Immune response against SARS-CoV-2 of primary healthcare personnel in a commune of Santiago, Chile: follow-up at 6 months.

BackgroundThe COVID-19 pandemic that emerged in Wuhan, China at the end of 2019, spread rapidly around the world with almost 600 million cases and 6.3 million deaths today. The most affected were health workers with at least three times the risk of contracting the disease than the general community. Most studies on seroprevalence in health workers focus on hospital care establishments and what happens in Primary Health Care (PHC) has not been investigated with the same intensity. Objectivesto determine the prevalence and know the variation of antibody titers for SARS-CoV-2 in serial samples of primary healthcare personnel from the commune of La Pintana. Methodan analytical observational study with a cross-sectional and a longitudinal component, carried out from November 2020 to June 2021. The first component consisted of an IgG antibody seroprevalence study performed at baseline (time 0) in volunteer of a universe of 900 workers. The longitudinal component considered the monitoring of IgG antibodies in those who presented a positive result at baseline and the analysis of neutralizing antibodies in a random sub-sample of 50% of them. Additionally, sociodemographic and clinical information was collected via a questionnaire. Univariate, bivariate, and longitudinal analyses were performed to evaluate differences in antibodies. The study was approved by the Universidad del Desarrollos Scientific Ethics Committee. Results463 primary healthcare workers participated, mostly women and with a median of 38 years; doctors and nurses represented 9.5% each and 14.7% had a history of COVID-19. The seroprevalence at baseline was 22.3% and was associated with younger age, being a doctor and having been in close contact of a case. IgG titers increased with the vaccine, but decreased over time. At the 6-month follow-up, 76% had neutralizing antibodies. Those belonging to indigenous peoples had higher IgG levels and higher rates of neutralizing antibodies. ConclusionHealthcare workers were highly affected by COVID-19, and the medical profession and younger age were factors associated with increased risk. Antibodies decrease over time, highlighting the importance of follow-up studies, as well as the importance of vaccination boosters in healthcare workers, especially those in PHC. FinancingThis project was funded by the Universidad del Desarrollo, COVID19-UDD 2020-21 Funds.