, eye, ear and gastrointestinal
infections.
MS-2 (ATCC 15597-B1 bacteriophage) was assayed by using the double-
layer agar technique with Escherichia coli ATCC 15597 as the host. The E. coli was
grown overnight, transferred to Tryptic Soy Broth (TSB) (Difco, Sparks, MD) and placed
for 3 hours at 37°C in a shaking water bath to reach the log growth phase. The virus is
produced by collecting it from an infected lawn of E. coli by addition of 6 mL of TSB and
then removing it with a pipette after 2 hours. The suspension was then centrifuged at
low speed to remove bacterial debris and stored at 5°C until needed.
Assay of bacterial virus P-22 (ATCC 19585-B1 bacteriophage) was grown and assayed
similar to MS-2, but the host Salmonella enterica (ATCC 19585) was used.
ASSESSMENT OF ATP AS AN INDICATOR
In addition to the bacterial viruses, Adenosine Triphosphate (ATP), the universal
energy molecule found in all animal, plant, bacterial, yeast, and mold cells was also
measured. ATP measurements were conducted with a Hygiena SystemSure™ ATP
meter (Camarillio, CA) and swabs provided by the manufacturer for sampling fomite
surfaces. Samples were collected in areas adjacent to the areas where the virus
samples were collected. ATP readings where compared before and after the
intervention and also to assess if any relationship existed between the readings and
virus occurrence.
7
OFFICE DESCRIPTION
The study was conducted in a relatively large office setting with approximately 80
employees being present every day. Prior to the large office study, a smaller scale
office (mean number of 15 participants) study was conducted in order to assess the
spread of virus and the applicability of the Healthy Workplace intervention. Once the
smaller study was completed, the large office setting (mean number of 80 participants)
was evaluated to assess the spread of virus and a hygiene intervention in a real world
scenario. The office was located on the second floor of a three story building. There
were three stairway accesses to the floor and one elevator access. The main entry door
to the floor is located near the elevator (persons exiting the elevator must enter through
the main door). There are separate men and women bathrooms located right outside
the main office near the elevator. To use the restroom an employee has to exit through
the main and then return through the same door. The entire office shares a common
kitchen area equipped with a microwave oven, a sink area, a coffee machine, and a
refrigerator. The office has several individual offices with doors located along the
windows, while the central area consisted of cubicles. There are seven locations
containing photocopy machines that are commonly shared.
The temperature inside the building averaged 23oC and relative humidity hovered
around 21 % for the duration of the study.
A diagram of the office can be found in Appendix C
D. STATISTICAL ANALYSES
A database was developed and all the collected data from the survey and the laboratory
analysis were entered. The data was plotted to determine if it followed a normal
distribution model. The log transformed data (log10) was normally distributed which
allowed us to perform the Analysis of Variance (ANOVA) with the assumption of normal
distribution. Excel 2010 (Microsoft Corporation) was used for the statistical analysis.
Multiple ANOVA tests were conducted on the data to test different hypotheses in order
8
to answer specific questions. Completely randomized designs were used to perform the
ANOVA with a rejection region of 5% using the F distribution.
E. RESULTS
SPREAD OF THE VIRUS ON FOMITES AND EMPLOYEES’ HANDS
The levels of P-22 found on fomites and hands were significantly lower than observed
for MS-2 probably because lower recovery, more rapid inactivation, and lower original
inoculums. As a result most of the discussion concerns the results obtained for the MS2 virus.
Before implementation of the Healthy Workplace Protocol, MS-2 spread to about 55% of
the fomites and employees’ hands sampled within four hours (Figure 1), after
inoculation of only one employee’s hand. This level of contamination remained virtually
unchanged after 7 hours. When the only the push bar was inoculated once at the
beginning of the day 48% of the employees hands and 43% of the fomites became
contaminated within 4 hours (Figure 2). After seven hours the virus could still be
detected on 26% of the hands and 13% of the fomites. These results demonstrate that
an infected employee who contaminates his hand during the day can spread the virus to
more than half the commonly touched fomites and fellow employee hands.
Contamination of just one communal surface also resulted in widespread contamination
of the office within four hours, although the number of surfaces contaminated decreased
after seven hours probably because of die-of of the virus and lack of recontamination,
as occurred when the hand was contaminated.
Implementation of the Healthy Workplace Protocol resulted in, an 82% reduction in
exposure to the virus (hand and fomite occurrence combined), when a hand was
originally inoculated with the MS-2 (Figure 1 vs. 3).
After 7 hours the number of
contaminated fomites and hands increased, but was still half more that observed on the
hands and fomites before the intervention (Figure 1 vs. 3). When the door push plate
9
was contaminated there were 63% fewer hands contaminated and 70% fewer fomites
