COVID-19 Vaccine Antigen Composition Update: Experts Recommend Ongoing Use of Monovalent JN.1 and KP.2 Vaccines

Strategic Insights -

The World Health Organization's (WHO) Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) has recommended the ongoing use of monovalent JN.1 and KP.2 vaccines against COVID-19. This decision is based on the analysis of evidence from various sources, including published and unpublished data, and considerations of the genetic and antigenic evolution of SARS-CoV-2 variants. The TAG-CO-VAC has also advised that monovalent LP.8.1 is a suitable alternative vaccine antigen.

The TAG-CO-VAC has extensively reviewed the available evidence, including SARS-CoV-2 genetic evolution, antigenic characterization of previous and emerging variants, immunogenicity data on neutralizing antibody responses elicited by currently approved vaccine antigens, and preliminary immunogenicity data on immune responses following infection with circulating SARS-CoV-2 variants. The results of this analysis have shown that the currently approved monovalent JN.1 or KP.2 vaccines continue to elicit broadly cross-reactive immune responses to circulating JN.1-derived variants.

Key Takeaways:

  • Monavalent JN.1 (NextStrain: 24A, GenBank: PP298019, GISAID: EPI_ISL_18872762) or KP.2 vaccines remain appropriate for ongoing use.
  • Monavalent LP.8.1 (NextStrain: 25A; GenBank: PV074550.1; GISAID: EPI_ISL_19467828) is a suitable alternative vaccine antigen.
  • Other approaches that demonstrate broad and robust neutralizing antibody responses or efficacy against currently circulating JN.1 descendent lineage variants could also be considered.
  • The TAG-CO-VAC appreciates the limitations of available data, including persistent gaps in the reporting of cases, hospitalizations, and deaths, as well as in genetic/genomic surveillance of SARS-CoV-2 globally.
  • The TAG-CO-VAC strongly encourages the generation of additional data on immune responses and clinical endpoints in varied human populations and strengthened epidemiological and virological surveillance.

Statistics:

  • 65 years and older and those with coexisting conditions continue to account for the majority of COVID-19 deaths.
  • Between the second half of 2024, when several monovalent JN.1 or KP.2 mRNA COVID-19 vaccines were introduced into vaccination programs, several of these vaccines have been approved for use by regulatory authorities.
  • The weekly proportion of Variant Under Monitoring (VUM) LP.8.1 among all SARS-CoV-2 sequences submitted to GISAID continues to increase.
  • The weekly proportion of JN.1 (Variant of Interest, VOI) is slowly increasing, largely due to increases in LF.7 and its descendent variants.

Sources:

  • World Health Organization (2025)
  • TAG-CO-VAC recommendations for COVID-19 vaccine antigen composition (2025)
  • GISAID (2025)
  • GenBank (2025)
  • WHO Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE)
  • WHO Coronavirus Network (CoViNet)
  • Global Influenza Surveillance and Response System (GISRS)