The U.S. has secured 200 million more doses of the coronavirus vaccine, President Joe Biden announced Thursday, guaranteeing the country will have enough shots on hand for 300 million Americans by the end of July.

Biden, who said last month that his administration was hoping to purchase more doses, made the announcement in remarks at the National Institutes of Health, where he thanked agency staff and was joined by Dr. Anthony Fauci and NIH Director Francis Collins.

The new agreements secure 100 million more doses of the Pfizer vaccine and 100 million more of the Moderna vaccine. That brings the expected U.S. supply to 600 millions doses, enough to vaccinate 300 million people total, since both vaccines require two rounds of shots.

“Now we’re working to get those vaccines into the arms of millions of people,” Biden said at the NIH on Thursday. 

More than 46 million people have gotten at least one dose of the vaccine so far, according to a CDC tracker. Biden has made it a goal to vaccinate 100 million Americans in his first 100 days – and the U.S. is on pace to exceed that goal.

"Like I said before, that’s just the floor," Biden said. "Our end goal is beating COVID-19."

The federal government has increased its weekly distribution of shots since Biden took office, and more than 1.4 million Americans are now getting vaccinated each day, according to a seven-day average.

On Thursday, President Biden also stressed the safety of the vaccine and the need for Americans to get the shot when it becomes available to them.

"I got my shots. My wife Jill did, Kamala did and her husband Doug did," he said. "It’s safe. We need more people to get vaccinated to beat this pandemic."

Biden kept his mask on as he spoke to NIH employees Thursday, which he said was partly to send a "critically important" message that masks save lives. He normally takes it off for speaking events.

"The masking is still the easiest thing to do to save lives," Biden said. "I know it's a pain in the neck. But it’s a patriotic responsibility. We’re in the middle of a war with this virus.”

"It’s a patriotic responsibility," Biden repeated, raising his voice. 

The president has challenged all Americans to wear masks for 100 days and has mandated them on federal property as well as for all domestic and international transportation. 

On Wednesday, the CDC published the results of lab experiments testing different ways of masking, including double masks and more tightly-fitted masks. Researchers found that when both subjects in the experiment wore proper face coverings 

Biden also took ample time to thank employees at the NIH in his Thursday remarks.

"You’re an incredible group of people,” he said. “I’ve been out here many times, trying to help my son, who passed away of cancer."

Earlier in the day, Biden toured the Vaccine Research Center, which oversees the development of vaccines for things like HIV/AIDS, Ebola and now COVID-19. The Moderna vaccine was co-developed with the National Institutes of Health. 

"You’re the best America has to offer," Biden said to NIH staff before leaving the stage. "Thank you, thank you, from the bottom of my heart."