Article image

Monitoring COVID vaccines is crucial as virus keeps mutating

The relentless enemy, COVID-19, continues to mutate, throwing up new variants that challenge our defenses. However, science evolves too, adapting our strategies and tools to keep pace with this ever-changing adversary.

A recent study by the Francis Crick Institute brings new insights to this dynamic battlefield. The experts emphasize the importance of COVID vaccine monitoring as the SARS-CoV-2 virus continues to evolve.

Monovalent and bivalent COVID vaccines

At the heart of the recent study is a comparison between two types of COVID-19 vaccines: monovalent and bivalent.

  • Monovalent vaccines: These target a specific variant, currently the XBB omicron variant which is widely circulating. This targeted approach aims to create a strong immune response against this dominant strain.
  • Bivalent vaccines: Unlike monovalent vaccines, these offer broader protection. They contain components from two different strains – the original virus and an earlier omicron variant.

In late 2023, the World Health Organization (WHO) underscored the need for vaccines to be updated to effectively target the XBB variant of Omicron and its descendants. This guidance led countries like the UK to deploy monovalent vaccines that specifically target this variant, a strategic pivot from the previously used bivalent vaccines that included an Omicron variant and the original COVID-19 strain.

This shift was based on evidence suggesting that the monovalent vaccine induced higher antibody binding titers and neutralization activities against a broader range of Omicron variants.

Superiority of monovalent vaccine

The experts analyzed blood and nasal mucosal samples from 71 participants, before and after their fifth dose of the vaccine. The research revealed that both vaccine types were effective in producing neutralizing antibodies against the latest Omicron strain, BA.2.86. Notably, the monovalent vaccine demonstrated a superior ability to generate higher antibody levels against various Omicron strains.

All participants saw their antibody levels rise against every tested variant, BA.2.86 included. Yet, those who received the monovalent vaccine had a 3.5 times greater increase. This boost even targeted strains such as XBB and BQ.1.1.

Limited mucosal antibody response

The Omicron variant spreads easily and replicates in the nose and throat. This study also examined mucosal antibodies in response to the COVID vaccines and the findings were mixed. The monovalent vaccine enhanced the production of mucosal antibodies against most tested variants. However, the bivalent did not boost the mucosal antibody levels.

Crucially, neither COVID vaccine type significantly increased neutralizing antibody levels in the nasal cavity against the BA.2.86 variant. This indicates a possible weakness in our defense, and underscores the urgency of updating vaccines and creating antibody drugs. These measures aim to safeguard the most vulnerable, especially those less responsive to vaccines.

Ongoing monitoring is needed

Emma Wall, senior clinical research fellow at Crick and Consultant in Infectious Diseases at UCLH, emphasized the success of the UK’s strategy to utilize older vaccine stocks.

“The UK’s strategy to deploy stocks of older vaccines paid off last year, as both vaccines provided equal protection against the newest strain. However, ongoing monitoring is needed, as the virus is continuing to evolve, so vaccine-induced antibodies might not work so well in the future,” said Wall.

“In the long run, vaccines that are effective against all new variants and can block COVID-19 being transmitted from person to person are needed.”

Staying on top of viral evolution

David LV Bauer, group leader of the RNA Virus Replication Laboratory at Crick, added: “The situation this winter could have been different if the newly emerged BA.2.86 and JN.1 variants were substantially distinct from older Omicron variants, but fortunately this wasn’t the case.”

“Most new variants arise quicker than most clinical trials can produce data. But laboratory analysis can provide a detailed picture very quickly. Continued surveillance will help us stay on top of viral evolution.”

Adapting to the variants

Scientists are urging continued caution as the COVID-19 virus continues to mutate. The research emphasizes the need to adapt strategies alongside the evolving virus.

Through close monitoring and the development of new vaccines, researchers are striving to stay ahead of this global challenge. The journey may be long, but with ongoing research, scientists are hopeful for a future where COVID-19’s impact is significantly reduced.

The study is published in the journal The Lancet.


Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. Check us out on EarthSnap, a free app brought to you by Eric Ralls and


News coming your way
The biggest news about our planet delivered to you each day