Study of SARS-CoV-2 antibodies in >5,000 healthcare workers

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the causative agent for coronavirus disease 2019 (COVID-19) – has claimed nearly 50,000 lives in the United Kingdom alone. The UK is now seeing a steep rise in cases once again as it experiences a ‘second wave’ of infections nationwide, with over 1.2 million confirmed COVID-19 cases overall. Controlling the transmission of the virus is vital to stem the tide of the pandemic.

While the common risk factors among the general population are well-described, the uncertainty and exposure of healthcare workers, who are at a higher risk of SARS-CoV-2 infection, are not explicitly known. Given the vital role that hospitals and their staff play in battling the virus and saving lives, understanding the risk factors at play for healthcare professionals and support staff will be crucial if the UK is to get on top of the pandemic.

The Study

To address this, Daniel J Cooper and his team of researchers conducted a prospective seroepidemiological study to systematically evaluate specific risk factors for healthcare workers. They used a SARS-CoV-2 immunoassay and analyzed the risk factors for seropositivity using multivariate logistic regression. This study enumerates the specific risk factors among healthcare workers. Their findings are available on the medRxiv* preprint server.

The prospective cohort in this study includes almost 6,000 healthcare workers at a large teaching hospital in the East of England. Of the 5,698 staff-tested, 410 turned positive (7·2% seroprevalence) for SARS-CoV-2 antibodies. The seroprevalence was higher in the healthcare workers who were working in designated COVID-19 areas.

It was found that the healthcare assistants and domestic and portering staff had significantly higher seroprevalence than other staff groups. For the first time, this study shows that healthcare assistants represent a key at-risk occupational group. This challenges previous findings that indicate significantly higher risk among nursing staff.

“Wider asymptomatic testing in healthcare facilities has the potential to reduce the spread of SARS-CoV-2 within hospitals, thereby reducing patient and staff risk and limiting spread between hospitals and into the wider community,” say the researchers.

This study was done after adjusting for age, sex, ethnicity and COVID-19 working location. Among the staff, the Black, Asian and minority ethnicities (BAME) individuals had a high risk of infection compared to the white staff, independent of their working area. The authors demonstrate that occupational factors alone do not account for all of the increased risks among this group. As occupational risks do not explain the increased and significant risk of COVID-19 amongst BAME staff, further evaluation is required to identify the cause.

Even though the seroprevalence among healthcare workers who do not work in areas with confirmed COVID-19 patients was only marginally higher than the general population, it suggests that an increased risk amongst healthcare workers arises through occupational exposure to confirmed cases.

The symptoms associated with seropositivity were loss of sense of taste or smell, fever and myalgia (pain in muscles). However, it is important to note that 31% of staff who tested positive reported no prior symptoms consistent with COVID-19. This emphasizes the contribution of infection transmission by an asymptomatically infected population.

To mitigate and reduce the risk of occupational SARS-CoV-2 infection, the factors aiding the risks need to be methodically identified. This study reports healthcare worker specific risk factors based entirely on seroprevalence data, identifying two main factors: increased risk when caring for confirmed COVID-19 cases and among those identifying as being within specific ethnic groups (BAME staff).

It is important to understand how population-level risk factors influence occupational risk in defined demographic groups.

Summing Up

The authors conclude that the risk of SARS-CoV-2 infection amongst healthcare workers is heterogeneous and influenced by COVID-19 working location, role, age and ethnicity. And increased risk amongst BAME staff cannot be accounted for solely by occupational factors.

This study prioritizes efforts to reduce the risk of SARS-CoV-2 infection among healthcare workers; the meticulous focus is imperative. Hand hygiene, better access to high quality personal protective equipment (PPE), and frequent asymptomatic testing must be well-placed mechanisms for healthcare workers, the researchers argue.

As the UK is presently witnessing another surge in COVID-19 diagnoses, protecting healthcare workers by identifying risk factors for SARS-CoV-2 infection is paramount - this study is aligned towards this goal.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Dr. Ramya Dwivedi

Written by

Dr. Ramya Dwivedi

Ramya has a Ph.D. in Biotechnology from the National Chemical Laboratories (CSIR-NCL), in Pune. Her work consisted of functionalizing nanoparticles with different molecules of biological interest, studying the reaction system and establishing useful applications.


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