WASHINGTON • Top US infectious disease official Anthony Fauci said on Tuesday that it is possible for Covid-19 to be reduced to an endemic illness next year if the country ramps up vaccination rates.

Booster doses of the Covid-19 vaccines are vital for reaching that point, Dr Fauci said in an interview during the Reuters Total Health conference, which runs virtually from Monday to Thursday.

"To me, if you want to get endemic, you have got to get the level of infection so low that it does not have an impact on society, on your life, on your economy," he said.

"People will still get infected. People might still get hospitalised, but the level would be so low that we don't think about it all the time and it doesn't influence what we do."

To get there, he said, it would take a lot more people getting vaccinated and getting boosters.

If the United States makes boosters available for everyone, it is possible for the country to get control of the virus by the spring of next year, Dr Fauci added.

"Look what other countries are doing now about adopting a booster campaign virtually for everybody. I think if we do that, and we do it in earnest, I think by the spring we can have pretty good control of this."

Meanwhile, residents of Washington will no longer be required to wear masks indoors as of next week, except in certain places like schools and on public transport, the US capital's mayor said on Tuesday, as the city's coronavirus caseload levels off.

"Beginning Monday, Nov 22, DC will lift the current indoor mask mandate," Ms Muriel Bowser announced on Twitter.

Private businesses can continue to make their own rules, she said, adding that masks would also still be mandatory in ride-sharing vehicles, libraries, nursing homes, prisons and some city government offices.

Washington had put the mask mandate in place in late July, for both the vaccinated and unvaccinated, amid a surge in infections tied to the rise of the Delta variant of the coronavirus.

The city has implemented relatively strict measures to curb the spread of Covid-19, as compared with other places in the US.

However, the new guidance appears to be at odds with the standards set by the Centres for Disease Control and Prevention (CDC). The CDC still considers Washington to be an area of "substantial" Covid-19 community transmission and suggests that everyone wear masks in "public, indoor settings".

Separately, President Joe Biden's administration plans to pay more than US$5 billion (S$6.8 billion) for a stockpile of Pfizer's new Covid-19 pill, enough for about 10 million courses of treatment to be delivered in the next 10 months, according to people familiar with the agreement.

Senior federal health officials are counting on the drug to be a powerful weapon against Covid-19.

When given promptly to trial groups of high-risk unvaccinated people who developed symptoms of the disease, the drug sharply reduced the risk of hospitalisation and death.

Pfizer on Tuesday applied for federal authorisation of the drug on an emergency basis. A similar pill developed by Merck and Ridgeback Biotherapeutics could be authorised as soon as early next month, meaning pharmacies could have limited supplies on hand in weeks.

Pfizer's treatment is taken as a regimen of 30 pills over five days; Merck's requires 40 pills over five days.

The antiviral drugs have helped inspire hope among senior administration officials that the US will be able to curb the devastating toll from the Delta variant and its predecessors.

Some experts believe the worst of the coronavirus pandemic has passed in the country, in part because more than four out of every five Americans aged 12 and older are at least partially vaccinated.

Others say rates of infection have merely plateaued and could easily rebound, especially with the onset of winter.

After declining for more than a month, the daily average of cases has started creeping up.

"I do think that these new oral antivirals will change the way that Covid is managed," said Dr David Dowdy, associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

"These will help reduce the burden on hospitals and the death toll," he said, but added that "even without these pills, those numbers are going down".

REUTERS, AGENCE FRANCE-PRESSE, NYTIMES