A World Health Organization vaccination advisory group has adjusted its guidance for COVID-19 vaccinations, prioritizing at-risk older adults and frontline healthcare workers, among others, for both initial shots and boosters. Countries should consider their specific context when deciding whether to vaccinate healthy children and adolescents, and whether to offer additional boosters to healthy middle-aged adults and children, it said. 

In a Tuesday update, the United Nations agency underscored what it said was the importance of vaccinating people who remain at risk of severe disease. The recommendations reflect the influence of the omicron variant and high levels of population immunity from infection and vaccination, the WHO stated.

Along with older adults and healthcare workers, its highest priority group for vaccination includes younger adults with significant comorbidities, immunocompromised people and pregnant people.

“Updated to reflect that much of the population is either vaccinated or previously infected with COVID-19, or both, the revised roadmap re-emphasizes the importance of vaccinating those still at-risk of severe disease, mostly older adults and those with underlying conditions, including with additional boosters,” said Hanna Nohynek, MD, PhD, chair of the WHO’s Strategic Advisory Group of Experts on Immunization (SAGE).

Booster recommendations

For the high priority group, SAGE calls for an additional booster dose at six to 12 months following the recipient’s last shot. The timing within that window should be based on factors such as age and health issues such as immunocompromising conditions, it said.

Notably, it does not recommend additional booster vaccinations beyond a primary series plus a first booster shot for adults aged 60 years and younger or children who do not have compromising health conditions. 

CDC’s guidance

In the United States, the Centers for Disease Control and Prevention recommends that all eligible people aged 6 months and older receive “the most recent booster dose recommended for them by CDC” at least two months after completion of an initial series of shots, with some exceptions for small children. 

The CDC’s independent advisers decided in February that the current evidence does not support more than one yearly dose of the currently recommended COVID-19 bivalent booster vaccine for older adults and other groups vulnerable to severe disease.

Notably, the effectiveness of COVID-19 mRNA vaccines is thought to decline significantly at about four to six months after the shot is received. With this and other potential issues in mind, the Advisory Committee For Immunization Practices (ACIP) also called for vaccine policy flexibility, allowing for more frequent doses for people who are vulnerable to severe disease.

Nursing home rates

In U.S. nursing homes, about 53% of residents are up-to-date on their COVID-19 shots, having received the current recommended booster, a bivalent shot designed to target the omicron variant, according to CDC data from March 19.

About 42% of the overall U.S. population aged 65 years and older has received the bivalent shot.

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