contaminated after 4 hours. After 7 hours there was 50% fewer viruses were detected
on fomites, and 13% fewer hands contaminated (Figure 2 vs. 4). Thus, overall there
was a significant reduction in virus occurrence on hands and fomites if either a hand or
fomite was the original source of contamination.
Percentage
FIGURE 1: Percentage of MS-2 and P-22 contaminated hands and fomites at T=4
hrs and T=7 hrs. Non-intervention (Study #5) on 04/29/11.
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
63%
52% 56%
8%
6%
0%
T=4hrs
50%
0%
T=7hrs
P-22
Employees with contaminated hands
T=4hrs
T=7hrs
MS-2
Contaminated fomites
10
FIGURE 2: Percentage of MS-2 and P-22 contaminated hands and
fomites at T=4 hrs and T=7 hrs. Large non-intervention (Study #6)
on 05/03/11
FIGURE 3: Percentage of MS-2 and P-22 contaminated hands and fomites at T=4
hrs and T=7 hrs. Large intervention 1 (Study #7) on 05/06/11
100%
90%
80%
Percentage
70%
60%
50%
40%
30%
30%
20%
10%
17%
11%
10% 9%
5%
5%
T=4hrs
T=7hrs
0%
0%
P-22
Employees with contaminated hands
T=4hrs
T=7hrs
MS-2
Contaminated fomites
11
FIGURE 4: Percentage of MS-2 and P-22 contaminated hands and fomites at T=4
hrs and T=7 hrs. Large intervention 2 (Study #8) on 05/10/11
100%
90%
80%
Percentage
70%
60%
50%
40%
30%
18%
20%
10%
0%
7%
20%
13%
6%
6%
0%
0%
T=4hrs
T=7hrs
P-22
Employees with contaminated hands
T=4hrs
T=7hrs
MS-2
Contaminated fomites
IMPACT OF INTERVENTION ON VIRUS CONCENTRATION ON FOMITES
The geometric means (Geo Mean) and the corresponding standard deviations (St. Dev)
of the MS-2 and P-22 virus concentrations on the fomites are shown in Table 1 after
four hours. There was a significant statistical difference between MS-2 concentration
before intervention and 4 hours after intervention with a p-value of 0.000067. However,
no significance difference was found for the concentration of P-22 as shown in Table 2.
This can be explained by much lower levels of P-22 detected (see Table 2).
12
TABLE 1: Virus concentrations (per cm 2 ) on fomites and hands
before and after intervention (4 hours)
Log (MS-2)
Log (P-22)
Before
After
Before
After
Intervention Intervention
Intervention Intervention
Number of
Samples
(N)
108
108
108
107
Geo mean
-0.30
-0.70
-0.76
-0.76
St. Dev
0.82
0.64
0.56
0.44
TABLE 2: Is there a significant difference between virus
numbers before and after intervention at T=4hours?
Coliphage
Answer to the question
p-value
MS-2
Yes
0.000067
P-22
No
0.990396
Using the 5% rejection region for the ANOVA test, the concentrations of MS-2 (Table 4)
was marginally significant after a 7 hour workday for MS-2 (p-value = 0.054), but not for
P-22 as shown in Table 4.
13
TABLE 3: Virus concentrations (per cm 2 ) on fomites and hands
before and after intervention (T=7 hours)
Log (MS-2)
Statistic
Log (P-22)
Before
After
Before
After
Intervention
Intervention
Intervention
Intervention
N
108
108
107
108
Geo mean
-0.36
-0.59
-0.85
-0.81
St. Dev
0.94
0.78
0.24
0.34
TABLE 4: Is there a significant difference between virus
numbers before and after intervention after T=7 hours?
Coliphage
Answer to the question
p-value
MS-2
No
0.0543
P-22
No
0.3148
When the data from sampling at T=4 hours and T=7 hours were combined, the impact
of the intervention was highly significant for reducing the exposure to MS-2, but not for
P-22 as shown in Tables 5 and 6.
TABLE 5: Virus concentrations (per cm 2 ) on fomites and hands before and
after intervention (T=4 hrs and T=7 hrs), and ATP readings.
Log (MS-2)
Statistic
Log (P-22)
Log (ATP)
Before
After
Before
After
Before
After
Intervention
Intervention
Intervention
Intervention
Intervention
Intervention
N
216
216
216
216
54
54
Geo mean
-0.33
-0.65
-0.78
-0.78
-0.91
-1.23
St. Dev
0.88
0.72
0.54
0.42
0.55
0.51
14
TABLE 6: Is there a significant difference between virus concentration
before and after intervention for all data (T=4 hours and T=7 hours
combined)? Is there a significant difference between ATP readings and MS 2 virus occurrence and MS-2 virus?
Indicator
Answer to the question
p-value
MS-2
Yes
0.000047
P-22
No
0.843661
ATP
Yes
0.002317
IMPACT OF INTERVENTION ON THE OCCURRENCE OF VIRUS
CONTAMINATED FOMITES AND ATP MEASUREMENTS
Table 5 shows the geomean of ATP readings vs. the geomean of MS-2 and P-22 on the
studied fomites. Appendix E, Figure E7 shows the different cumulative probabilities for
the concentration of the viruses and ATP readings after 4 and 7 hours, before and after
the intervention. Figure E7 can be used to determine the probability of a fomite having a
virus concentration of less than X PFU/cm2 before intervention and after intervention
after 4 and 7 hours.
The number of sites with an ATP reading of greater than 2 was 45% before intervention
and 15% after the intervention. This was statistically significant (Table 6). Thus, ATP
readings could be used to determine the success of the intervention in terms of MS-2
virus reduction and exposure to the virus. They could not, however, be used to
determine the concentration of the viruses on fomites (Appendix F).
REDUCTION IN PROABILITY OF INFECTION
15
The predicted mean hand concentration of the MS-2 phage at steady state, the mean
expected dose of MS-2 to target membranes (nose, eyes, mouth) and the expected risk
of infection for influenza, rhinovirus, rotavirus and norovirus were calculated based on
the methods in Nicas and Best (10).
The predicted mean hand concentration at steady state, Chand,T (viable phage per cm2) is
calculated according to:
j m
Chand,T 
 H
j 1
surface, m
A

