“First-person view” of pathogen transmission and hand hygiene – use of a new head-mounted video capture and coding tool
Clack et al. Antimicrobial Resistance and Infection Control
“First-person view” of pathogen transmission and hand hygiene - use of a new head-mounted video capture and coding tool
Lauren Clack 0
Manuela Scotoni 0
0 Equal contributors Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich , Raemistrasse 100, CH-8091 Zurich , Switzerland
Background: Healthcare workers' hands are the foremost means of pathogen transmission in healthcare, but detailed hand trajectories have been insufficiently researched so far. We developed and applied a new method to systematically document hand-to-surface exposures (HSE) to delineate true hand transmission pathways in real-life healthcare settings. Methods: A head-mounted camera and commercial coding software were used to capture ten active care episodes by eight nurses and two physicians and code HSE type and duration using a hierarchical coding scheme. We identified HSE sequences of particular relevance to infectious risks for patients based on the WHO 'Five Moments for Hand Hygiene'. The study took place in a trauma intensive care unit in a 900-bed university hospital in Switzerland. Results: Overall, the ten videos totaled 296.5 min and featured eight nurses and two physicians. A total of 4222 HSE were identified (1 HSE every 4.2 s), which concerned bare (79%) and gloved (21%) hands. The HSE inside the patient zone (n = 1775; 42%) included mobile objects (33%), immobile surfaces (5%), and patient intact skin (4%), while HSE outside the patient zone (n = 1953; 46%) included HCW's own body (10%), mobile objects (28%), and immobile surfaces (8%). A further 494 (12%) events involved patient critical sites. Sequential analysis revealed 291 HSE transitions from outside to inside patient zone, i.e. “colonization events”, and 217 from any surface to critical sites, i.e. “infection events”. Hand hygiene occurred 97 times, 14 (5% adherence) times at colonization events and three (1% adherence) times at infection events. On average, hand rubbing lasted 13 ± 9 s. Conclusions: The abundance of HSE underscores the central role of hands in the spread of potential pathogens while hand hygiene occurred rarely at potential colonization and infection events. Our approach produced a valid video and coding instrument for in-depth analysis of hand trajectories during active patient care that may help to design more efficient prevention schemes.
Video; Transmission risk; Hand hygiene; Observation
Healthcare-associated infections, including surgical site
infections, ventilator-associated pneumonia, urinary tract
infections, and catheter-associated bloodstream infections,
prolong length of hospital stay and increase cost,
morbidity and mortality [
]. Additionally, antibiotic resistance
is emerging worldwide as a serious health threat [
Transmission of potential pathogens between patients
occurs primarily via healthcare worker (HCW) hands
when hand hygiene (HH) is omitted at critical moments
]. Such hand-to-surface exposures (HSE) occur
frequently , resulting each time in a bi-directional
exchange of microorganisms between the hand and the
touched surface [
]. In consequence, hands transport
microorganisms sequentially between surfaces [
Depending on the nature of the microorganisms and of the
receiving surface, this can result in patient harm. If
microorganisms feature antibiotic resistance, their
transmission to a patient can result in prolonged carriage. If
the microorganisms are virulent and the receiver surface
is a skin lesion or an invasive device such as a central
venous line, the transmission may result in
Several studies show that infectious microorganisms
can survive on human skin long enough to be
crosstransmitted and that hand hygiene using alcohol-based
handrub is an effective way to decrease this transmission
]. With the WHO “My five moments for hand
hygiene”, a user-centered concept based on education,
training, monitoring and reporting of hand hygiene has
been introduced with the goal to bridge the gap between
scientific evidence and daily healthcare practice .
Yet, HCWs still fail to consistently apply hand hygiene.
The lack of awareness regarding what people touch
during their routine work may play an important role in this
failure to adhere to established rules [
]. Today’s gold
standard to monitor HH performance consists of direct
observation of healthcare workers by trained observers
during patient care [
]. This method may not
capture every HSE during fast-paced care and thus,
underestimates the true risk of pathogen transmission
]. On the other hand, automated electronic hand
hygiene monitoring systems still fall short of detecting
all hand hygiene opportunities [
To better understand the nature of microbial
handtransmission in a real-life intensive healthcare setting, we
built and pilot-tested a new observation and coding
system that would consistently capture every HSE, and thus
allow to study true transmission risks via HCWs’ hands.
