Elevated serum IgA after vaccination against SARS-CoV-2 in a cohort of high-risk first responders

This study recruited first responders and other personnel from police, firefighters, and emergency medical services (EMS) agencies.Details regarding recruitment and study participants have been previously published⁷Participants will be assessed at baseline regarding previous exposure to SARS-CoV-2, duration of isolation from the workplace, symptomatic illness that may be consistent with COVID-19, and confirmed diagnosis of COVID-19. and investigated at follow-up.

Based on serological and clinical evidence of SARS-CoV-2 infection and disease, individuals were classified as: clear COVID-19 Includes participants with a positive COVID-19 RT-PCR test or antigen test or positive IgG antibodies combined with a history of contact with a COVID-19-infected person and symptoms compatible with COVID-19 . probably COVID-19 Includes participants who are positive for IgA or IgG antibodies and have a history of symptoms consistent with COVID-19 or a history of contact with a person infected with COVID-19 and a history of symptoms consistent with COVID-19. Possible COVID-19 Include participants with a history of symptoms consistent with COVID-19 who have been in contact with a person infected with COVID-19 and who do not have positive IgG or IgA antibodies. Definite asymptomatic infection Participants with positive IgA or IgG antibodies with a history of exposure to COVID-19 patients with no history of symptoms compatible with COVID-19, or positive IgG antibodies with no history of exposure and no history of COVID-19 patients Include participants with symptoms compatible with COVID-19; Possibility of asymptomatic infection Include IgA antibody-only participants with no history of contact with a person infected with COVID-19 and no history of symptoms relevant to COVID-19, No evidence of SARS-CoV-2 infection or COVID-19 Participants who were all antibody negative and who had no history of human contact with COVID-19 or symptoms consistent with COVID-19 will be included. Participants were classified based on their last pre-vaccination assessment.

Participants’ sera were assayed at ICON Laboratories at three time points (baseline, 2–3 months, and 6 months) using the Abbott Architect Anti-SARS-CoV2 Chemiluminescent Microparticle Immunoassay (MIA) for IgG were tested for capsid protein, anti-N). Euroimmun Anti-SARS-CoV-2 ELISA on IgG (spike anti-S1 domain, anti-S) and Euroimmun Anti-SARS-CoV2 ELISA on IgA (spike anti-S1 domain). Anti-N IgG results were classified as either positive or negative based on a signal/cutoff index of 1.4 or greater for a positive result. Association with anti-S IgG and IgA was assessed based on an optical density ratio of ≥1.1, corresponding to a positive test according to manufacturer’s specifications.

Immunization status was defined as complete if participants received a complete series at least 14 days prior to collection. Immunization was classified as partial vaccination if he had received only 1 of 2 doses 14 days prior to collection. All others were classified as unvaccinated. Individuals who completed the series at least 14 days before her second collection were assessed based on their responses at the second collection only.

To assess the impact of previous SARS-CoV-2 infection on vaccine response, definite COVID-19, probable COVID-19, probable COVID-19, or definite asymptomatic infection were compared with those classified as having no evidence of SARS. CoV-2 infection or COVID-19. Percentages of positive antibodies by type were summarized by vaccine type, vaccine status, and categorized history of infection or disease.

Data management and statistical analysis were performed using SAS® version 9.4 (SAS Institute Inc., Cary, NC, USA). A chi-square test was used to analyze differences in antibody positivity based on exposure and disease category, and previous receipt of vaccine. A median was calculated and a non-Wilcoxon rank sum test was performed to assess differences in his IgG and IgA ratios based on past history of COVID-19 and vaccine manufacturers. Data visualization was performed in R using the ggplot2 package.

IRB approval was obtained from Western IRB, protocol # 20201662. Informed consent was obtained from all participants at the time of study recruitment. All research recruitment and laboratory tests were conducted in accordance with relevant guidelines and regulations.