An Extra 2023–2024 COVID-19 Vaccine Dose for Adults 65 and Older: ACIP's February 2024 Recommendation

On September 12, 2023, CDC's Advisory Committee on Immunization Practices (ACIP) recommended the updated (2023–2024 Formula) COVID-19 vaccine — a monovalent XBB.1.5-based vaccine — for everyone 6 months and older. On February 28, 2024, it added a recommendation: everyone 65 and older should get one additional dose of any updated COVID-19 vaccine (Moderna, Novavax or Pfizer-BioNTech).

Why older adults

Serious COVID-19 has become less common, but it's still a threat — especially for older people.

• By February 3, 2024, the U.S. had recorded about 6.7 million COVID-19 hospitalizations and 1.1 million deaths.
• From October 2023 to January 2024, people 65 and older accounted for 67% of COVID-19 hospitalizations.
• From January 2023 to January 2024, COVID-19 death rates were highest in adults 75 and older, then 65–74.
• About 98%–99% of Americans have antibodies from infection, vaccination or both — but people 65 and older are less likely to have immunity from infection than adults 30–64.
• Immunosenescence — the immune system's decline with age — means weaker responses to new antigens and less robust immunity after infection or vaccination; the pool of naive T cells shrinks with age.

So older adults rely more on vaccination to restore immunity that may have waned, and may need more frequent doses.

Only 42% of adults 65 and older had received the updated vaccine by February 3, 2024. But they were more concerned about COVID-19 and more confident in the vaccine than younger adults: in a November 2023–January 2024 survey, 68.4% of those who'd had an updated dose said they definitely would get another if recommended, 27.2% probably would or weren't sure, and 4.4% probably or definitely wouldn't. Without a recommendation, people who couldn't pay out of pocket would have had little access to another dose.

The evidence

Effectiveness. There are no trial data on a second updated dose, but the first dose produces strong neutralizing antibodies and protects against JN.1 and other circulating variants. Early estimates show the updated vaccine improved protection against symptomatic infection, emergency and urgent care visits, and hospitalization. No substantial waning showed yet, but earlier vaccines suggest it's coming. Extra doses of earlier vaccines helped older adults:

In nursing home residents, a second booster within 60 days was 74% effective against severe outcomes (hospitalization or death) and 90% effective against death, compared with one booster.

Safety. Three years of monitoring show COVID-19 vaccines have a favorable safety profile. Anaphylaxis is rare; there's a rare risk of myocarditis and pericarditis, mostly in males 12–39. No new concerns have emerged for the updated vaccine, and side effects are less frequent and milder in people 65 and older. A statistical signal for ischemic stroke after the Pfizer-BioNTech bivalent vaccine in people 65 and older was investigated and showed no clear, consistent evidence of a problem, alone or given with flu vaccine; one study found the bivalent vaccine 47% effective in preventing COVID-19-related clots, strokes and heart attacks in that age group.

Cost. The base-case estimate was $255,122 per quality-adjusted life-year gained — more favorable for higher-risk groups such as people with underlying conditions or those 75 and older.

The ACIP work group met seven times from November 2023, using the Evidence to Recommendations framework; ACIP voted 11 to 1, with one abstention.

The recommendation

Full schedules: clinical considerations for COVID-19 vaccines.

Reporting side effects

Report adverse events to the Vaccine Adverse Event Reporting System (VAERS) at vaers.hhs.gov or 1-800-822-7967. For licensed COVID-19 vaccines in people 12 and older, report any clinically significant event even if you're not sure the vaccine caused it, and any vaccination errors; for vaccines under Emergency Use Authorization, providers must report certain events.

Sources

Based on Panagiotakopoulos L, Godfrey M, Moulia DL, et al., "Use of an Additional Updated 2023–2024 COVID-19 Vaccine Dose for Adults Aged ≥65 Years: Recommendations of the Advisory Committee on Immunization Practices — United States, 2024," MMWR volume 73, number 16, Centers for Disease Control and Prevention; a work of the United States government in the public domain.