Setting up and offsite-testing of the system
We opted for a mobile, head-mounted action camera
(GoPro® Hero 4 Black edition, GoPro Inc., San Mateo,
CA) worn by HCW during patient care. The camera was
positioned on the forehead of the HCW by means of a
head-strap and was oriented facing slightly downwards.
With the help of an iPad mini (Apple, Cupertino, CA)
the researcher could control the optimal orientation of
the camera through a Wi-Fi connection. The camera
was oriented to keep the participant’s hands in its visual
field. In a first round, we tested and adjusted the camera
in the medical high-fidelity simulator of our institution.
After resolving all technical issues, we proceeded to
videotape real-life care activity in three intensive care units
(ICUs) specialized in trauma, cardiology, and visceral
surgery at the University Hospital Zurich (USZ), Switzerland.
The USZ is a 900-bed university-affiliated tertiary care
center with a well-established infection prevention and
control (IPC) group, weekly IPC rounds, and a designated
IPC nurse consultant for each hospital ward.
Participants and onsite-use of the system
A convenience sample of 10 participants was recruited
among ICU nurses and physicians. Each participant
wore the head-mounted camera during his/her morning
shift for about 70 min. Morning shifts were chosen
purposefully to guarantee that patient care activity took
place. Subsequently, HCW continued their care activity
without further interruptions by the researcher, who left
The videos were exported from the camera and stored
on a secured server. Episodes of ~30 min direct patient
care were purposefully selected from each of the 10
videos for further processing. Within each of these video
episodes, the occurrence, duration, and type of every
HSE was systematically coded by a trained coder (MS)
and supervised by a second person (LC) using the
behavioral observation software INTERACT® (Mangold
international, Arnstorf, Germany) together with a
structured, hierarchical coding system (Fig. 1).
The observation and coding system aimed to capture
the duration and nature of all HSE, defined as contact
between the observed healthcare worker’s hand and any
other surface. The hierarchical coding system consisted
of 4 levels, of which the first two indicate the nature of
the hand (gloved vs. bare and right vs. left), and the
latter two indicate the nature of the surface (location
relative to patient zone and type of surface) involved in the
hand-to-surface exposure (Fig. 1). In line with the WHO
patient zone concept [
] and observation method [
the third coding level distinguished between surfaces
“inside patient zone”, “outside patient zone”, and “critical
sites”. “Inside patient zone” was defined as the patient
him−/herself and all items in the immediate
environment likely to be colonized with patient flora [
“outside patient zone” contained other patients with
their respective zones, the HCW’s own body and
professional apparel (“HCW Self”), and all the other areas and
surfaces outside the patient zone [
]. “Critical sites”
included clean sites such as medical devices or patient’s
body parts that have to be protected against microbial
colonization in order to avoid infections [
hygiene actions were registered as specific events and
coded as either “hand washing” or “hand disinfection”
with alcohol-based handrub. Patient zones were
established a-priori for each ICU setting to ensure accurate
and consistent coding (Fig. 2).
To assess the utility of the observation and coding
system, we performed a descriptive analysis of frequency
and duration of HSE. Coded event data were exported
as comma separate values (.cvs) files, merged and edited
in Excel (Microsoft, Redmond, WA) and analyzed in
STATA special edition 12.0 (StataCorp, College Station,
TX). Sequential analysis was additionally conducted to
identify HSE sequences of particular relevance to
infectious risks, as informed by the WHO ‘Five Moments for
Hand Hygiene’ [
]. We defined sequences of touching a
surface outside the patient zone followed by touching
any surface inside a patient zone as a ‘colonization event’
and a sequence of touching any surface, except a critical
site, followed by touching a critical site as an ‘infection
event’ (Table 1). A colonization event would correspond
to a modified WHO “Five Moments” concept’s Moment
1 “Before touching a patient” but include touching any
surface inside the patient zone and not only the patient.
This modification of Moment 1 was made to capture
more precisely colonization risk of the patient by
hospital flora that is brought into the immediate vicinity of
the patient and from there to the patient. An infection
event would correspond to WHO “Five Moments”
concept’s Moment 2 “Before clean/aseptic procedure”.
According to Sax et al., “Critical sites for infectious risks”
included breaks in the patient’s intact skin such as
wounds and catheter insertion sites, any patient mucous
membrane, invasive devices in-situ if the lumen was
accessed such as vascular or urinary catheters, and
semicritical or critical medical devices ready to be used on
the patient [
The 10 active care video sequences totaled 296.5 min and
featured eight nurses of whom seven were female and two
physicians of whom one was female, all right handed.
