Johnson & Johnson board member Dr. Mark McClellan told CNBC Friday that there could be enough vaccinations for the entire U.S. adult population by the summer. 

“Assuming all of the close review of the J&J data all pans out, we’re going to have the capacity between Moderna, Pfizer, J&J, to have enough vaccines available by June for the entire U.S. adult population,” McClellan, a former FDA commissioner, said on “The News with Shepard Smith.” 

The U.S. plans to buy 200 million Covid vaccine doses from Moderna and Pfizer. The Department of Health and Human Services will boost its vaccine supply to states from 8.6 million to a minimum of 10 million doses per week. So far, states have received more than 49 million doses, but only about half of those have actually ended up in people’s arms, according to the Centers for Disease Control and Prevention. The agency reports that the U.S. is administering a little more than a million shots every day.

McClellan that the U.S. should significantly increase the amount of shots administered per day and “get our capacity for doing vaccinations up closer to 3 million doses per day.”

The United States has ordered 100 million doses of the J&J vaccine, which the company plans to deliver by June. J&J plans to file for emergency use authorization next week. If J&J’s vaccine is authorized by the FDA, it would be the third vaccine approved for emergency use in the U.S. Pfizer’s vaccine was authorized by the FDA on Dec. 11, and Moderna’s was authorized a week later.

The J&J vaccine efficacy numbers were lower than those for Pfizer and Moderna. Pfizer’s vaccine was found to be 95% effective against preventing Covid-19, while Moderna’s was found to be about 94% effective. J&J’s vaccine was found to be 66% effective overall in preventing moderate to severe Covid.

Host Shepard Smith asked McClellan about the lower efficacy numbers compared to Pfizer and Moderna, and he explained to Smith that “we’re fighting a different virus today than we were three months ago when previous trials were done.”

Additionally, J&J ran its trial across three continents and the level of protection varied by region. Its vaccine demonstrated overall, 72% effectiveness in the United States and 66% in Latin America. In South Africa, where the dangerous B.1.351 strain of Covid caused a surge in cases, the J&J  vaccine demonstrated 57% effectiveness.

“Unfortunately, we’re probably going to be fighting a different virus three months from now, so most important in winning this battle, is getting as many people vaccinated as possible,” said McClellan. “The faster we get shots in arms, the more people we get vaccinated here in this country and around the world, the better we’re going to do in containing that further spread and the further damage from Covid.”