Effects of boosted mRNA and adenoviral‐vectored vaccines on immune responses to omicron BA.1 and BA.2 following the heterologous CoronaVac/AZD1222 vaccination

Abstract

The coronavirus 2019 omicron variant has surged rapidly and raises concerns about immune evasion even in individuals with complete vaccination, because it harbors mutations. Here we examine the capability of booster vaccination following CoronaVac/AZD1222 prime to induce neutralizing antibodies (NAbs) against omicron (BA.1 and BA.2) and T‐cell responses. A total of 167 participants primed with heterologous CoronaVac/AZD1222 for 4–5 months were enrolled, to receive AZD1222, BNT162b2, or mRNA‐1273 as a third dose. Reactogenicity was recorded. Immunogenicity analyses of severe acute respiratory syndrome coronavirus 2‐binding antibodies were measured using enzyme‐linked immunosorbent assay. The NAb titers against omicron BA.1 and BA.2 were determined using the focus reduction neutralization test (FRNT50) and total interferon‐γ responses were measured to observe the T‐cell activation. A substantial loss in neutralizing potency to omicron variant was found at 4–5 months after receiving the heterologous CoronaVac/AZD1222. Following booster vaccination, a significant increase in binding antibodies and neutralizing activities toward delta and omicron variants was observed. Neutralization to omicron BA.1 and BA.2 were comparable, showing the highest titers after boosted mRNA‐1273 followed by BNT162b2 and AZD1222. In addition, individuals boosted with messenger RNA (mRNA) vaccines develop a T‐cell response to spike protein, whereas those boosted with AZD1222 did not. Reactogenicity was mild to moderate without serious adverse events. Our findings demonstrated that mRNA booster vaccination is able to overcome waning immunity to provide antibodies that neutralize omicron BA.1 and BA.2, as well as a T‐cell response.

RNA Interference Approach Is a Good Strategy against SARS-CoV-2

“…The high mutation frequency of SARS-CoV-2 poses a serious challenge to antiviral agents or antagonist peptide development. Compared with classical vaccines, mRNA vaccines have the advantage of rapid preparation in response to viral antigenic mutations, but their effectiveness is still limited [ 20 ]. In the mRNA vaccine’s design, the SP has been used as the antigen for vaccine development.…”

Immunogenicity after a Third COVID-19 mRNA Booster in Solid Cancer Patients Who Previously Received the Primary Heterologous CoronaVac/ChAdOx1 Vaccine

“…Data from healthy individuals came from a previously published study [ 19 ]. One hundred and seven healthy individuals who previously received the CoronaVac followed by the ChAdOx1 vaccine were administered either BNT162b2 or mRNA-1273 vaccines.…”

“…Due to the emergence of the SARS-CoV-2 Omicron variant of concerns and the waning of vaccine-induced immune response, third dose vaccination with mRNA vaccine is now recommended [ 14 , 15 , 16 , 17 , 18 ]. In healthy adults, a third booster with mRNA COVID-19 vaccine following the heterologous CoronaVac/ChAdOx1 regimens demonstrated good vaccine efficacy against variants of concern [ 19 ]. No data regarding the efficacy of a third mRNA COVID-19 vaccine booster are available for solid cancer patients primed with this heterologous regimen.…”

Adenoviral Vector-Based Vaccine Platform for COVID-19: Current Status

“…The greatest titers for omicron BA.1 and BA.2 neutralization were obtained following mRNA-1273-boosted dose, then BNT162b2 and AZD1222. In contrast to those who received AZD1222 as a booster, those who received messenger RNA (mRNA) vaccinations acquire a T-cell response to the spike protein [ 139 ].…”