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London, March 13, 2024 (Health News): As the SARS-CoV-2 virus continues to undergo genetic changes, researchers from the Francis Crick Institute and the National Institute for Health and Care Research Biomedical Research Centre at UCLH have emphasized the critical importance of ongoing surveillance of emerging variants and vaccine effectiveness. Their findings, published today in a research letter in The Lancet, shed light on the comparative performance of different COVID-19 vaccine formulations against evolving Omicron variants.
The study compared the efficacy of newer monovalent COVID vaccines, targeting the XBB variant of Omicron as recommended by the World Health Organization, with older bivalent vaccines containing a mix of Omicron variants and the original strain of COVID-19. Drawing from the Legacy study—a collaboration between the Crick and the NIHR University College London Hospitals Biomedical Research Centre—the researchers collected and analyzed blood and nasal mucosal samples from 71 participants before and after a fifth dose vaccination.
Results indicated that both vaccine types generated neutralizing antibodies against the most recent Omicron strain, BA.2.86. However, participants who received the monovalent vaccine exhibited significantly higher levels of antibodies against a broader range of Omicron variants compared to those who received the bivalent vaccine. Specifically, individuals with the monovalent vaccine had 3.5 times higher antibody levels against the XBB and BQ.1.1 strains post-boost.
Importantly, the study also evaluated mucosal antibody responses in the nasal cavity—an area critical for blocking viral transmission. While the monovalent vaccine enhanced mucosal antibody production against most tested variants, the bivalent vaccine did not provide a significant boost. However, neither vaccine demonstrated increased neutralizing antibody levels in the nasal cavity against the newest BA.2.86 variant, suggesting potential limitations in preventing transmission or asymptomatic/mild illness despite protection against severe disease.
Emma Wall, Senior Clinical Research Fellow at the Crick and Consultant in Infectious Diseases at UCLH, underscored the need for ongoing vigilance and adaptive vaccination strategies. “The evolving nature of the virus underscores the importance of continual monitoring and updates to vaccination strategies,” Wall stated. “In the long run, vaccines that effectively target all variants and interrupt transmission are essential.”
David LV Bauer, Group Leader of the RNA Virus Replication Laboratory at the Crick, highlighted the significance of rapid laboratory analysis in navigating viral evolution. “Continued surveillance is vital for staying ahead of viral mutations,” Bauer affirmed. “While clinical trials may lag behind new variants, laboratory analysis offers timely insights to inform adaptive responses.”
The study’s findings provide crucial insights for policymakers and public health officials in optimizing vaccination strategies and developing effective interventions against emerging SARS-CoV-2 variants.
