• White House health advisor Dr. Anthony Fauci said on Tuesday that he expects most Americans will have access to a Covid-19 vaccine by mid- to late May or early June.
• That's a slight delay from previous predictions of late March to early April.
• The delayed timeline comes after Johnson & Johnson, which has applied for emergency use in the U.S., cut its initial supply estimates, Fauci said.

Most Americans will have access to a Covid-19 vaccine by mid- to late May or early June, White House chief medical advisor Dr. Anthony Fauci said on Tuesday, a slight delay compared with earlier predictions.

The infectious disease expert had previously forecast the lifesaving drugs would be widely available to the general public by late March or early April. So far, distribution of the vaccines has been limited to workers in essential industries, those age 65 and older and those with underlying health conditions, depending on the state.

However, Fauci said the federal government was expecting "considerably more" initial doses from Johnson & Johnson, which has applied for an emergency authorization in the U.S. The New Jersey-based company has previously said it will provide the U.S. with 100 million doses by the end of June.

"It may take until June, July and August to finally get everybody vaccinated," Fauci told CNN on Tuesday. "So when you hear about how long it's going to take to get the overwhelming proportion of the population vaccinated, I don't think anybody disagrees that that's going to be well to the end of the summer and we get into the early fall."

The New York Times first reported in January that unexpected manufacturing delays would lead to a reduced initial supply of J&J's drug if it is given emergency authorization. A spokesperson for the company was not immediately available to comment on how many doses J&J will immediately provide.

The Biden administration has steadily increased the number of doses sent to states every week, announcing plans on Tuesday to ship 13.5 million doses this week. The federal government will also double the number of doses shipped directly to retail pharmacy chains, White House press secretary Jen Psaki said.

Demand for the drugs still far outweighs the nation's supply, Fauci told CNN, calling it a "critical issue." For weeks, state health officials have demanded a more steady supply of vaccines. Some large-scale mass vaccination sites in the U.S. have had to delay their opening or temporarily close due to a shortage of doses.

"I'm a little disappointed that the number of doses that we're going to get early on from J&J are relatively small, but as we get further into the spring there will be more and more," Fauci said.

Meanwhile, the head of the United Kingdom's vaccine task force told Sky News on Tuesday that he expects every adult there could receive both doses of vaccine by August or September.

"We are confident within the vaccine task force now that the supply we're going to get will take us to a position where we can vaccinate as many people as the U.K. wants to vaccinate," Clive Dix told Sky News.