 f12,m  Csurface surface 
A
 hand 
(1)
nk

H orifice,k  Aorifice,k  


A


surface

  f 23 n 1
T    dieoff  H surface f 21  


Ahand
 Ahand 




Where Csurface is the concentration of phage on fomites (viable phage per cm 2), Hsurface is
the rate of hand to fomite contacts (contacts per minute), H orifice
is the contact
frequency of hands to the orifice (i.e., eyes, nose, mouth) (contacts per minute), f 12 is
the fraction of the phage transferred from fomites to the hands. f 21 is the fraction of the
phage transferred from the hands to fomites, f23 is the fraction of phage transferred from
the hand to the target orifice, Asurface is the surface area touched per hand contact with
fomite surface (cm2), Ahand is the total surface area of the hand (cm2), Aorifice is the
contact area between the hand and the target orifice (cm 2), and αdieoff is the constant
rate of MS-2 die-off (fraction per minute). Asurface/Ahand is the fractional surface area
(FSA).
The decay constant, λ, is calculated according to the equation below:
nk
   dieoff  H surface
 Asurface
 f 21  
 Ahand

  f 23

 H
n 1
orifice , k
 Aorifice ,k 
Ahand
When T>>1/λ, the phage concentration on the hands are at steady state (10). After four
hours or T = 240 minutes, λMS2 has a mean of 1.2. Therefore, T>>1/λ, and the
concentration of phage on the hands is at steady state.
16
The dose of viable phage to each orifice, DT is calculated, based upon the steady state
hand concentration, using the following equation:
DT = Chand,T  f 23  T  H orifice Aorifice
Finally, the risk can be calculated using different host susceptibility, α, and the total
dose of phage that is delivered to the target orifice using the following equation:
R  1  exp   Dtotal .
Where Dtotal is the total dose of MS-2 phage delivered to all relevant orifices, depending
upon the pathogen.
When selecting the appropriate activity parameters, Hsurface and f12 varied by surface
type. They were divided into smooth and textured surfaces. A smooth surface would
consist of hard materials like wood while a textured surface consisted of materials like
denim or cloth. The Horifice and the Aorifice were also separated by type. The orifices
examined were the eyes, nose and mouth. The parameters used for contact rate and
surface area are in Table 8.
The MS-2 die-off constant and the MS-2 transfer
efficiencies are located in Table 9.
TABLE 8: Activity parameters
Parameter
Distribution
Units
Source
Hsurface,smooth
LN(1.4,0.45)
Contacts/hour Beamer et al. (2011)(2)
Hsurface,textured
LN(1.7,0.43)
Contacts/hour Beamer et al. (2011)(2)
Hmouth
LN(-1.7,1.2)
Contacts/hour Beamer et al. (2011)(2)
Heyes
LN(-2.9,1.2)
Contacts/hour
Hnose
LN(-4.6,4.2)
Contacts/hour
Asurface
(FSA)
LN(-1.9,0.15)
Notes
Nicas and Best
(2008)(10)
Nicas and Best
(2008)(10)
AuYeung et al.
Fractional, must
(2008)(1)
multiply by Ahand
17
Ahand
cm2
U(890-1070)
Mean for males
EFH, 2009
and females
2
-
(estimate)
(estimate)
Aeye
U(0.1-2)
cm
Anose
U(0.1-10)
cm2
-
Amouth
U(1-41)
cm2
Leckie et al. (2000)(9)
* lognormal, LN (lognormal mean, standard deviation); uniform distribution, U(minimum, maximum)
TABLE 9: Model phage parameters
Parameter
Distribution
Source
Notes
f12,smooth
U(0.015-0.22)
Gerba (2011)(4)
Appendix H
f12,textured
U(0.0003-0.0042)
Gerba (2011)(4)
Appendix H
f21
U(0.015-0.22)
Gerba (2011)(4)
Assumed smooth
f23
0.339
Rusin et al. (2002)(16)
U(5.1x10-4-1.0x10-5)
Gerba (2011)(4)
αdieoff
Appendix I
*lognormal, LN(lognormal mean, standard deviation); uniform distribution, U(minimum, maximum). f23 was treated as a constant
Since not all pathogens infect all membranes equally, appropriate target membranes
were selected for calculating risk. For rotavirus and norovirus, the dose administered
to the mouth was used to model the risk.
For rhinovirus and influenza, the dose
administered to the nose and the eyes were combined to calculate risks.
TABLE 10: Infection parameters for selection human respiratory and
enteric viruses
Parameter
Source
αnorovirus
0.039
Yezli and Otter (2007)(19)
αrotavirus
0.25
Haas et al. (1999)(5)
αrhinovirus
0.2
Hendley et al. (1972)(6)
αinfluenza
0.69
Teunis et al. (2010)(18)
The concentration of phage on the hand was calculated using Equation 1 and the
concentration of phage measured on fomite surfaces during the baseline trials as well
18
as the post intervention trials. Monte Carlo simulations were used to address
environmental variability and experimental uncertainty. The fomite measurements and
the parameter distributions (Table 8 and Table 9) were randomly sampled to generate
