LAUSR

Background: Reports on the evaluation of immune responses to different COVID 19 vaccines are limited. Similarly, effects of age and gender have not been well explored as variables that could impact on the vaccine-induced antibody response. Therefore, seroprevalence of anti SARS CoV 2 specific antibodies in vaccinated and vaccine naive adult Nigerians was determined in this study. Methodology: A total of 141 adults were enrolled into this study. Presence or absence of SARS CoV 2 infection was confirmed by real time reverse transcriptase polymerase chain reaction (RT PCR) assay on nasopharyngeal and oropharyngeal swab specimens. Anti SARS CoV 2 Specific IgG and IgM antibodies were qualitatively detected using a Rapid Diagnostic Test kit. Results: Pre vaccination, 77% of the study participants had never had PCR confirmed COVID-19 test yet 66.7% of them were seropositive for SARS CoV 2 antibodies. Of 111 COVID-19 vaccinated participants, 69.2% and 73.8% of them had SARS-CoV-2 specific IgG post-first and second doses of COVID 19 vaccine respectively. However, 23.1% and 21.4% of the participants who have had first and second doses respectively had no detectable anti-SARS-CoV-2 antibodies. The proportion of participants with SARS-CoV-2 specific IgG was insignificantly higher in those between the ages of 18 to 40 years and 41 to 59 years compared with individuals aged 60 years and above. No significant association was observed between gender and seropositivity for SARS CoV 2 antibodies. Conclusion: There is high SARS CoV 2 antibody seroprevalence among Nigerian adults who never had PCR-confirmed COVID 19. Also, there is the need for anti-SARS-CoV-2 antibodies screening post vaccination as this could be essential in achieving herd immunity. Age and gender do not seem to have significant association with seropositivity.