April 24, 2024

Importance of Continued Vaccine Monitoring Highlighted as SARS-CoV-2 Variants Evolve

A recent study conducted by researchers from the Francis Crick Institute and the National Institute for Health and Care Research Biomedical Research Centre at UCLH emphasizes the critical need for ongoing surveillance of emerging SARS-CoV-2 variants and vaccine efficacy as the virus continues to evolve. The findings of the study, published in The Lancet, underscore the importance of monitoring the performance of vaccines in response to new variants of the virus.

The study compared the effectiveness of the newer monovalent COVID vaccine, specifically targeting the XBB variant of omicron (as per WHO recommendation), with older bivalent vaccines that contained a mix of an omicron variant and the original strain of COVID-19, which were initially deployed in the UK in autumn 2023 before the shift to monovalent vaccines.

Researchers discovered that both types of vaccines produced neutralizing antibodies against the latest omicron strain, BA.2.86. However, the monovalent vaccine elicited higher levels of antibodies against various omicron variants compared to the bivalent vaccine.

The study involved collecting blood and nasal mucosal samples from 71 participants before and after receiving a fifth dose vaccination from the Legacy study, a collaborative research project between the Crick Institute and the NIHR University College London Hospitals Biomedical Research Centre. The analysis of antibody levels pre and post-vaccination revealed that both types of vaccines boosted antibody levels against all variants tested, including the newest strain BA.2.86. However, individuals vaccinated with the monovalent vaccine exhibited 3.5 times higher antibody levels against XBB and BQ.1.1 strains post-booster dose.

Given the high transmissibility of the omicron variant, particularly in the nose and throat, researchers measured antibody levels in the nasal cavity as well. The results showed that the monovalent vaccine enhanced the production of mucosal antibodies against most tested variants, while the bivalent vaccine did not show a significant increase.

In terms of neutralizing antibody levels in the nasal cavity against the latest variant, BA.2.86, neither vaccine demonstrated a substantial increase. This suggests that existing vaccines may be less effective in preventing transmission or mild illness, although they still offer protection against severe disease.

The study underscores the importance of continuous vaccine evaluation and the development of antibody therapeutics effective against all variants, especially for individuals who may not respond well to vaccines. Dr. Emma Wall, Senior Clinical Research Fellow at the Crick Institute and Consultant in Infectious Diseases at UCLH, stressed the need for vigilant monitoring as the virus evolves to ensure vaccine efficacy in the future.

Dr. David LV Bauer, Group Leader of the RNA Virus Replication Laboratory at the Crick, highlighted the significance of surveillance to keep pace with viral evolution. While new variants emerge rapidly, ongoing monitoring and laboratory analysis are essential to adapt to the changing landscape of the virus.

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