New York, Nov 10 : Drugmakers Pfizer and BioNTech said on Tuesday that they had asked the U.S. Food and Drug Administration (FDA) to authorize booster shots of their Covid-19 vaccine for all adults 18 years old and over, seeking to broaden who is eligible for a third shot. The move came as part of a long-running debate among experts over who should be eligible for booster shots. An FDA advisory panel voted against a request for all adults to have a booster in September, in what was "a blow to the (Joe) Biden administration's earlier announcement of widespread shots," said The Hill. Currently, people who get the Pfizer/BioNTech or Moderna Covid-19 vaccines six months ago or longer may get a booster if they are 65 or older; at risk of severe Covid-19 from a breakthrough infection because of a medical condition such as diabetes, kidney disease or pregnancy; or at risk because of living conditions or work, Xinhua news agency reported. The companies said the submission was based on results of a Phase 3 trial involving more than 10,000 participants. It found boosters were safe and had an efficacy of 95 percent against symptomatic Covid-19 compared with the two-dose vaccine schedule in the period when the highly transmissible Delta was the dominant strain. The new request from Pfizer and BioNTech came as "federal health officials have made clear their concern about waning immunity as the nation heads into the winter months," reported CNN. The Pfizer/BioNTech vaccine itself was already authorized for use in people from ages 5 to 15, and approved for people aged 16 and older. The FDA has not scheduled a meeting of its independent advisory committee for November, suggesting the agency may make a decision on the Pfizer-BioNTech on its own without seeking external advice, reported National Public Radio (NPR). On Tuesday, the U.S. Centers for Disease Control and Prevention updated that 224,257,467 people have received at least one dose of Covid-19 vaccine, making up 67.5 percent of the whole U.S. population; fully vaccinated people stood at 194,168,611, accounting for 58.5 percent of the total. A total of 25,368,545 people, or 13.1 percent of the fully vaccinated group, have received booster shots. /IANS