By William Elliott, MD, FACP, and James Chan, PharmD, PhD
The Food and Drug Administration (FDA) has approved and granted emergency use authorization (EUA) for updated messenger ribonucleic acid (mRNA) COVID-19 vaccines.1 The 2024-2025 formula is a monovalent component that corresponds to the Omicron variant KP.2 strain of SARS-CoV-2. The mRNA vaccines are distributed by Moderna TX Inc. as Spikevax and by Pfizer-BioNTech as Comirnaty.
Indications
COVID-19 mRNA vaccines are indicated for active immunization to prevent coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in individuals 12 years of age and older and EUA for individuals 6 months of age and older.2-5
Dosage
Comirnaty is administered intramuscularly as a single 0.3-mL dose. Each 0.3-mL dose is formulated to contain 30 mcg of a nucleoside-modified mRNA encoding the viral spike (S) glycoprotein of SARS-CoV-2 Omicron variant lineage KP.2. Spikevax is administration intramuscularly as a single 0.5-mL dose Each 0.5 mL contains 50 mcg nucleoside-modified messenger RNA (mRNA) encoding the pre-fusion stabilized spike glycoprotein (S) of the SARS-CoV-2 Omicron variant lineage KP.2.
For individuals previously vaccinated, the new vaccine should be administered at least two months after the last dose of COVID-19 vaccine.
Potential Advantages
The 2024-2025 formula (monovalent KP.2 strain of JN.1 lineage) is more closely matched to circulating SARS-CoV-2 strains and provides better protection against serious consequences of COVID-19, including hospitalization and death.1 This replaces the previous Omicron XBB.1.5-adapted COVID-19 vaccine. JN.1 shows robust resistance to XBB.1.5 vaccine.
When compared to last year’s vaccine, Pfizer’s KP.2 COVID-19 vaccine offered up to a 7.3-times stronger response in mice infected with KP.2 and several other JN variants.6 Moderna’s KP.2 vaccine was up to eight times more effective at protecting mice against JN variants than its XBB.1.5 vaccine.
Potential Disadvantages
The most commonly reported adverse reactions are pain at injection site (up to 90%), fatigue (58% to 78%), headache (42% to 76%), and myalgia (40% to 50%).2,3 Percentages vary based on the product and age of recipients.2,3 Post-marketing data suggest an increased risk of myocarditis and pericarditis within the first week following vaccination with the highest risk in males aged 12-17 years for Comirnaty and 18-24 years for Spikevax.2,3
Comments
While the vaccines are targeted to the KP.2 strain, which was dominant early in 2024, as of mid-August, this strain only represents < 5% of infections, with KP.3 and KP.3.1.1 making up more than 50% of cases. KP.2 is now in sixth place (3.2%) while its offspring dominate.7 Research has shown the updated vaccines are more effective at protecting against the JN lineage than the currently available XBB.1.5 vaccines, which were approved last year. The updated vaccines produced antibodies that can recognize JN.1 and its descendants.7
Clinical Implications
The global COVID-19 pandemic has been declared over. However, the virus continues spread and evolve elicited by vaccination and/or infection. As of Aug. 20, Omicron variants (descendants of JN.1) KP.2, KP.3, as well as LB.1 have a high prevalence in the United States. These result in mutations at key sites in the spike protein. KP.2 showed substantial resistance to sera of individuals vaccinated with last year’s vaccine (XBB.1.5). JN.1 has decreased binding affinity to the human angiotensin converting enzyme 2 receptor but appears to be more transmissible than other Omicron variants. However, it does not cause more severe disease than other variants.7
Previously infected and previously vaccinated individuals appear to have low or reduced neutralizing activity against JN.1. The potential for infection with an emerging variant of Omicron is substantial, even for individuals who have received the most recent COVID-19 vaccine updates. It appears that LB.1 and KP.2.3 exhibit higher infectivity and greater immune escape than KP.2 and KP.3.7 The Centers for Disease Control and Prevention is recommending that everyone 6 months of age and older receive an updated COVID-19 vaccine as well as a flu vaccine this fall. The FDA also has recently granted EUA to a non-mRNA, protein-based, adjuvanted vaccine targeted to JN1 (Novavax) for individuals aged 12 years and older. Paxlovid remains effective against the new variants as well.7
REFERENCES
- U.S. Food and Drug Administration. FDA approves and authorizes updated mRNA COVID-19 vaccines to better protect against currently circulating variants. Published Aug. 22, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-and-authorizes-updated-mrna-covid-19-vaccines-better-protect-against-currently
- U.S. Food and Drug Administration. Comirnaty prescribing information. Pfizer- BioNTech. Revised August 2024. https://www.fda.gov/media/151707/download
- U.S. Food and Drug Administration. Spikevax prescribing information. Moderna TX, Inc. Revised August 2024. https://www.fda.gov/media/155675/download
- U.S. Food and Drug Administration. Moderna COVID-19 vaccine. Revised Aug. 23, 2024. https://www.fda.gov/vaccines-blood-biologics/coronavirus-covid-19-cber-regulated-biologics/moderna-covid-19-vaccine
- U.S. Food and Drug Administration. Pfizer-BioNTech COVID-19 vaccine. Revised Aug. 23, 2024. https://www.fda.gov/vaccines-blood-biologics/coronavirus-covid-19-cber-regulated-biologics/pfizer-biontech-covid-19-vaccine
- Johnson A. FDA approves updated Novavax COVID vaccine week after approving Moderna and Pfrizer’s shots. Forbes. Published Aug. 30, 2024. https://www.forbes.com/sites/ariannajohnson/2024/08/22/fda-approves-updated-moderna-pfizer-covid-vaccines/
- COVID-19 Real-Time Learning Network. COVID-19 variant update. Published Sept. 17, 2024.https://www.idsociety.org/covid-19-real-time-learning-network/diagnostics/covid-19-variant-update/#/+/0/publishedDate_na_dt/desc/
The Food and Drug Administration has approved and granted emergency use authorization for updated messenger ribonucleic acid (mRNA) COVID-19 vaccines.
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