Under section 564 of the Federal Food, Drug, and Cosmetic Act (FD&C Act), the FDA Commissioner may allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or nuclear threat agents when there are no adequate, approved, and available alternatives. Vaccines that receive an EUA may later be fully licensed by the FDA.
COVID-19 vaccines were originally administered under EUA. All available 2026–2027 COVID-19 vaccines are fully licensed by FDA and no longer administered under EUA.
Last reviewed:
October 18, 2026
The Pfizer-BioNTech COVID-19 Vaccine (Comirnaty) and the Moderna COVID-19 vaccines (Spikevax, mNexspike) are lipid nanoparticle-formulated, nucleoside-modified mRNA vaccines encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. The 2026–2027 mRNA vaccines target the Omicron JN.1-lineage XFG strain. Moderna’s mNexspike was first licensed in 2025 for ages 12 years and older. It is designed to reduce the amount of mRNA required to elicit the same or slightly better immune response compared to Spikevax (10 mcg of mRNA versus 50 mcg of mRNA for an adult dose). CDC states that Spikevax and mNexspike may be used interchangeably when both are age appropriate. Visit the Children’s Hospital of Philadelphia (CHOP) Vaccine Education Center website for more details, including short videos, about how mRNA vaccines work: www.chop.edu/vaccine-education-center/science-history/vaccine-science/how-are-vaccines-made#mrnavaccines.
Last reviewed:
October 18, 2026
Spikevax and mNexspike are both mRNA vaccines targeting the same strain of COVID-19. Spikevax is the original vaccine now licensed down to age 6 months. The mNexspike product is a newer mRNA vaccine licensed for ages 12 years and older with an advanced design that achieves the same or slightly better immune response with less mRNA in each dose (10 mcg in mNexspike compared to 50 mcg in adult doses of Spikevax). CDC states that the two products may be used interchangeably when age appropriate.
For anyone recommended to receive a second dose 6 months after their first 2026–2027 dose (including all adults age 65 years and older), the minimum interval between the two recommended 2026–27 season doses is 3 months for mNexspike, but only 2 months for the other COVID-19 vaccine products. If mNexspike is inadvertently administered after only 2 months, the dose counts as valid and does not need to be repeated.
Last reviewed:
October 18, 2026
They are only interchangeable for people age 12 years or older. Spikevax and mNexspike are both mRNA-based COVID-19 vaccines manufactured by Moderna. Spikevax is given as a 0.25 mL (25 mcg) dose for ages 6 months through 11 years and 0.5 mL (50 mcg) for ages 12 years and older. The mNexspike dose as 0.2 mL (10 mcg) for ages 12 years and older. Each of these three options is packaged as a manufacturer-filled syringe in the United States. It is important to verify the product name, age indication, and dose volume before every injection.
Last reviewed:
October 18, 2026
Last reviewed:
January 9, 2026
The original COVID-19 vaccines all targeted the spike protein of the original SARS-CoV-2 virus. The 2026–2027 formulation vaccines target the spike protein of the Omicron JN.1-lineage XFG strain for all four products. The update is intended to boost production of antibodies that protect more effectively against disease caused by currently circulating Omicron subvariants.
The process of updating the strain without changing anything else is similar to the seasonal strain changes made for influenza vaccinations each year. Vaccine safety, side effects, and risk of allergic reactions are expected to be comparable to earlier formulations of vaccines of the same brand and dose. As with seasonal influenza vaccines, future COVID-19 vaccines can continue to be updated when needed, as the circulating viruses evolve.
Last reviewed:
October 18, 2026
No. The last U.S. doses of Janssen COVID-19 Vaccine expired May 7, 2023.
Last reviewed:
October 18, 2026
Nuvaxovid is the brand name of the adjuvanted protein subunit COVID-19 vaccine developed by Novavax and commercialized by Sanofi beginning in the 2025–26 season. It contains the Omicron JN.1-lineage XFG variant SARS-CoV-2 spike protein and Matrix-M adjuvant. The saponin-based adjuvant is made from extracts of the bark of the Soapbark tree native to Chile. It is added to enhance the immune response of the vaccine recipient. The spike protein is produced in insect cells.
The 2026–2027 formulation of Nuvaxovid is FDA-licensed for people age 65 years and older and people age 12 through 64 years with at least one condition that increases the risk of severe COVID-19. For people who are not moderately or severely immunocompromised, CDC’s schedule calls for a single dose at ages 12 through 64 years, given at least 8 weeks after the most recent dose of COVID-19 vaccine, regardless of the recipient’s vaccination history. CDC recommends that immunocompetent people age 65 years or older, and immunocompromised people age 12 years and older who completed an initial series before this season, receive 2 doses of 2026–2027 COVID-19 vaccines, 6 months apart (with a minimum interval of 2 months between doses if using Nuvaxovid for both doses).
CDC and the Infectious Diseases Society of America (IDSA) recommends a 2-dose initial series for previously unvaccinated recipients who are moderately or severely immunocompromised, with the doses given at least 3 weeks apart. A third dose of any age-appropriate COVID-19 vaccine is recommended 6 months after the initial series is completed (with a minimum interval of 2 months between doses if using Nuvaxovid).
Last reviewed:
October 18, 2026
The benefit of COVID-19 vaccination to an individual patient varies depending on the health status of the patient, their history of vaccination and COVID-19 infection, and the circulating COVID-19 strains. Observational studies show that updated vaccination provides additional protection against medically attended and severe COVID-19.
A CDC-led VISION study of immunocompetent adults age 18 years and older during September through December 2025 estimated effectiveness of 2025–2026 COVID-19 vaccination at 50% against COVID-19-associated emergency department or urgent care visits and 55% against hospitalization, compared with not receiving a 2025–2026 dose: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2850668.
CDC’s pediatric VISION report, published December 11, 2025, estimated effectiveness of 2024–2025 COVID-19 vaccination against emergency department or urgent care visits at 76% for immunocompetent children age 9 months through 4 years and 56% for those age 5 through 17 years during the first 7–179 days after vaccination: www.cdc.gov/mmwr/volumes/74/wr/mm7440a1.htm. These estimates describe the formulations in use at that time, not the 2026–2027 XFG formulation.
Last reviewed:
October 18, 2026
