Neutralizing responses in fully vaccinated with BNT162b2, CoronaVac, ChAdOx1, and Ad26.COV2.S against SARS-CoV-2 lineages in Colombia, 2020-2021

BackgroundBy March 2022, around 34 million people in Colombia had received a complete scheme of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) including, mRNA-based vaccines, viral vectored coronavirus vaccines, or the inactivated whole virus vaccine. However, as several SARS-CoV-2 variants of concern (VOC) and interest (VOI) co-circulate in the country, determining the resistance level to vaccine-elicited neutralizing antibodies (nAbs) is useful to improve the efficacy of COVID-19 vaccination programs. MethodsMicroneutralization assays with the most prevalent SARS-CoV-2 lineages in Colombia during 2020-2021 were performed using serum samples from immunologically naive individuals between 9 and 13 weeks after receiving complete regimens of CoronaVac, BNT162b2, ChAdOx1, or Ad26.COV2.S. The mean neutralization titer (MN50) was calculated by the Reed-Muench method and used to determine differences in vaccine-elicited nAbs against the SARS-CoV-2 lineages B.1.111, P.1 (Gamma), B.1.621 (Mu), and AY.25.1 (Delta). ResultsThe most administered vaccines in the country, BNT162b2 and CoronaVac, elicited significantly different nAb responses against Mu, as the GMTs were 75.7 and 5.9-fold lower relative to the control lineage (B.1.111), while for Delta were 15.8 and 1.1-fold lower, respectively. In contrast, nAb responses against Mu and Delta were comparable between ChAd0x1-s and Ad26.COV2.S as the GMTs remained around 5 to 7-fold lower relative to B.1.111. ConclusionsThe emergence of SARS-CoV-2 variants in Colombia with a significant capacity to escape from vaccine-elicited nAbs indicates that a booster dose is highly recommended. Furthermore, other non-pharmacological measures should be retained in the vaccinated population.