ACIP Recommends Monovalent COVID-19 Booster for Older Adults this Spring

Recommendation in response to persistently high hospitalization, low vaccine uptake

Adults aged 65 years and older should receive a booster dose of the 2023-24 COVID-19 monovalent vaccine this spring, according to new recommendations made Wednesday by the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC).¹

The ACIP committee vote was 11-1 in favor of the recommendation with one member abstaining.

Last year’s recommendation from the advisory group was for an optional additional dose.

"There are still roughly 20 000 people a week hospitalized for COVID and about 2000 deaths a week caused by the disease," Megan Wallace, DrPH, MPH, of the CDC's National Center for Immunization and Respiratory Diseases (NCIRD), told committee members on Wednesday, during the first of the 2-day ACIP meeting.² Even last summer, when reported numbers were at their lowest, the CDC estimates there were still as many as 500 deaths from COVID-19 each week.²

These data underscore the still somewhat unpredictable seasonality of the COVID-19 virus. While infection rates increase during respiratory virus season, along with influenza and RSV, the ongoing circulation of SARS-CoV-2 throughout the year leads to the persistently recorded morbidity and mortality.² In fact, new COIVD-19 hospitalizations have not fallen lower than 6000 per week over the past 12 months, Wallace emphasized in her presentation.² Evidence to recommendation

Older adults remain most vulnerable. According to the CDC adults in the 65 and older population continue to be disproportionately affected by the SARS-CoV-2 virus and accounted for more than half of hospitalizations for COVID-19 infection between October and December 2023.¹ This group made up roughly two-thirds of adults hospitalized for COVID-19 from the pandemic’s start in March 2020 to January 2024, according to a presentation during the meeting by Christopher Taylor, PhD, also of the NCIRD.³ He emphasized that the majority of those hospitalized were not vaccinated or not up-to-date with vaccination.³ Adults aged 75 years and older, according to CDC data, have the highest mortality rates from COVID-19.²

Highlighting these data, CDC Director Mandy Cohen, MD, MPH, said in a statement, "Most COVID-19 deaths and hospitalizations last year were among people 65 years and older. An additional vaccine dose can provide added protection that may have decreased over time for those at highest risk."¹

Low vaccine uptake + immunosenecence. According to CDC estimates, less than one-quarter (~22%) of US adults aged 18 years and older have received the COVID vaccine that was updated for the 2023-24 vaccination season, including fewer than half (~42%) of those aged 65 or older.²

The shot being recommended for the spring booster is the formulation approved by the US Food and Drug administration (FDA) in fall 2023 that targets the SARS-CoV-2 XBB.1.5 subvariant. The vaccine has been shown to be effective also against the JN.1 subvariant, responsible currently for more than 96% of new COVID infections in the US.²

While the early estimates of vaccine efficacy have yet to show substantial waning, the effect is expected, said epidemiologist Wallace.

“Although seroprevalence is at 98% or more for many people, she explained, more of those who are 65 and older have a vaccine seroprevalence of only 26%.”²

There is precedent for older adults receiving additional vaccine doses, Wallace added, and more importantly for the efficacy of the boosters.² She pointed to the recommendations following the dose in the fall of 2021 and again after the updated bivalent dose in fall 2022. Wallace also pointed out that the additional dose of the 2023-2024 vaccine is already recommended for anyone with moderate or severe immunocompromise.²

Vaccine confidence waning. Data from a recent National Immunization Survey presented at the Wednesday meeting by Kevin Chatham-Stephens, MD, MPH, readiness and response lead for the NCIRD, show that while most Americans still consider COVID-19 vaccination to be safe and important, overall confidence in the vaccine has dropped from nearly 84% in January 2022 to 69.6% last month.⁴ Perceptions about the risk associated with being infected by SARS-CoV-2 have shifted over time as well. According to the survey results, fewer adults now say they are moderately or very concerned about getting the virus; over half (55%) of those surveyed in January 2022 reported the level of concern vs just one-third (32.7%) in January 2024.⁴

At Wednesday's meeting, new data were shared that showed the 2023-2024 monovalent shot lowered the odds of being hospitalized with COVID-19 in otherwise healthy people 65 years and older by up to 54%.

The CDC will publish additional details on that research later today.

References

1. Older adults now able to receive additional dose of updated COVID-19 vaccine. News release. Centers for Disease Control and Prevention. February 28, 2024. Accessed February 20, 2024. https://www.cdc.gov/media/releases/2024/s-0228-covid.html