1000 iterations of the estimated phage concentration on hands. The estimated values
were compared to the phage concentration measured on the hands during each trial.
The modeled estimates and the measured phage concentrations on the hands were
not statistically different.
By using the fomite concentrations from each trial (i.e., baseline and intervention), risk
were calculated using simulated hand concentrations to assess the efficacy of the
intervention. The intervention had a significant effect for reduction of risk (Figure 5),
where p<0.001 for all viruses modeled.
FIGURE 5: Modeled mean, standard deviation and mean percent reduction
of risks at baseline and post intervention
19
During the course of this investigation, it was determined that it is possible to model the
expected concentration of phage found on the hand from the concentration of phage
present on the fomites. In the future, this model could be used to assess exposures
and various risks of infection for phage found in an office setting at environmental
levels which are below the current limit of quantification of viral plaque assays.
F. DISCUSSION AND CONCL USIONS
The results of this study have shown statistically significant reductions in spread of virus
(MS-2) from either a contaminated hand or fomite throughout an office environment. It
was shown that even if a commonly touched fomite (office door bar) was contaminated
once that the virus spread throughout the office contaminating half of the fomites
studied. This illustrates how important a contaminated fomite in an office environment
can result in the spread of a virus throughout a facility. Shared facilities (break room,
copy machine), where transfer of viruses from infected to uninfected persons is most
likely to occur were readily contaminated.
The intervention of providing hand sanitizers and disinfecting wipes, and a short
instruction on their use along with proper signage on use resulted in statistically
significant reductions in the occurrence and concentration of the virus on hands and
fomites. This reduced the spread of the virus in the office and reduced the probability of
infection by common cold, flu and diarrhea viruses among office employees by ~80%.
Contaminated hands seem to drive the spread of the virus (MS-2) more than a
contaminated fomite. When hands were contaminated, the odds of recovering MS-2
post-intervention were lower than the odds of recovering MS-2 in the
before the
intervention group (Data not shown).
It should be pointed out that these results were achieved considering that not all
individuals (52.5% participation rate, 42 out of 80) working in the office building
participated in the intervention; the intervention was only in place for a short period of
time (three working days). Greater reductions might be achieved by assigning a person
20
to disinfect communal areas on a regular basis during the day and more formal
instruction on the hygiene protocol than we provided during the course of this study.
Although there was no marked difference in the number of contaminated personal
fomite sites versus communal fomites sites, after the implementation of the intervention
more personal fomites were contaminated than communal fomite sites. Every employee
was provided with the necessary materials for the intervention along with “how to”
forms. Flyers were also posted in the common areas along with disinfecting wipes,
Kleenex and sanitizing wipes. Given this result and the questions asked by study
participants, we suggest a few changes to the Healthy Workplace Protocol such as a
more details description of the protocol. Participants should be told how many times in a
day for example, their work area needs to be cleaned.
ATP measurements were also collected at adjacent sites to the virus sampling and
there was a significant correlation with virus reduction. This suggests that while ATP
measurements may not be able to predict the occurrence or concentration of bacteria or
virus reductions, it can be used to monitor the success of the Health Workplace
Protocol. Thus measurements should be taken before and after an intervention to
assure that the protocol is being adhered to.
In conclusion, the results of this study show that the Healthy Workplace Protocol can
result in a significant reduction in virus contaminated work places and probability of
infection from viruses which cause respiratory and enteric infections.
POSSIBLE CLAIMS ABOUT THE HEALTHY W ORKPL ACE PROTOCOL
The Healthy Workplace Protocol reduces (using MS-2 virus data):