Overall, 4222 HSE occurred, translating in an overall
density of 14.2 HSE per minute or one HSE every 4.2 s.
Exemplarily, Fig. 3 demonstrates the coding timeline of all
Legend: HSE hand-to-surface exposure. The symbol ➔ denotes the direct sequence of two HSE. aWHO moment 1 with the modification that touching a surface
inside the patient zone with or without touching the patient counts as Patient Colonization Event
HSE and hand hygiene actions in the first 3 min of video
#7. Details on the frequency and nature of HSE and hand
hygiene actions overall and per each video sequence
appear in Table 2.
The mean and median duration of the 97 observed
hand hygiene actions were 12.9 (SD, 8.7) and 11 (range,
2–48) seconds, respectively. Patient colonization events
occurred overall 291 times, 139 for the left and 152 for
the right hand. Patient infection events were observed
overall 217 times, 103 for the left and 114 for the right
hand. Importantly, 117 (61%) of colonization events and
seven (2.3%) infection events occurred after HCWs
touching their own body. HCWs touched themselves
439 times (10% of all HSE), including their clothes 165
(38%), personal protective equipment 21 (5%), their face
24 (6%), and remaining bare skin or hair 229 (52%)
times; 13 (3%) times with gloved hands.
Hand hygiene occurred prior to 14 of the 191
colonization events and three of the 217 infection events,
resulting in a hand hygiene ‘adherence’ of 5% and 1%,
This unique video observation and coding approach,
that considers each single HSE by both HCW hands,
revealed a surprising reality of transmission
opportunities during real-world intensive care. The overall density
of 14.2 HSE per minute with which HCWs’ hands
touched surfaces during active patient care is high,
suggesting that hands acquire and deposit – and thus likely
transmit – potentially harmful microorganisms every 4 s
onto patients and surfaces in the care environment. We
identified sequences of particular interest for infection
prevention, such as patient zone entries and transitions
to critical sites, which each occurred roughly every 2
min of active patient care in an ICU. Hand hygiene was
performed on average 19.6 times per hour, which equals
one hand hygiene action every 3 min. It is not surprising
that participants only sustained hand rubbing for a
median of 11 s against the recommended 20–30 s
]. In fact, if meeting the recommended duration
for hand rubbing, almost one fifth of active patient
care time would have been spent on this activity.
Recent data indicating that 15 s might suffice are
comforting in this respect [
The approach used in this study is in line with a
human factors task analysis, whose underlying principle is
to break down a task to study its individual elements
]. In doing so, we aim to understand the factors that
influence the way work is being done and, ultimately,
Fig. 3 Timeline chart of video #7. Legend: An excerpt of the coding timeline from video #7. X-axis: time from 0:00–3:25 minutes. Y-Axis from top to
bottom: Hand hygiene action, hand-to-surface exposure (HSE) patient zone bare right hand inside, HSE to critical site with bare right hand, HSE outside
patient zone with bare right hand, HSE inside patient zone with bare left hand, HSE at critical site bare left hand, HSE outside patient zone with bare
left hand, HSE inside patient zone with gloved right hand, HSE to critical site with gloved right hand, HSE outside patient zone with gloved right hand,
HSE inside patient zone with gloved left hand, HSE at critical site with gloved left hand, HSE outside patient zone with gloved left hand
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what can be done to improve it [
]. In doing so, the
moments we report here are more frequent than those
usually reported in direct hand hygiene observation
studies. For example, tasks such as a dressing change are
typically seen as constituting one single hand hygiene
opportunity with an indication ‘Before clean/aseptic
procedure’ before the task and ‘After body fluid exposure
risk’ at the end of the task . In the current approach,
each care task is split into multiple HSEs, taking into
account both mobile objects [
] and the HCWs own
body, each scrutinized for potential hand contamination
and transmission. Furthermore, traditional hand hygiene
models are based on the assumption that surfaces within
the patient zone are colonized primarily with the
patient’s own flora. Our results [
], however, demonstrate
that frequent transitions of hands into the patient zone
without hand hygiene may lead to contamination of the
patient zone with foreign microorganisms. Such lapses
lead to an unsafe system state, which creates ambiguity
] and may result in unintentional patient harm.
Our approach revealed further noteworthy realities.
