The emergence of several new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in recent months has raised concerns around the potential impact on ongoing vaccination programs. Data from clinical trials and real-world evidence suggest that current vaccines remain highly effective against the alpha variant (B.1.1.7), while some vaccines have reduced efficacy and effectiveness against symptomatic disease caused by the beta variant (B.1.351) and the delta variant (B.1.617.2); however, effectiveness against severe disease and hospitalization caused by delta remains high.

The coronavirus 19 (COVID-19) pandemic triggered a simultaneous global demand for preventative vaccines, which quickly became a high priority among governments as well as academia and the pharmaceu...

The highly transmissible Omicron (B.1.1.529) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first detected in late 2021. Initial Omicron waves were primarily made up of sub-lineages BA.1 and/or BA.2, BA.4, and BA.5 subsequently became dominant in mid-2022, and several descendants of these sub-lineages have since emerged. Omicron infections have generally caused less severe disease on average than those caused by earlier variants of concern in healthy adult populations, at least, in part, due to increased population immunity. Nevertheless, healthcare systems in many countries, particularly those with low population immunity, have been overwhelmed by unprecedented surges in disease prevalence during Omicron waves. Pediatric admissions were also higher during Omicron waves compared with waves of previous variants of concern. All Omicron sub-lineages exhibit partial escape from wild-type (Wuhan-Hu 1) spike-based vaccine-elicited neutralizing antibodies, with sub-lineages with more enhanced immuno-evasive properties emerging over time. Evaluating vaccine effectiveness (VE) against Omicron sub-lineages has become challenging against a complex background of varying vaccine coverage, vaccine platforms, prior infection rates, and hybrid immunity. Original messenger RNA vaccine booster doses substantially improved VE against BA.1 or BA.2 symptomatic disease. However, protection against symptomatic disease waned, with reductions detected from 2 months after booster administration. While original vaccine-elicited CD8⁺ and CD4⁺ T-cell responses cross-recognize Omicron sub-lineages, thereby retaining protection against severe outcomes, variant-adapted vaccines are required to expand the breadth of B-cell responses and improve durability of protection. Variant-adapted vaccines were rolled out in late 2022 to increase overall protection against symptomatic and severe infections caused by Omicron sub-lineages and antigenically aligned variants with enhanced immune escape mechanisms.

Immunization programmes have been globally recognized as one of the most successful medical interventions against infectious diseases. Despite the proven efficacy and safety profiles of coronavirus disease 2019 (COVID-19) vaccines, there are still a substantial number of people who express vaccine hesitancy. Factors that influence vaccine decision-making are heterogenous, complex, and context specific and may be caused or amplified by uncontrolled online information or misinformation. With respect to COVID-19, the recent emergence of novel variants of concern that give rise to milder disease also drives vaccine hesitancy. Healthcare professionals remain one of the most trusted groups to advise and provide information to those ambivalent about COVID-19 vaccination and should be equipped with adequate resources and information as well as practical guidance to empower them to effectively discuss concerns. This article seeks to summarize the currently available information to address the most common concerns regarding COVID-19 vaccination.

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to urgent actions by innovators, vaccine developers, regulators, and other stakeholders to ensure public access to protective vaccines while maintaining regulatory agency standards. Although development timelines for vaccines against SARS-CoV-2 were much quicker than standard vaccine development timelines, regulatory requirements for efficacy and safety evaluations, including the volume and quality of data collected, were upheld. Rolling review processes supported by sponsors and regulatory authorities enabled rapid assessment of clinical data as well as emergency use authorization. Post-authorization and pharmacovigilance activities enabled the quantity and breadth of post-marketing safety information to quickly exceed that generated from clinical trials. This paper reviews safety and reactogenicity data for the BNT162 vaccine candidates, including BNT162b2 (Comirnaty, Pfizer/BioNTech COVID-19 vaccine) and bivalent variant-adapted BNT162b2 vaccines, from preclinical studies, clinical trials, post-marketing surveillance, and real-world studies, including an unprecedentedly large body of independent evidence.