The probability of infection for viruses which cause respiratory infection
(common cold and influenza) and diarrhea (norovirus and rotavirus) was
reduced by approximately 80% (Figure 5).
21

The number of persons who could become infected with influenza decreased
from 35% to 7% (Figure 5).

The number of surfaces containing a virus was significantly reduced; from
56% to 9% after 4 hours (Figures 1 and 3) and from 13% to 6% after 7 hours
(Figures 2 and 4). Or a 84% reduction in virus contaminated surfaces
occurred after 4 hours and 45% after 7 hours.

The number of items/fomites contaminated with viruses was reduced by 62%
(Figures 2 and 4).

The number of people with viruses on their hands was reduced in half (50%)
(Figures 1-4). The occurrence of viruses in communal work areas was
reduced by more by more than 80% after four hours and by 70%-100% after
seven hours (Appendix G).

The occurrence of viruses on commonly touched objects (telephone,
computer mouse, desktop) in personal work areas was reduced by more than
50% after four hours and by 25% after eight hours (Appendix G)

The spread of viruses on hands and commonly touched objects (Appendix G)
in the office environment was reduced by more than 60%.

The spread of viruses on fomites and people’s hands in the office was
significantly reduced throughout the work day. The spread of viruses on the
hands and commonly touched objects in the office environment was reduced.
Claims regarding rapid contamination potential (intervention needs assessment):

Within 4 hours, viruses spread to 43% to 56% (~1/2) of the fomites in the
office (Figures 1 and 2)

