mRNA booster immunization elicits potent neutralizing serum activity against the SARS-CoV-2 Omicron variant

Abstract

The Omicron variant of SARS-CoV-2 is causing a rapid increase in infections across the globe. This new variant of concern carries an unusually high number of mutations in key epitopes of neutralizing antibodies on the viral spike glycoprotein, suggesting potential immune evasion. Here we assessed serum neutralizing capacity in longitudinal cohorts of vaccinated and convalescent individuals, as well as monoclonal antibody activity against Omicron using pseudovirus neutralization assays. We report a near-complete lack of neutralizing activity against Omicron in polyclonal sera from individuals vaccinated with two doses of the BNT162b2 COVID-19 vaccine and from convalescent individuals, as well as resistance to different monoclonal antibodies in clinical use. However, mRNA booster immunizations in vaccinated and convalescent individuals resulted in a significant increase of serum neutralizing activity against Omicron. This study demonstrates that booster immunizations can critically improve the humoral immune response against the Omicron variant.

Antibody response against SARS-CoV-2 Delta and Omicron variants after third-dose BNT162b2 vaccination in allo-HCT recipients

“…After booster immunization, 33 (87%), 31 (82%), and 23 (60.5%) patients had detectable NAb against the WT, Delta, and Omicron variants, respectively. As previously observed in healthy individuals ( Zeng et al., 2021 ; Gruell et al., 2022 ), patients had higher NT50 titers against the WT virus (median 1,078, geomean 566.8, p < 0.0001) than against the Delta (median 202, geomean 200.4) and the Omicron (median 80.5, geomean 74.4, p < 0.0001) variants following booster immunization. Furthermore, there were strong correlations between binding RBD Ab and NAb levels (p < 0.001; Figure S1 C).…”

Modelling SARS-CoV-2 Binding Antibody Waning 8 Months after BNT162b2 Vaccination

“…The waning of antibodies in Pr-CoV is consistent with a large study from Qatar, where the cumulative incidence of breakthrough infections was 5.5 times higher in vaccinated individuals with no prior COVID-19 infection compared with Pr-CoV ones [46]. Several studies suggest that the quality of immune response in vaccinated Pr-CoV improves over time in terms of neutralisation capacity and breadth (hybrid immunity), with the improved neutralisation of new variants including VOC Omicron, especially after the use of booster dose [47][48][49][50][51][52][53][54][55][56][57][58].…”

Risk of Vaccine Breakthrough SARS-CoV-2 Infection and Associated Factors in Healthcare Workers of Trieste Teaching Hospitals (North-Eastern Italy)

“…In particular, emerging new variants of SARS-CoV-2 worldwide were reportedly capable to infect fully vaccinated individuals, causing symptomatic COVID-19 among HCWs. Booster immunizations may improve the humoral immune response against the Omicron variant, accuontable for a rapid increase of SARS-CoV-2 infections worldwide [25]. In our study we analyzed the risk of breakthrough SARS-CoV-2 infection among HCWs before booster immunization.…”