Humoral and cellular immune response against SARS-CoV-2 variants following heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination

Abstract

Cerebral venous thrombosis was reported as a rare but serious adverse event in young and middle-aged vaccinees following immunization with AstraZeneca's ChAdOx1-nCov-19 vaccine. As a consequence, several European governments recommended using this vaccine only in individuals older than 60 years leaving millions of ChAd primed individuals with the decision to either receive a second shot of ChAd or a heterologous boost with mRNA-based vaccines. However, such combinations have not been tested so far. We used Hannover Medical School's COVID-19 Contact (CoCo) Study cohort of health care professionals (HCP) to monitor ChAd primed immune responses before and three weeks after booster with ChAd or BioNTech/Pfizer's BNT162b2. Whilst both vaccines boosted prime-induced immunity, BNT induced significantly higher frequencies of Spike-specific CD4 and CD8 T cells and, in particular, high titers of neutralizing antibodies against the B.1.1.7, B.1.351 and the P.1 variants of concern of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2).

Recognition of Variants of Concern by Antibodies and T Cells Induced by a SARS-CoV-2 Inactivated Vaccine

“…These results are in line with previous reports that have shown a high correlation between these two techniques ( 15 , 18 ). A recent study that used the sVNT and cVNT to evaluate neutralizing antibodies against SARS-CoV-2 variants of concern in heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination has shown high correlation between both assays ( 22 ).…”

Spike-antibody waning after second dose of BNT162b2 or ChAdOx1

“…In the context of recent advice in support of booster vaccinations from the UK's Joint Committee on Vaccination and Immunisation, 13 and given the potentially rapid S-antibody decline suggested by these data, heterologous regimens, which preliminary data suggest elicit stronger antibody and T-cell responses, 14,15 might provide more durable immunity and greater protection against emerging variants. However, the ultimate effect of different dose intervals and various heterologous combinations on clinical outcomes remain important unanswered questions.…”

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“…These results are in line with previous reports that have shown a high correlation between these two techniques (15,18). A recent study that used the sVNT and cVNT to evaluate neutralizing antibodies against SARS-CoV-2 of concern in heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination has shown high correlation between both assays (22).…”