Within four hours, 50% of employees’ hands were contaminated (Figures 1
and 2). Seven hours after the start of the workday, 26% to 50% of employees
hands were contaminated (Figures 3 and 4).
22
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24
APPENDIX A
TABLE 1A: LARGE STUDIES DETAILS (STUDIES #5 - 8)
Date
Study
type
Phages
(initial
concentration
per cm2)
Inoculation
time
P-22
(6x108)
Phage
P-22
Surfaces
inoculated
04/29/11
9:30am
MS-2
(3x108)
Temp
(°C)
Hum
(%)
(T=4hrs)
23.1
21.0
3pm
23.0
20.0
(T=4hrs)
23.0
21.0
3pm
23.0
19.0
Employee’s hands
MS-2
(T=1.5hr)
10:30am
(hours after
initial
inoculation)
12pm
MS-2
Non
Intervention
Environmental
Conditions
Main door outside
handle
8am (T=0hr)
Study
#5
Hour of
sample
collection
Employee’s
MS-2
hands
MS-2
Main door outside
handle
(T=7hrs)
(T=2.5hrs)
MS-2
(6x109)
Study
#6
05/03/11
8am
12pm
P-22
Non
Intervention
9:30am
P-22
(3x107)
P-22
(T=1.5hr)
10:30am
Employee’s hands
P-22
Employee’s
hands
(T=7hrs)
(T=2.5hrs)
25
P-22
8am (T=0hr)
Study
#7
12pm
P-22
(6x108)
05/06/11
MS-2
Intervention
MS-2
(3x108)
9:30am
(T=1.5hr)
10:30am
(T=2.5hrs)
Employee’s
MS-2
Study
#8
8am (T=0hr)
Intervention
P-22
(3x107)
23.8
19.0
3pm
23.0
19.0
(T=4hrs)
23.2
24.0
3pm
22.8
23.0
(T=7hrs)
hands
Main door outside
handle
12pm
P-22
05/10/11
(T=4hrs)
Employee’s hands
MS-2
MS-2
MS-2
(6x109)
Main door outside
handle
9:30am
P-22
(T=1.5hr)
10:30am
Employee’s hands
P-22
Employee’s
hands
(T=7hrs)
(T=2.5hrs)
26
APPENDIX B
TABLE 1B: List of communal and personal office area fomites
PERSONAL FOMITES (N=16)
Chairs Armrests
Computer Mouse
Desktops
Keyboards
Phones
COMMUNAL FOMITES (N=36)
Bathroom Flush Handles
Light Switch
Kitchen area Faucet
Bathroom Door Outside handle
Bathroom Door Inside handle
Bathroom Faucet Handle
Coffee Pot Handles
Conference Room Chairs
Conference Room Doorknob In
Conference Room Doorknob Out
Conference Room Table
Door Outside Handle
Door Inside Handle
Drinking Fountain "button"
Elevator Button 2nd Floor
Fridge Handle
Microwave buttons
Printer Buttons
Printer Table
Table
Three Hole Punch
27
APPENDIX C
FIGURE 1C: Map of large office
Men’s bathroom
Door 1
Women’s bathroom
Main door
Door 2
Door 3
28
APPENDIX D
Healthy Workplace Protocol (HWP)
Protocol:
1. Sanitize your hands when entering work each morning and when leaving each
evening.
2. Sanitize your hands before and after shaking hands, after touching frequently
touched surfaces, and after touching your nose or face.
3. Use tissue to wipe or blow your nose.
4. Wash hands for 15 seconds with soap and dry with a clean paper towel after
using the restroom and before eating food.
5. Use disinfecting wipes to wipe down your keyboard, mouse, phone, and desk
at the beginning of each day.
6. Use disinfecting wipes to wipe down the conference room table before starting
a meeting.
7. Use sanitizing wipes to wipe down frequently touched items in the break room
like refrigerator handles, microwave handles and buttons, coffee pot handles,
vending machine buttons, and tables.
Offices:
1. Hand Sanitizer with Bacteria Kill Claim FDA‐Approved (KIMTECH*
Moisturizing Instant Hand Sanitizer)
2. Surface Disinfecting Wipes with Virus & Bacteria Kill Claim EPA‐Approved
(HWP Good & Clean Disinfecting Wipes)
3. Basic Facial Tissue (KLEENEX* Tissue)
Restrooms:
4. Basic Hand Soap that is not anti‐bacterial
5. Paper Towels
Communal Areas:
6. Hand Sanitizer Stands/Dispensers with Bacteria Kill Claim FDA‐Approved
(KLEENEX* Moisturizing Instant Hand Sanitizer)
29
7. Break Rooms ‐ Food safe sanitizing wipes with Bacteria Kill Claim
PA‐Approved (KIMTECH PREP* Surface Sanitizer Wipes)
8. Conference Rooms
a. Hand Sanitizer with Bacteria Kill Claim FDA‐Approved (KIMTECH*
Moisturizing Instant Hand Sanitizer)
b. Surface Disinfecting Wipes with Virus & Bacteria Kill Claim
EPA‐Approved (HWP Good & Clean Disinfecting Wipes)
c. Basic Facial Tissue (KLEENEX* Tissue)
30
APPENDIX E
DISTRIBUTION OF MS-2 AND P-22 ON FOMITES BEFORE AND AFTER THE
INTERVENTION
FIGURE 1E: MS-2 distribution on fomites before and after intervention after 4
hours
FIGURE 2E: MS-2 distribution on fomites before and after intervention after 7
hours
31
FIGURE 3E: MS-2 distribution on fomites before and after intervention after 4 and
7 hours combined.
FIGURE 4E: P-22 distribution on fomites before and after intervention after 4
hours
32
FIGURE 5E: P-22 distribution on fomites before and after intervention after 7
hours
FIGURE 6E: P-22 distribution on fomites before and after intervention after 4 and
7 hours combined.
33
FIGURE 7E: ATP measurements before and after intervention.
34
APPENDIX F
DOES A CORRELATION EXIST BETWEEN ATP READINGS AND THE PRESENCE OF MS2 AND P-22 DETECTION ON FOMITES?
No statistically significant relationship was found between the occurrence of the
bacterial viruses and ATP readings even after the data was log transformed.
FIGURE 1F: ATP vs. MS-2
35
FIGURE 2F:
ATP vs. MS-2 – Log Scale
36
FIGURE 3F: ATP vs. MS-2 – Log Transformed Data
37
APPENDIX G
SCENARIO 1 ---- Week 5 & 7
 One fomite (main door outside handle) contaminated with P-22 at the beginning of the day (8am, T=0 hr)
 One employee’s hands contaminated three times (8am, 9:30am, and 10:30am) with MS-2
TABLE 1G: Percentage of MS-2 and P-22 contaminated fomites - Scenario 1 (Study#5 & Study#7)
T= 4Hrs
Personal
fomite sites
Positive
N
(%)
18 10(55.6)
Pre-Intervention
Communal
All sites
fomite sites
Positive
Positive
N
N
(%)
(%)
36
20(55.6)
54
30(55.6)
Personal
fomite sites
Positive
N
(%)
18 3(16.7)
T= 7Hrs
18
12(66.7)
36
22(61.1)
54
34(63.0)
18
T= 4Hrs
18
3(16.7)
35
0(0.0)
53
3(5.7)
T= 7Hrs
18
0(0.0)
35
0(0.0)
53
0 (0.0)
Intervention
Communal fomite
sites
All sites
N
Positive (%)
N
36
2(5.56)
54
Positive
(%)
5(9.3)
9(50.0)
36
7(19.44)
54
16(29.6)
18
1(5.6)
35
4(11.43)
53
6(11.3)
18
0(0.0)
35
0(0.00)
53
0(0.0)
MS-2
P-22
38
FIGURE 1G: Percentage of MS-2 contaminated hands and fomites at T=4 hrs and T=7 hrs. Scenario #1
(studies #5 &7)
39
SCENARIO 2 ---- Week 6 & 8
