There were significant declines in vaccine efficacy in individuals ages 65 and over, including residents of long-term care facilities, found mRNA vaccination products, according to data presented today by Ruth Link-Gelles, a CDC epidemiologist who is co-lead of the agency’s vaccine effectiveness team.

Link-Gelles addressed the CDC’s Advisory Committee on Immunization Practices (ACIP) as it began its two-day deliberations on a Pfizer Inc.-Biontech booster dose for those ages 65 and older along with those at high risk for developing severe COVID-19. One of ACIP’s goals is identifying who belongs in the high-risk category.

There were more declines in hospitalized patients receiving the Pfizer vaccine than Moderna Inc.’s in the time frame that finds the Delta variant dominating the pandemic, according to Link-Gelles’ data. There was no vaccine efficacy data found against infection for those with underlying conditions, she told ACIP. There were similar patterns of efficacy found in long-term care facility residents as those found in the general adult population, she added.

As for the exposure of those in high-risk occupations, no data were available, Link-Gelles said, but she added that its risk was likely similar to that of the overall population.

Vaccinating long-term care staff is a critical tool for preventing COVID-19 cases in nursing homes, Rachel Slayton, a CDC epidemiologist and infectious disease modeler, told the ACIP committee. Boosters, she said, would help in the fight to reduce cases in nursing homes. But even with boosters that contain high efficacy, cases in nursing homes will persist when community transmission remains high.

Slayton cited data showing that most COVID-19-infected individuals among vaccinated residents are asymptomatic due to vaccine efficacy against symptomatic disease while only 20% of residents are unvaccinated. Those residents contribute a large share of the symptomatic cases, she added.

Higher staff coverage and higher booster efficacy, Slayton said, leads to fewer infections. Community transmission, she added, is a key driver of COVID-19 infection cases in nursing homes.