Persistence of immunity and impact of third dose of inactivated COVID-19 vaccine against emerging variants

Abstract

This is a comprehensive report on immunogenicity of COVAXIN® booster dose against ancestral and Variants of Concern (VOCs) up to 12 months. It is well known that neutralizing antibodies induced by COVID-19 vaccines wane within 6 months of vaccination leading to questions on the effectiveness of two-dose vaccination against breakthrough infections. Therefore, we assessed the persistence of immunogenicity up to 6 months after a two or three-dose with BBV152 and the safety of a booster dose in an ongoing phase 2, double-blind, randomized controlled trial (ClinicalTrials.gov: NCT04471519). We report persistence of humoral and cell mediated immunity up to 12 months of vaccination, despite decline in the magnitude of antibody titers. Administration of a third dose of BBV152 increased neutralization titers against both homologous (D614G) and heterologous strains (Alpha, Beta, Delta, Delta Plus and Omicron) with a slight increase in B cell memory responses. Thus, seronversion rate remain high in boosted recipients compared to non-booster, even after 6 months, post third dose against variants. No serious adverse events observed, except pain at the injection site, itching and redness. Hence, these results indicate that a booster dose of BBV152 is safe and necessary to ensure persistent immunity to minimize breakthrough infections of COVID-19, due to newly emerging variants.Trial registration: Registered with the Clinical Trials Registry (India) No. CTRI/2021/04/032942, dated 19/04/2021 and on Clinicaltrials.gov: NCT04471519.

The effectiveness of the first dose COVID-19 booster vs. full vaccination to prevent SARS-CoV-2 infection and severe COVID-19 clinical event: a meta-analysis and systematic review of longitudinal studies

“…The characteristics of the included studies are summarized in Table 1 . They were conducted one in each of the following countries: India ( 21 ), Singapore ( 20 ), Malaysia ( 16 ), Israel ( 13 ), UK ( 19 ), Qatar ( 12 ), Brazil ( 18 ), Abu Dhabi ( 17 ), Turkey ( 15 ), and China ( 14 ). The proportion of the female ranged from 7.1 to 78.5% and the median age ranged from 33 to 56 years.…”

Effects of Negative Attitudes towards Vaccination in General and Trust in Government on Uptake of a Booster Dose of COVID-19 Vaccine and the Moderating Role of Psychological Reactance: An Observational Prospective Cohort Study in Hong Kong

“…This study found that prevalence of a booster dose uptake was 50% as of the follow-up survey, which was similar to the figure (46.6%) among people aged 20 or above as of 13 April 2022 reported by the Hong Kong government [ 13 ]. It has been documented that receiving a booster dose contributes to preventing not only infection, but also negative consequences caused by COVID-19 [ 9 , 10 , 11 ]. Thus, promoting uptake of a booster dose in Hong Kong is still a necessity.…”

“…Considering the waning immunity and the uncertain efficacy of vaccines against newly rapid emerging variants, uptake of a booster dose is of great importance. It has been documented that uptake of a booster dose of COVID-19 vaccine not only ensures persistent immunity, but also contributes to fighting against newly emerging variants [ 9 ]. Real-world evidence showed that compared to close contacts who received two doses, those who received a booster dose were less likely to be infected [ 10 ].…”

The humoral and cellular immune response of a third dose adenoviral-based vectored vaccine after a single or 2 shots of inactivated COVID-19 vaccine in healthy adults

“…The recent study also demonstrated a similar result in the substantially reduced humoral B-cell levels measured using the CYTOF method in humans after a month of immunizing with the inactivated vaccine [26]. The specific SAR-CoV 2 antibody level was maintained for at least 6 months after vaccination with the inactivated vaccine [27]. The high antibody level after the vaccination highlights the memory immune response and signifies the importance of booster immunization.…”