Introduction

The COVID-19 pandemic has resulted in major disruptions to business activity and changed the way people work; many governments and employers have mandated working-from-home (WFH) wherever possible. In the UK, a limited number of essential key workers have continued to attend their usual workplace throughout the pandemic (e.g. healthcare workers, carers, manufacturing, pharmaceuticals sites, etc.). The UK government had initially published a COVID-19 recovery strategy aiming for “significant normality” by Christmas; however the resurgent of the virus and likelihood of a third wave means the government had to prepare for different scenarios. The aim is now to return towards normality in Spring 2021. It is likely that COVID-19 will continue into 2021 until majority of the population are vaccinated [1]. Temperature checks face mask and social distancing rules are likely to remain when employees return to the office. However, considerable uncertainly still remains with regards to the impact on the infection rate when business activity returns to normality.

Testing for acute SARS-CoV-2 infection is undertaken through nasal and throat swabs with rt-PCR for the detection of this novel virus. However, another approach for the detection of acute and previousinfection relies on the detection of IgG or IgM antibodies in blood either assessed through laboratory ELISA techniques or using lateral flow serology kits. The latter is a relatively expedient and inexpensive way of assessing for the presence of antibodies, though widespread adoption has been hampered by availability and concerns relating to sensitivity or specificity [2,3].

There have been a number of studies that have assessed acute infection rates at certain time points. However,there are relatively few studies assessing the prevalence or previous exposure of COVID-19 infection across a variety of local populations. A UK government sponsored study shows that the overall population weighted prevalence among blood donors in England was 6.7% (unadjusted; 95% CI 6.1%-7.3%) or 7.1% (after adjustment for the accuracy of the Euroimmun assay; 95% CrI 6.5%-7.8%) for the period 8th June - 6th July 2020 (weeks 24-28) [4]. We know little about the prevalence of COVID-19 within organisations, and the impact on the infection rate when employees return to work. Accord Healthcare has undertaken a study to estimate the prevalence of prior SARS-CoV-2 exposure amongst its employees and compare it to national and regional statistics, as well as to monitor the impact on the infection rate when the working from home restriction is relaxed. Accord Healthcare has employees across different geographical locations in the EU, with individuals travelling to the pharmaceutical factories to continue medicine production (essential workers) during the pandemic as well as others working from home. This manuscript reports the initial results from the UK and Ireland employee population.

Research Methodology

All eligible (permanent employees of Accord Healthcare and subsidiary companies, Astron, and Lambda) in the UK and Ireland working across a variety of departments and locations(e.g. office, factory, field, or home based) were invited to have an antibody test using lateral flow serology for SARS-CoV-2 throughout June and July 2020. The decision to participate was entirely voluntary. Eligible participants were asked to complete a questionnaire regarding normal place of work, place of work during the pandemic, any previous COVID-19 related symptoms, previous tests, etc. Employees with haemophilia or currently taking anticoagulants were asked to seek medical approval before their participation.

The primary endpoint is the proportion of positive and negative cases, presented as negative (no exposure), recent exposure (IgM positive and IgG positive), or previous exposure (IgM negative and IgG positive). Recent positive cases will also undergo an antigen test to determine if they are viral shedding. Secondary endpoints include comparisons against national statistics, comparison against regional statistics, sub-group analysis (age, gender, ethnicity), impact of a relaxed lock-down on the infection rate, and proportion of positive antigen tests. Exploratory endpoints include duration of antibody presence in the body to provide additional data with regards to possible re-infection (data being assembled and results to be provided in a later edition).

All data were blinded by the assessors and remained anonymous. Tests were conducted by Occupational Health practitioners. This study was approved by an Accord Ethics Committee.

Lateral Flow Serology testing

We elected to use the Healgen Lateral Flow COVID-19 serology testing cartridges. The illustration of the test kit isshown in Figure 1 and management of positive/negative results explained in Figure 2. The Healgen lateral flow serology assay has been tested previously using convalescent sera in individuals confirmed to have had COVID-19 infection from rt-PCR swabs and also with pre-pandemic sera as negative infections. The study revealed a 100% sensitivity provided the test is undertaken 14 days or more after symptoms and a 96% specificity [5,6]. These data support the use of this kit for rapid assessment of subjects’ antibody status in the community.

A positive result for IgG suggests an infection likely took place at least 10 days prior to the test being taken in the absence of symptoms, reflects spent prior infection [6,7]. IgM antibodies are generated as the first antibody response to infection and rise from about the fifth day post-contamination and persist only for a short period of time months [6,8].

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