Interventions to reduce the risk of coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) infection among workers outside healthcare settings

What is the aim of this review?

Coronavirus (COVID‐19) is a respiratory infectious disease that has spread globally. People infected with SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) can develop critical illnesses and may die, particularly older people, and those with underlying medical problems. Different interventions that attempt to prevent or reduce workers' exposure to SARS-CoV-2 in the workplace have been implemented during the pandemic. This Cochrane Review evaluated the effects of these interventions on the COVID-19 infection-rate, absenteeism, COVID-19-related mortality, and adverse events. 

What was studied in this review?

We searched for studies that examined interventions according to the following four categories: 1) elimination (for example self-isolation strategies); 2) engineering controls (for example barriers to separate or distance co-workers, and workers from members of the public); 3) administrative controls (for example working from home); 4) personal protective equipment (for example use of face masks or other types of face covering). We included studies of any worker outside the healthcare setting. We searched for studies without language or time restrictions.

What are the main findings of this review?

We screened more than 13 thousand reports, and included one study, conducted in 162 secondary and post-secondary schools in England, from March to June 2021. The study enrolled more than 24 thousand workers. In the 86 schools in the control group (standard isolation), staff who were considered COVID-19 contacts through contact tracing were required to self-isolate at home for 10 days. In the 76 schools in the intervention group (test-based attendance), staff who were considered COVID-19 contacts through contact tracing were not required to isolate. Instead, they took a daily rapid test (lateral flow antigen test) for seven days. If the rapid test was negative, the staff member could go to work. If the rapid test was positive, the staff member would self-isolate. The researchers wanted to know if there was a difference in COVID-related absence between the two methods.

We are uncertain whether a strategy of test-based attendance changes COVID-19 infection rates (any infection; symptomatic infection) compared with routine isolation after contact with a person with COVID-19. COVID-related absence may be lower or similar in the test-based attendance group. However, we were uncertain about these findings, because the number of infections was very low among the participants. Mortality, adverse events, quality of life, and hospitalisation were not measured. Seventy-one per cent of the test-based attendance group followed the strategy; the researchers did not report on compliance for the standard isolation group.

We identified one ongoing study that also addressed the effects of screening in schools.

Another ongoing study is evaluating the effects of using a face shield to prevent COVID-19 transmission.

We did not find any studies that studied engineering or administrative controls.

How up‐to‐date is this review?

We searched for studies that were available up to 14 September 2021.

Authors' conclusions: 

We are uncertain whether a test-based attendance policy affects rates of PCR-postive SARS-CoV-2 infection (any infection; symptomatic infection) compared to standard 10-day self-isolation amongst school and college staff. Test-based attendance policy may result in little to no difference in absence rates compared to standard 10-day self-isolation.

As a large part of the population is exposed in the case of a pandemic, an apparently small relative effect that would not be worthwhile from the individual perspective may still affect many people, and thus, become an important absolute effect from the enterprise or societal perspective. 

The included study did not report on any other primary outcomes of our review, i.e. SARS-CoV-2-related mortality and adverse events. No completed studies were identified on any other interventions specified in this review, but two eligible studies are ongoing. More controlled studies are needed on testing and isolation strategies, and working from home, as these have important implications for work organisations. 

Read the full abstract...

Although many people infected with SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) experience no or mild symptoms, some individuals can develop severe illness and may die, particularly older people and those with underlying medical problems. Providing evidence-based interventions to prevent SARS-CoV-2 infection has become more urgent with the spread of more infectious SARS-CoV-2 variants of concern (VoC), and the potential psychological toll imposed by the coronavirus disease 2019 (COVID-19) pandemic.  

Controlling exposures to occupational hazards is the fundamental method of protecting workers. When it comes to the transmission of viruses, such as SARS-CoV-2, workplaces should first consider control measures that can potentially have the most significant impact. According to the hierarchy of controls, one should first consider elimination (and substitution), then engineering controls, administrative controls, and lastly, personal protective equipment (PPE).


To assess the benefits and harms of interventions in non-healthcare-related workplaces to reduce the risk of SARS-CoV-2 infection relative to other interventions, or no intervention.

Search strategy: 

We searched MEDLINE, Embase, Web of Science, Cochrane COVID-19 Study Register, the Canadian Centre for Occupational Health and Safety (CCOHS),, and the International Clinical Trials Registry Platform to 14 September 2021. We will conduct an update of this review in six months.

Selection criteria: 

We included randomised control trials (RCT) and planned to include non-randomised studies of interventions. We included adult workers, both those who come into close contact with clients or customers (e.g. public-facing employees, such as cashiers or taxi drivers), and those who do not, but who could be infected by co-workers. We excluded studies involving healthcare workers. We included any intervention to prevent or reduce workers' exposure to SARS-CoV-2 in the workplace, defining categories of intervention according to the hierarchy of hazard controls, i.e. elimination; engineering controls; administrative controls; personal protective equipment.

Data collection and analysis: 

We used standard Cochrane methods. Our primary outcomes were incidence rate of SARS-CoV-2 infection (or other respiratory viruses), SARS-CoV-2-related mortality, adverse events, and absenteeism from work. Our secondary outcomes were all-cause mortality, quality of life, hospitalisation, and uptake, acceptability, or adherence to strategies. We used the Cochrane RoB 2 tool to assess the risk of bias, and GRADE methods to assess the certainty of evidence for each outcome.

Main results: 

Elimination of exposure interventions

We included one study examining an intervention that focused on elimination of hazards. This study is an open-label, cluster-randomised, non-inferiority trial, conducted in England in 2021. The study compared standard 10-day self-isolation after contact with an infected person to a new strategy of daily rapid antigen testing and staying at work if the test is negative (test-based attendance). The trialists hypothesised that this would lead to a similar rate of infections, but lower COVID-related absence. Staff (N = 11,798) working at 76 schools were assigned to standard isolation, and staff (N = 12,229) at 86 schools to the test-based attendance strategy. 

The results between test-based attendance and standard 10-day self-isolation were inconclusive for the rate of symptomatic PCR-positive SARS-COV-2 infection rate ratio ((RR) 1.28, 95% confidence interval (CI) 0.74 to 2.21; 1 study, very low-certainty evidence)).

The results between test-based attendance and standard 10-day self-isolation were inconclusive for the rate of any PCR-positive SARS-COV-2 infection (RR 1.35, 95% CI 0.82 to 2.21; 1 study, very low-certainty evidence).

COVID-related absenteeism rates were 3704 absence days in 566,502 days-at-risk (6.5 per 1000 days at risk) in the control group and 2932 per 539,805 days-at-risk (5.4 per 1000 days at risk) in the intervention group (RR 0.83; 95% CI 0.55 to 1.25). The certainty of the evidence was downgraded to low, due to imprecision.

Uptake of the intervention was 71 % in the intervention group, but not reported for the control intervention. 

The trial did not measure other outcomes, SARS-CoV-2-related mortality, adverse events, all-cause mortality, quality of life, and hospitalisation.

We found one ongoing RCT about screening in schools, using elimination of hazard strategies.

Personal protective equipment

We found one ongoing non-randomised study on the effects of closed face shields to prevent COVID-19 transmission.

Other intervention categories

We did not find studies in the other intervention categories.