WALENSKY: "This was a scientific close call. In that situation, it was my call to make."The U.S. Centers for Disease Control and Prevention on Friday backed a booster shot of the Pfizer and BioNTech COVID-19 vaccine for Americans aged 65 and older, adults with underlying medical conditions and adults in high-risk working and institutional settings.The decision by CDC Director Rochelle Walensky is aligned with the U.S. Food and Drug Administration's authorization for a booster shot earlier this week but goes against a CDC panel's recommendation for a narrower booster rollout. Walensky's decision paves the way for not only the elderly to get the booster shot, but also teachers, health care workers, and anyone in a high-risk job.President Joe Biden on Friday said the U.S. is ready to give out the dose."We bought enough booster shots and states and pharmacies, doctors offices and community health centers have been preparing to get shots and arms booster shots and arms for a while. And like your first and second shot, the booster shot is free and easily accessible."Scientists have been divided over the need for booster shots for the COVID-19 vaccine, with some including those from the FDA and the World Health Organization saying there is inadequate evidence that they are needed by anyone other than older people.Pfizer and U.S. health officials have argued that the shots prevent hospitalizations and deaths and that emerging data indicates they can slow mild infections as well.Walensky on Friday defended her decision to overrule her own agency's advisors, saying it was to protect healthcare and frontline workers and ensure equity."Many of our frontline workers, essential workers, and those in congregate settings, come from communities that have already been hardest hit..."Biden said people should not be taken their chances, and since he's older than 65 - he'll be getting the booster. "I'll be getting my booster shot. Hard to acknowledge I'm over 65, but I'll be getting my booster shot. It's a bear and I tell you now. But all kidding aside, I'm getting my booster shot. I'm not sure exactly when I'm going to do it, as soon as I can get it done." And he urged others to do the same. But for now - that only applies to people who originally received the Pfizer vaccine. Officials are still waiting for data from Moderna and Johnson & Johnson before recommending another dose of their vaccines.