WASHINGTON (NYTIMES) - President Joe Biden's coronavirus response team warned Americans on Tuesday (July 12) that they must do more to protect themselves against Covid-19 as the highly transmissible Omicron subvariant known as BA.5 fuels a new wave of infections, reinfections and hospitalisations across the country.

But their new strategy to combat the threat sounded a lot like the old one, couched as advice that they hope more Americans will start following: Get vaccinated or boosted even if you have already been infected, test if you feel sick, seek out therapeutics if you test positive, and wear masks in crowded indoor spaces.

"Variants will continue to emerge if the virus circulates globally and in this country," Dr Anthony Fauci, Mr Biden's chief medical adviser for the pandemic, said at a White House news briefing.

"We should not let it disrupt our lives. But we cannot deny that it is a reality that we need to deal with."

The subvariant BA.5 has recently become dominant among new US cases. The Centres for Disease Control and Prevention (CDC) estimated on Tuesday that it accounts for more than 60 per cent of all new infections.

The White House has been watching as BA.5 has marched across Europe and South Africa; experts say it appears to be able to evade some antibodies from previous infections and vaccines, though they say there is no evidence it causes more severe disease.

"The key feature of BA.5, that we know about, is its immune evasiveness; you can be fully vaccinated and boosted and still have a risk of a breakthrough infection," Dr Ashish Jha, Mr Biden's coronavirus response coordinator, said in an interview on Monday.

"You can be previously infected - even as recent as the last couple of months - and have a very high rate of reinfection."

As part of the strategy to combat BA.5, federal officials are considering expanding eligibility for second coronavirus booster shots to adults younger than 50, according to several people familiar with the thinking. But those decisions will be made by the Food and Drug Administration (FDA) and the CDC, and Dr Jha was cautious in discussing the idea during the briefing.

A White House fact sheet said the administration would continue to work with state and local leaders to drive an increase in the number of Americans taking booster shots, with a particular focus on those age 50 and older and those who are vulnerable. Fewer than half of those vaccinated have received their first booster, according to the CDC, and just 28 per cent of those older than 50 have received a second booster.

Officials are advising those eligible for boosters to get them even if they have been recently infected. Dr Jha said getting a booster now will not preclude Americans from getting another one in autumn, when variant-specific vaccines are likely to be available.

The daily number of reported cases in the United States has remained steady at around 100,000, according to a New York Times database - a figure that many experts say is under-reported because so many people are testing at home. But as of Monday, hospitalisations have risen 17 per cent over the past two weeks, according to federal data.

In the interview, Dr Jha said that figure could reflect those who are hospitalised for medical issues other than Covid-19 but who test positive; many Americans have underlying health conditions, and if they get infected with the coronavirus, they are at risk of developing more severe disease.

Dr Jha also suggested Americans test before attending large indoor gatherings or visiting a high-risk, immunocompromised person.

During Tuesday’s briefing, Dr Fauci said the increased hospitalisations – including an uptick in the number of Covid-19 patients who wind up in intensive care units – likely reflected a big rise in the number of unreported infections.

Nationwide as of Monday, the average number of people in intensive care units with the virus has increased by 21 per cent over the last two weeks, to more than 4,200, according to federal data.

Some other experts have said that the increase in hospitalisations indicates that a BA.5 surge is already underway.

"We're in a surge," said Dr Eric Topol, a cardiologist and director of the Scripps Research Translational Institute. Referring to the early days of the first omicron surge, he added: "It won't be as bad as what we went through in January. But it isn't good. And we basically have let down our guard."

In a recent post on online platform Substack, Dr Topol called BA.5 "the worst version of the virus that we've seen".

In recent weeks, there have been fewer than 400 coronavirus deaths reported each day, according to the Times' database, down from more than 2,600 a day at the height of the omicron surge.

If there were 300 deaths each day for a year, it would amount to more than 100,000 deaths - a figure That Dr Jha called "unacceptable".

By comparison, the CDC estimates that influenza claimed 12,000 to 52,000 lives in the US annually from 2010 to 2020.

A big issue for the administration is a lack of funds to purchase more vaccines and therapeutics. The FDA said last month that it had advised coronavirus vaccine manufacturers to update their booster formulations to target the two fast-spreading subvariants BA.4 and BA.5.

But Dr Jha said in the interview that the administration may not have enough doses for every American who wants one in autumn because Congress has refused to allocate any additional pandemic aid. In the event of a shortage, he said, the administration would prioritise older Americans and those with specific vulnerabilities.