Immunology research update from www.immunopaedia.org.za.
COVID-19 vaccines are provided to all individuals, regardless of previous SARS-CoV-2 infection. We have previously highlighted research findings that showed vaccination with BNT162b2 (Pfizer/BioNTech) significantly boosts pre-existing SARS-CoV-2 immunity induced by natural infection (Read more: Antibody response to vaccination post-COVID-19 infection). Is this boosting effect observed in individuals vaccinated with other COVID-19 vaccines?
Ad26.COV2.S vaccine, single-dose adenovirus 26 vectored vaccine expressing the SARS-CoV-2 Wuhan-1 stabilized spike (S) protein, is highly effective against the development of severe COVID-19 was the first vaccine to be rolled in South Africa. The single-dose regimen makes it one of the most ideal vaccines to facilitate rapid roll-out in Africa. In a recent Pre-print, Keeton et al., “examined the effect of prior infection with ancestral (D614G) or Beta variants on Ad26.COV2.S immunogenicity approximately 28 days post-vaccination.”
Researchers showed that Ad26.COV2.S vaccination boosted circulating S-protein specific antibodies (Abs), neutralizing Abs (nAbs) and antibody-dependent cellular cytotoxicity (ADCC) in individuals previously infected during the 1st and 2nd waves to levels much higher than naïve individuals. Surprisingly, despite the longer time interval between wave 1 infection and vaccination (7 months), compared to wave 2 (2 months) the overall magnitude of vaccine-induced boosting was similar. Interestingly, researchers observed no substantial vaccine-induced boosting of S-specific CD4 T cells responses in previous SARS-CoV-2 infected individuals.
In summary, “Ad26.COV2.S vaccination following prior infection, even >6 months previously, may result in substantially enhanced protection against COVID-19, of particular relevance in settings of high SARS-CoV-2 seroprevalence.” These results, also highlight the potential role of cellular immunity in maintaining long-lasting immunity against future variants as results suggest that T cell recognition is not largely affected by mutations present in variants of interest.Researchers showed that Ad26.COV2.S vaccination boosted circulating S-protein specific antibodies (Abs), neutralizing Abs (nAbs) and antibody-dependent cellular cytotoxicity (ADCC) in individuals previously infected during the 1st and 2nd waves to levels much higher than naïve individuals. Surprisingly, despite the longer time interval between wave 1 infection and vaccination (7 months), compared to wave 2 (2 months) the overall magnitude of vaccine-induced boosting was similar. Interestingly, researchers observed no substantial vaccine-induced boosting of S-specific CD4 T cells responses in previous SARS-CoV-2 infected individuals.
Journal Article: Keeton et al., 2021 (Pre-print). Prior infection with SARS-CoV-2 boosts and broadens Ad26.COV2.S immunogenicity in a variant dependent manner. MedRxiv