A vial of SARS-CoV2 COVID-19 vaccine in a medical research laboratory

Federal health officials may authorize a half-dose of Moderna’s COVID-19 vaccine as a protective booster shot.

A 50-microgram dose appears to be effective enough to increase waning vaccine protection months after an initial series of two shots, sources familiar with the matter have told Bloomberg. A half-dose also may help lessen the risk for side effects and increase availability, the news outlet was told.

The news comes days after federal health agencies recommended that a third dose of Pfizer’s coronavirus vaccine be offered to older and medically vulnerable Americans, including healthcare workers. 

Currently, only people who have received the Pfizer vaccine are eligible for booster shots. The Moderna and Johnson & Johnson coronavirus vaccines, which received emergency use authorizations for their COVID-19 vaccines later in the pandemic than Pfizer’s drug, are currently being vetted for full federal approval and as boosters.

“We will address, with the same sense of urgency, recommendations for the Moderna and J&J vaccines as soon as those data are available,” CDC Director Rochelle P. Walensky, M.D., said Friday in her announcement regarding Pfizer boosters.

About 92% of all inoculated Americans have received either Pfizer’s or Moderna’s vaccines, Bloomberg reported. Many nursing home residents who are at the six-month point from their initial vaccinations and therefore eligible for a booster originally received either Pfizer’s or Moderna’s shots.

In related news:

Boosters recommended only for long-term care residents in Canada  Vaccine advisers to Canada’s health officials have recommended that residents of long-term care facilities, including those living in nursing homes, assisted living communities and residential care facilities be offered COVID-19 vaccine booster shots. The recommendation does not apply to older adults living in the community, sources have told CBC News. The next group of people who should be approved for booster shots should be seniors who rely on home care, sources said.

Colorado’s long-term care operators must host vaccine booster clinics before November  Long-term care facilities must schedule coronavirus booster shot vaccine clinics by the end of October, according to an extended public health order from the Colorado Dept. of Public Health and Environment, according to KKCO 11, an NBC News affiliate. Facility operators have until Oct.1 to schedule the clinics, which must take place before Oct. 25, the news outlet reported.