 One fomite (main door outside handle) contaminated with MS-2 at the beginning of the day (8am, T=0 hr)
 One employee’s hands contaminated three times (8am, 9:30am, and 10:30am) with P-22
TABLE 2G: Percentage of MS-2 and P-22 contaminated fomites - Scenario 2 (Study#6 & Study#8)
T= 4Hrs
Non-Intervention
Personal fomite
Communal
sites
fomite sites
Positive
N Positive (%)
N
(%)
18
7(38.9)
35
16(45.7)
53
Positive
(%)
23(43.4)
T= 7Hrs
18
3(16.7)
35
4(11.4)
53
7(13.2)
18
T= 4Hrs
18
3(16.7)
36
0(0.0)
54
3(5.6)
T= 7Hrs
18
1(1.6)
36
1(2.8)
54
2(3.7)
All sites
N
Intervention
Communal
fomite sites
Positive
N
(%)
35
3(8.6%)
53
Positive
(%)
7(13.4)
3(16.7)
35
0(0.0%)
53
3(5.7)
18
3(16.7)
36
1(2.8%)
54
4(7.41
18
3(16.7)
36
0(0.0%)
54
3(5.6)
Personal fomite
sites
Positive
N
(%)
18
4(22.2)
All sites
N
MS-2
P-22
40
FIGURE 2G: Percentage of MS-2 contaminated hands and fomites at T=4 hrs and T=7 hrs. Scenario #2
(studies #6 &8)
41
APPENDIX H
Percent of MS-2 virus transfer from finger to fomite on different fomite surfaces.
To determine the transfer of MS-2 to and from various fomites MS-2 virus was added to
different fomite surfaces and then a finger was press against the surface at a define
pressure and time. The virus concentration on the surface before and the finger after
touching was used to determine the percentage of virus transferred. The methods for
this protocol are described in detail in Ansari, S. A. et al. 1988. Rotavirus survival on
human hands and transfer of infectious virus to inanimate and nonporous inanimate
surfaces. J. Clin. Microbiol. 26:1513-1518.
FIGURE 1H: Fomite to finger transfer data for MS-2 and P-22 ( b l ue
=c o lum ns r e la t i ve hum i di t y of 40 t o 6 0% . R e d c o lum ns r e l at i v e h u m idi t y = 2 0 t o 30 %)
42
APPENDIX I
Survival of MS-2 and P-22 on fomites (Formica & stainless steel).
The virus was added to the selected surfaces and then the surfaces sampled using a
swab after the time periods indicated. Methods are described in detail in Henley, J. B.
2008. Determining inactivation rates of viruses on indoor surfaces. Ms. Thesis.
University of Arizona, Tucson, AZ. The inactivation data for P-22 is shown in Figure 1l.
The inactivation rate used for MS-2 was from Henley (2008) Table 8 of the thesis.
Figure 1I. P-22 Survival on Formica and Stainless Steel
Time
(min)
Temperature
(°C)
Humidity
(%)
PFU/ml
Formica
0
30
60
120
180
240
21.6
22.9
23.2
23.3
23.4
23.4
22
20
19
20
19
20
3.50E+08
4.30E+06
5.30E+06
5.20E+06
3.60E+06
2.24E+06
Stainless
Steel
2.40E+07
1.05E+07
4.80E+06
2.54E+06
1.88E+06
1.00E+06
Log Reduction
Formica
Stainless
Steel
0.00
1.91
1.82
1.83
1.99
2.19
0.00
0.36
0.70
0.98
1.11
1.38
Note: Seeded at 3.6 E+11 PFU/mL
43
APPENDIX J
FIGURE J1: Reduction of MS-2 virus by on hands by Kimcare hand sanitizer.
MS-2 virus was added to the fingertips of each hand at the concentration shown. The
hands were then treated with Kimcare hand sanitizer and retested again for the virus.
The hand sanitizer was capable of reducing the virus on the hands by an average of
74.8%.
44
45