Researchers from the Francis Crick Institute and the Biomedical Research Center at the National Institute for Health and Care Research at UCLH have highlighted the importance of continued surveillance of emerging SARS-CoV-2 variants and vaccine performance as they emerge. the virus continues to evolve.
Published today as a research letter in The lancetTheir study compared the newer monovalent COVID vaccine, which specifically targets the Omicron XBB variant (as recommended by the World Health Organization), with older bivalent vaccines that contain a mixture of an Omicron variant and the strain original of COVID-19, which the United Kingdom will implement in autumn 2023 before turning to monovalent vaccines.1.
The researchers found that both vaccines generated neutralizing antibodies against the most recent strain of Omicron, BA.2.86. However, the new monovalent vaccine generated higher levels of antibodies against a variety of other Omicron variants.
The team collected blood and nasal mucosa samples before and after a fifth vaccination dose from 71 participants in the Legacy study, a research collaboration between Crick and the University College London Hospitals Biomedical Research Center NIHR. They compared antibody levels before and after vaccination.
All 36 participants who received the bivalent vaccine and 17 who received the monovalent vaccine had elevated levels of antibodies against all variants tested, including the newer strain BA.2.86, which caused a wave of infection this winter. But those with the newer monovalent vaccine had 3.5 times higher levels of antibodies against the XBB and BQ.1.1 strains after the booster vaccination.
Since the Omicron virus is highly transmissible and replicates in the nose and throat, the researchers tested antibody levels in the participants’ nasal cavity.
They found that the monovalent vaccine increased their ability to produce mucosal antibodies against most of the variants tested, while the bivalent vaccine did not provide a significant boost.
Neither vaccine increased levels of neutralizing antibodies in the nasal cavity against the newer variant, BA.2.86, suggesting that current vaccines are less likely to stop transmission or prevent asymptomatic or mild illness, while also protecting against disease. serious.
This highlights the importance of carefully updating vaccines and continuing to complement a vaccination program with the development of antibody drugs that work against all variants, as some more vulnerable people do not respond well to vaccines.
Emma Wall, Crick senior clinical researcher and infectious diseases consultant at UCLH, said: “The UK’s strategy of deploying older vaccine stocks paid off last year, with both vaccines providing equal protection against the strain. However, continued monitoring is necessary as the virus continues to evolve, so vaccine-induced antibodies may not work as well in the future. In the long term, vaccines are needed that are effective against all new variants and can block human-to-human transmission of COVID-19. “They are needed.”
David LV Bauer, group leader at the RNA Virus Replication Laboratory at the Crick, said: “The situation this winter could have been different if the newly emerged BA.2.86 and JN.1 variants were substantially different from the older Omicron variants. , but fortunately this was not the case.
“Most new variants emerge faster than most clinical trials can produce data. But laboratory analyzes can provide a detailed picture very quickly. Continued surveillance will help us stay on top of viral evolution” .