We considered the HCW’s own body as an ‘Outside
patient zone’ surface. More than half of all HSE sequences
(61%) from the “outside” to the “inside” patient zone
were due to ‘self-contact’. Current hand hygiene
guidelines often fail to address HCW self-contact as an
indication for hand hygiene [
]. Hence, such HSE are
usually ignored by observers. Second, much variation
exists in whether HCWs perceive their professional apparel
as a potential source of bacteria, leading to variations in
hand hygiene [
]. Additionally, as described by Sax &
Clack, relying on automatic, unconscious behaviors
fuelled by “mental models” for routine tasks is inherent
to the nature of human beings, allowing mental
resources to be spared for more complex tasks [
suggests that people often are unaware of what exactly
their hands do while they are focused on the main task
]. The average of 1.48 exposures per minute to a
HCW’s own body is consistent with previous findings
]. However, with only 4.87 exposures per hour to
“HCW Face”, our results differed from studies who
found that face contact occurred up to 15–23 times per
hour among students during 2-h lectures  or during
office-type work [
]. Finally, glove use was frequent,
representing one fifth of all HSE. Gloves represent
mobile surfaces that transport microorganisms like bare
hands. Further research could explore the nature of HSE
during glove use to inform best practice for glove
The “first-person view” of a head-mounted action
camera provides the advantage of an unobstructed view
of both hands and the surfaces they touch following the
healthcare worker [
] even when leaving the immediate
care area, neither of which can be guaranteed with a
fixed-position camera. From anecdotal reports by the
participants, their awareness of wearing a camera and
their activity being registered waned quickly, suggesting
a minor Hawthorne effect, yet this remains to be studied
systematically. Contrary to concerns about video
recording in acute care settings, we found that once healthcare
workers, patients, and their relatives were informed of
the study goals, objections to filming were rare. Video
observation of hand hygiene behavior has been used
] but never from a first-person view and
never to record HSEs.
Our approach has limitations. The analysis is limited to
a small sample of healthcare workers in three ICUs and in
consequence not representative for care in general. We do
not expect, however, the main findings of frequent HSE to
be categorically different. Furthermore, while the
sequential analysis we report here considers only pairs of two
consecutive HSE leading up to “colonization” or
“infection” events, it is important to recognize that HSE occur
in long sequential chains. The exact benefit of hand
hygiene at any of these moments has not been considered in
our current calculation, nor in the WHO ‘Five moments’
concept. In this line of thought, our approach might serve
as basis for more advanced future transmission risk
modelling. Our definition of a colonization event deviated from
‘Moment 1’ of the WHO hand hygiene concept by
including any object within the patient zone, not only the
patient. We did this intentionally to identify the
transmission trajectories most likely leading to contamination of
high-touch surfaces near the patient and ultimately, the
patient. On a technical note, the specific software is
expensive and its use requires expertise. Video coding is
more time-consuming than live observation. Hence,
before introducing this instrument into day-to-day practice
beyond research, simplification and automation is a
desirable next development step. Finally, the videos were coded
by a single coder (MS) and supervised by a second person
(LC) due to feasibility. The possibility to pause and rewind
the video likely minimized the risk of miscoding.
In conclusion, our approach produced a valid video
and coding instrument for analysis of detailed HSE
trajectories. Using a head-mounted action camera and a
comprehensive coding system, we could show for the
first time in a fast-paced, real clinical setting how
frequently healthcare workers’ hands touch surfaces,
corroborating the fast spread of microorganisms in
healthcare settings. Further development and use of this
method may contribute to the design of more efficient
Using a new head-mounted action camera and a
systematic coding tool, we could show for the first time how
healthcare workers’ hands touch surfaces in a real-world
clinical setting. This human factors approach to task
analysis demonstrated the hand trajectories via which
microorganisms can spread in healthcare and revealed
that hand hygiene adherence is lower than usually
reported by traditional on-site observations. This new
instrument may assist in designing more efficient
preventive strategies on an individual and systems level.
We would like to warmly thank the healthcare workers and patients who
had the courage and kindness to contribute to this research.
This research was partially funded by the Swiss Science Foundation grant
Availability of data and materials
The datasets used and/or analysed during the current study are available
from the corresponding author on reasonable request.
All authors contributed to the design, conduct of the study, the analysis of
the data, and the writing of the manuscript. All authors read and approved
the final manuscript.
Ethics approval and consent to participate
Due to the quality improvement scope of this study, the Ethics Review Board of
the Canton of Zurich formally waived the need for ethics review. Signed consent
was sought of patients or their relatives in accordance with the University Hospital
Zurich regulations for videotaping and photography. Participants gave their oral
consent after an in-depth explanation of the study goals and proceedings and
could opt out at any time. Data were rendered anonymous in the coding
Consent for publication
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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