This is the 10th update alert for a living rapid review on the epidemiology of and
risk factors for coronavirus infection in health care workers (HCWs) (1). Initial
updates were monthly through update alert 7 (2, 3), then bimonthly for update alerts
8 (4) and 9 (5), which focused on risk factors for coronavirus infection. Beginning
with this update, we limited inclusion to studies that reported adjusted risk estimates
to focus on higher-quality evidence, and the update interval was extended to biannually
given stable findings in prior updates. We excluded non–peer-reviewed studies, except
for those comparing mask types and done in or after January 2021, which is when the
Delta variant emerged. Searches for this update were done from 25 April to 24 October
2021 using the same search strategies as the original review, and 8656 citations were
identified. We applied the same inclusion criteria used for prior updates, other than
described above. Twenty studies on risk factors for SARS-CoV-2 infection were added
for this update (Supplement Tables 1 to 6) (6–25).
The original rapid review included 34 studies on risk factors for coronavirus infections
(3 studies on SARS-CoV-2 infection, 29 studies on SARS-CoV-1 infection, and 2 studies
on Middle East respiratory syndrome–CoV infection) (1); 93 studies (91 studies on
SARS-CoV-2 infection and 2 studies on Middle East respiratory syndrome–CoV infection)
were added in prior updates (2–5, 26–29). For this update, 4 cohort studies (6–9)
(including 1 preprint study [9]), 15 cross-sectional studies (10–24), and 1 case–control
study (25), all on SARS-CoV-2, were added (Supplement Table 1). Ten studies were done
in Europe, and 7 were done in North America. The others were done in Kuwait, Qatar,
and Turkey. In 18 studies, data were collected from February to December 2020. One
non–peer-reviewed study collected data from June 2020 to March 2021 (9), and 1 other
study collected data from December 2020 to May 2021 (25). As in prior updates, new
studies had methodological limitations, including potential recall bias, limited control
of confounders, and low or unclear participation rates.
New evidence was consistent with prior updates in finding no consistent association
between risk for SARS-CoV-2 infection in HCWs and age (13 studies [6, 8, 10, 11, 14–17,
19, 22–25]), sex (13 studies [6, 8, 10, 11, 13, 14, 16, 17, 19, 22–25]), or HCW role
(15 studies [6, 7, 11–16, 19–25]) (Supplement Table 2). Also consistent with prior
updates, 5 studies done in the United States, Canada, or Ireland found that non-White
race (Black, Asian or Asian/Pacific Islander, or combined non-White races) or Hispanic
ethnicity was associated with increased risk for infection (Supplement Table 2) (6,
8, 11, 15, 16).
Thirteen new studies reported on the association between exposures and likelihood
of infection (Supplement Table 3) (6–8, 11, 12, 14, 16, 17, 19, 20, 23–25). Seven
studies (7, 8, 12, 19, 20, 23, 24) consistently found that exposure to COVID-19 in
a household or private setting was associated with increased risk for SARS-CoV-2 infection
in HCWs (adjusted odds ratios [ORs] ranged from 2.55 to 8.98) (Supplement Table 3).
In most studies, household or private setting exposure was a stronger risk factor
than work exposure. Nine studies found that direct contact in a work environment to
patients with COVID-19 was associated with increased risk for infection (7, 8, 11,
12, 17, 19, 23–25).
No new study evaluated the association between education or training (Supplement Table
4) and risk for infection in HCWs. One non–peer-reviewed study (9) based on data collected
from June 2020 to March 2021 (mostly before the emergence of the Delta variant) found
that primarily using filtering facepiece 2 masks versus surgical masks was associated
with decreased risk for SARS-CoV-2 infection (adjusted OR for seroconversion, 0.73
[95% CI, 0.53 to 1.00]) (Supplement Table 5).
Two new studies (10, 18) examined other infection prevention and control measures
and risk for SARS-CoV-2 infection (Supplement Table 6). One study found that glove
use compared with nonuse (adjusted OR, 2.93 [CI, 1.19 to 7.22]) was associated with
an increased risk for infection; estimates for gown use (adjusted OR, 0.64 [CI, 0.31
to 1.32]) and goggle use (adjusted OR, 1.27 [CI, 0.72 to 2.27]) were imprecise (10).
The other study (18) found that being a frontline HCW and performing an aerosol-generating
procedure on a patient with COVID-19 without appropriate personal protective equipment
(including a mask, apron, gown, and/or gloves) was associated with increased risk
for infection versus not being a frontline worker (adjusted OR, 2.39 [CI, 1.00 to
6.18]). Both studies were limited with regard to controlling for exposures and other
confounders, including adherence to personal protective equipment use.
Evidence across all risk factors is summarized in Supplement Table 7. Despite large
numbers of studies and participants, most evidence remains low or moderate certainty
because of methodological limitations, imprecision, and inconsistency.
Supplementary Material
Click here for additional data file.