By Michael Erman

(Reuters) – U.S. regulators have approved a second booster of COVID-19, the most widely used vaccine for those over 50. The decision was made in light of data that shows waning immunity.

U.S. Food and Drug Administration announced that the fourth round of vaccine boosters for all recipients was now available. Pfizer (NYSE:) Inc/BioNTechSE and Moderna Inc vaccines should be administered no later than four months from the last dose. These vaccines are designed to provide greater protection from severe diseases and hospitalizations.

FDA has also approved the approval of a second dose booster for vaccines that are intended for young people with impaired immune systems. These include those 12 or older who received the Pfizer/BioNTech shot, as well as Moderna’s.

Scientists have expressed concern about the contagious BA.2 Omicron Subvariant. This has led to new COVID-19 cases elsewhere.

The number of COVID-19-related cases in the United States dropped significantly after a record January surge, but there has been a modest uptick since the week before, according to U.S. Centers for Disease Control and Prevention data.

Albert Bourla, chief executive of Pfizer said that the EUA (emergency-use authorization) will be a helpful solution to a need. However, it is still a work in progress. It provides protection against COVID-19 and also gives us more reliable responses.

BioNTech, Pfizer, and BioNTech requested the authorization of next booster doses for persons 65 or older. This submission was based on data from Israel. Many people above 18 years old have a second booster. FDA and companies did not elaborate on why this age range was expanded.

Officials and scientists have debated the need for a fourth dose in young healthy adults. An Israeli study found that the fourth dose provided little protection to the elderly.

Biden administration officials claimed that the U.S. has sufficient vaccines at the moment to provide booster shots to older Americans. However, funding for the U.S. response to the pandemic has nearly run out.

The government won’t be able pay future immunizations if Congress doesn’t approve more spending. This is especially true if vaccines have to be designed to target new varieties.