U.S. officials authorize 4th dose of Pfizer COVID-19 shot for Americans 50 and up

U.S. regulators haveauthorized a fourth dose of Pfizer-BioNTech'sCOVID-19 vaccine for Americans 50 and older.

The U.S. Food and Drug Administration also authorized an additional boosterof the vaccine for people aged 12 and older with compromised immune systems, the regulatory body announced on Tuesday, with the U.S. Centers for Disease Control and Prevention (CDC) backing both uses.

"These updated recommendations acknowledge the increased risk of severe disease in certain populations including those who are elderly or over the age of 50 with multiple underlying conditions, along with the currently available data on vaccine and booster effectiveness," the CDC said in a statement.

During the recent Omicron surge, those who were boosted were 21 times less likely to die from COVID-19 compared to those who were unvaccinated, and seven times less likely to be hospitalized, CDC data shows.

TheCDC's updated recommendations will mean those at-riskindividuals who had a thirddose at least four months ago will be eligible for yet another mRNA booster "to increase their protection against severe disease from COVID-19."

Separately and in addition, based onnewly published data, adults who received a primary vaccine and booster dose of Johnson & Johnson's Janssen COVID-19 vaccine at least four months ago may now receive a second booster dose using an mRNA COVID-19 vaccine.

The authorization comes as some scientists have raised concerns about the highly contagious BA.2 Omicron subvariant, which has driven new spikes in COVID-19 cases in other countries.

COVID-19 cases in the United States have dropped sharply since a record surge in January, but have seen a small uptick over the past week, according to CDC data.

"While this EUA[emergency use authorization]will help address a current need for some, we're working diligently to develop an updated vaccine that not only protects against current COVID-19 strains, but also provides more durable responses," Pfizer chief executive Albert Bourla said in a statement.

Pfizer and BioNTech originally asked for the next booster doses to be authorized for people 65 and older in a submission citing data collected in Israel, where a second booster is already authorized for many people over age 18. The companies did not explain why the age range had been expanded.

Scientists and officials have debated whether young, healthy people will need a fourth shot. A study of Israeli health-care workers suggested that the fourth dose added little additional protection in the age group.

Biden administration officials have said that the U.S. government currently has enough doses of the vaccines to meet the demand for another round of booster shots in older Americans, even as funding for the U.S. pandemic response has all but run out.

They say that unless Congress approves more spending, the government willlikely not be able topay for future inoculations, if they are needed, particularly if the vaccines need to be redesigned to target new variants.

Here in Canada,fourth doses are already being offered to people in certainhigh-risk groups, such as residents of long-term care or those who are immunocompromised.