SARS-CoV-2 infection in general practice in Ireland: a seroprevalence study.

Michael O’callaghan ,Bernie Lynch,Eimear Kelly,Aidan Culhane,Monica Casey,Jarlath Healy,Paraic Meaney,Norelee Kennedy,Conor Hanrahan,Pat Harrold,Emmet Kerin,Cathal Walsh,P Burke ,Nuala H O’connell ,Peter Hayes ,J P Galvin ,Colum P Dunne ,Pat O’dwyer ,Billy O’connell ,Elizabeth J Ryan ,John W Duncan ,Ger P Lane ,Liam Glynn

doi:10.3399/bjgpo.2021.0038

Abstract

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody testing in community settings may help us better understand the immune response to this virus and, therefore, help guide public health efforts.AimTo conduct a seroprevalence study of immunoglobulin G (IgG) antibodies in Irish GP clinics.Design & settingParticipants were 172 staff and 799 patients from 15 general practices in the Midwest region of Ireland.MethodThis seroprevalence study utilised two manufacturers’ point-of-care (POC) SARS-CoV-2 immunoglobulin M (IgM)—IgG combined antibody tests, which were offered to patients and staff in general practice from 15 June to 10 July 2020.ResultsIgG seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%. Previous symptoms suggestive of COVID-19 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence. IgG antibodies were detected in approximately 80% of participants who had a previous PCR-confirmed infection. Average length of time between participants’ positive PCR test and positive IgG antibody test was 83 days.ConclusionPatients and healthcare staff in general practice in Ireland had relatively high rates of IgG to SARS-CoV-2 compared with the national average between 15 June and 10 July 2020 (1.7%). Four-fifths of participants with a history of confirmed COVID-19 disease still had detectable antibodies an average of 12 weeks post-infection. While not proof of immunity, SARS-CoV-2 POC testing can be used to estimate IgG seroprevalence in general practice settings.

Highlights

A novel virus, SARS-CoV-2, first detected in Wuhan, China, in December 2019,1 caused a global pandemic and >3.7 million deaths worldwide by 8 June 2021.2 The rapid spread of SARS-CoV-2, asymptomatic infection, and the requirement to understand how vaccination will impact the pandemic have fuelled interest in large-scale screening.[3,4,5,6,7,8]The standard method for diagnosis of SARS-C oV-2 infection remains a nucleic acid real-time polymerase chain reaction (PCR) test
immunoglobulin G (IgG) seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%
Previous symptoms suggestive of COVID-19 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence

Summary

Introduction

The standard method for diagnosis of SARS-C oV-2 infection remains a nucleic acid real-time PCR test. These tests have low levels of false positives, they are limited by a relatively high rate of false-negative results owing to multiple influencing factors, including virus shedding rates and the technical difficulty of performing an effective nasopharyngeal swab.[9] While rapid, deployed, POC testing has been employed successfully in cohorting patients with viral illness, influenza,[10] POC antigen tests to detect active SARS-C oV-2 infection in real-w orld settings, while evolving, have yet to replace PCR testing.[11,12]. Severe acute respiratory syndrome coronavirus 2 (SARS-C oV-2) antibody testing in community settings may help us better understand the immune response to this virus and, help guide public health efforts

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