Regarding long-term immunity and prevention of coronavirus variant infection, the 2nd dose of mRNA vaccination might be highly advantageous when compared to a single dose of coronavirus vaccination or homologous 2nd challenge ChAdOx1 nCoV-19 (ChAdOx1).

This study was carried out to compare antibody responses following 1st and 2nd doses of ChAdOx1 and BNT162b2 vaccines with those in convalescent people recovering from severe or mild coronavirus disease.

Collection of blood samples from adults having mild and severe coronavirus disease and medical care workers who were given ChAdOx1 nCoV-19 vaccine (2nd dose at twelve-week intervals) and BNT162b2 vaccine (2nd dose at three-week intervals) was done. Utilizing an in-house-developed enzyme-linked immunosorbent assay, a comparison was done via immunoglobulin G immune responses to SARS-CoV-2 specific spike protein.

Overall, 53 participants (41 having severe coronavirus disease, and 12 having mild coronavirus disease), respectively, were examined. Furthermore, 73 medical care workers, including 37 who were given ChAdOx1 nCoV-19 and 36 who were given BNT162b2, were recruited.

The antibody responses following 1st and 2nd doses of ChAdOx1 nCoV-19 vaccine or 1st dose of BNT162b2 vaccine were comparable to those in convalescent people having mild coronavirus disease, but reduced than those in convalescent people having severe COVID-19, respectively. But, following 2nd dose of BNT162b2 vaccine, antibody response was noted to be similar to that in convalescent people suffering from severe coronavirus disease.

Hence, the 2nd dose of mRNA vaccination provides benefits like long-term immunity and better prevention of coronavirus variant infection.