Nearly one in 10 Americans, or more than 32 million people, are now fully vaccinated against the coronavirus, according to new figures from the Atlanta-based Centers for Disease Control and Prevention.

That’s not enough for herd immunity yet, but on Wednesday, President Joe Biden’s top health adviser told CNN if case rates keep dropping while more people are getting vaccinated, the nation will get “closer to being safe from another (case) surge.”

“You can never put your guard down completely,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. “(But) once you get a substantial proportion of the population vaccinated, that is a very, very strong defense against there being another surge.”

At the current pace of about 2 million shots per day, the U.S. could reach herd immunity by summer through vaccinations alone, according to a CNN analysis. Fauci has cited estimations that 70% and 85% of the population must be vaccinated to stop the spread.

Biden is announcing Wednesday the U.S. is buying an additional 100 million doses of the single-shot Johnson & Johnson coronavirus vaccine.

The drugmaker is already obligated to supply 100 million doses to the federal government by the end of June. The additional vaccine would be delivered in the months following. A White House official previewed the news on the condition of anonymity before the president’s remarks.

The U.S. is set to receive enough doses of the three approved vaccines by the middle of May to cover all adults. The surplus would ensure supply to cover young adults and children, pending the result of safety and efficacy trials. They could also be used as potential “boosters” to further protect against emerging virus variants, or be shared with allies overseas once Americans are protected.

Biden said the U.S. expects to take delivery of enough coronavirus vaccine for all adults by the end of May — two months earlier than anticipated — and he pushed states to get at least one shot into the arms of teachers by the end of March to hasten school reopenings.

Last week, Biden announced Merck will help produce rival Johnson & Johnson’s newly approved one-shot vaccine, likening the partnership between the two drug companies to the spirit of national cooperation during World War II.

Despite the stepped-up pace of vaccine production, the work of inoculating Americans could extend well into the summer, officials said, depending both on the government’s capacity to deliver doses and Americans’ willingness to roll up their sleeves.

Biden’s announcements quickly raised expectations for when the nation could safely emerge from the pandemic, but even as he expressed optimism, Biden quickly tempered the outlook.

“I’ve been cautioned not to give an answer to that because we don’t know for sure,” Biden said, before saying his hope for a return to normal was sometime before “this time next year.”

As Biden spoke, states across the country were moving to relax virus-related restrictions. This despite the objections of Fauci and the White House, who have warned against any relaxation of virus protocols until more Americans are vaccinated.

In Texas, GOP Gov. Greg Abbott recently moved to lift his state’s mask-wearing mandate and a host of other limitations. Michigan’s Democratic Gov. Gretchen Whitmer eased capacity limits on restaurants and public and residential gatherings.

The Biden administration has told governors to make preparations to administer even more doses in the coming weeks. More shots are also headed toward the federally backed program to administer doses in retail pharmacies, which federal officials believe can double or triple their pace of vaccination.

More than 800,000 doses of the J&J vaccine were distributed last week to pharmacies, on top of the 2.4 million they are now getting from Pfizer and Moderna.

Those pharmacies will be key in getting the vaccines into the arms of teachers — particularly in the roughly 20 states where they have not been prioritized for shots. The aim is to help reopen schools to better educate students who have been at risk of falling behind during the pandemic and reduce the burden on parents who have had to choose between child care and a job.

“Let’s treat in-person learning as the essential service that it is,” Biden said. Teachers will be able to sign up directly through participating retail pharmacies, the administration said.

White House press secretary Jen Psaki also announced last week the federal government was increasing supply of the Moderna and Pfizer vaccines to states next week to 15.2 million doses per week, up from 14.5 million previously. States will also receive 2.8 million doses of the J&J shot this week.

Officials have said J&J faced unexpected production issues with its vaccine and produced only 3.9 million doses before being cleared for use. J&J Vice President Richard Nettles told lawmakers on Capitol Hill last week that the company had faced “significant challenges” because of its “highly complex” manufacturing process.

Before the approval of the J&J shot, Biden had suggested that it would take until the end of July to have enough vaccine for every adult in the U.S.

Psaki said an “across-the-administration effort” was required to get the two historic rivals to work together on the vaccines, even though conversations between J&J and Merck have been going on for months.

“There’s a difference between conversations and it moving forward,” she said.

White House adviser Andy Slavitt said that Biden was preparing for all contingencies to speed the vaccine supply, and that the new May timeframe was achievable.

“We are not in the habit of overpromising,” he said.