BNT162b2 effectiveness against Delta & Omicron variants in teens by dosing interval and duration

Abstract

Background and Objectives Two- and three-dose BNT162b2 (Pfizer-BioNTech) mRNA vaccine effectiveness (VE) against SARS-CoV-2 infection, including Delta and Omicron variants, was assessed among adolescents in two Canadian provinces where first and second doses were spaced longer than the manufacturer-specified 3-week interval. Methods Test-negative design estimated VE against laboratory-confirmed SARS-CoV-2 infection among adolescents 12-17 years old in Quebec and British Columbia, Canada between September 5, 2021 (epi-week 36), and April 30, 2022 (epi-week 17). Delta-dominant and Omicron-dominant periods spanned epi-weeks 36-47 and 51-17, respectively. VE was assessed from 14 days and explored by interval between first and second doses, time since second dose, and with administration of a third dose. Results Median first-second dosing-interval was ~8 weeks and second-third dosing-interval was ~28-31 weeks. Median follow-up post-second-dose was ~10-11 weeks for Delta-dominant and ~21-22 weeks for Omicron-dominant periods, and ~3-9 weeks post-third dose. VE against Delta was ≥90% to at least the 5th month post-second dose. VE against Omicron declined from ~65-75% at 2-3 weeks to ≤50% by the 3rd month post-vaccination, restored to ~60-65% shortly following a third dose. VE exceeded 90% against Delta regardless of dosing-interval but appeared improved against Omicron with ≥8 weeks between first and second doses. Conclusion In adolescents, two BNT162b2 doses provided strong and sustained protection against Delta but reduced and rapidly-waning VE against Omicron. Longer interval between first and second doses and a third dose improved Omicron protection. Updated vaccine antigens, increased doses and/or dosing-intervals may be needed to improve adolescent VE against immunological-escape variants.

Immunogenicity, safety and clinical outcomes of the SARS-CoV-2 BNT162b2 vaccine in adolescents with type 1 diabetes

“…The inconsistency in methodology, especially the definition of COVID-19 vaccine breakthrough infections among different studies limits the comparison of findings. Nonetheless, several studies demonstrated that the two-dose BNT162b2 vaccine provides strong protection against SARS-CoV-2 delta variant in adolescents (40,45,46). However, as more transmissible novel strain, omicron variant became prevalent worldwide since the start of 2022, the vaccine effectiveness was found to be decreased remarkably (46)(47)(48).…”

“…Nonetheless, several studies demonstrated that the two-dose BNT162b2 vaccine provides strong protection against SARS-CoV-2 delta variant in adolescents (40,45,46). However, as more transmissible novel strain, omicron variant became prevalent worldwide since the start of 2022, the vaccine effectiveness was found to be decreased remarkably (46)(47)(48). In this research, the 6-month postvaccination follow-up period through which the cases with breakthrough infections were diagnosed coincided with the time span when the omicron variant displaced the previously dominant delta variant in Turkey (49,50).…”

Temperature Influences the Interaction between SARS-CoV-2 Spike from Omicron Subvariants and Human ACE2

“…Since the start of the pandemic, strategies such as vaccination or therapeutic interventions using monoclonal antibodies or antivirals have been used to prevent and control the infection [ 1 ]. Amongst them, vaccination remains the only preventative measure and has been proven effective against SARS-CoV-2 infection from earlier variants [ 2 , 3 , 4 ] and remains effective at protecting from severe outcomes caused by newly emerged variants of concern (VOCs) [ 5 , 6 , 7 ]. Currently approved vaccines target predominantly the Spike glycoprotein (S), which is responsible for viral entry.…”