The scientist in charge of the US push for a Covid-19 vaccine says there is “light at the end of the tunnel”.
Moncef Slaoui said he hoped the Food and Drug Administration (FDA) could give the go-ahead to a vaccine when it meets this week.
But for life to get back to normal by the spring, Americans still needed to follow safety measures, he added.
The US has seen record infections in recent days, with a daily death toll of more than 2,000.
The latest surge in cases is putting strain on hospitals, with large parts of the state of California set to enter new lockdown restrictions on Sunday.
States are also preparing to distribute a vaccine, with possible approval approaching. The FDA is meeting to discuss the UK-approved vaccine, made by Pfizer, on Thursday and will discuss approval of a second vaccine, made by Moderna, on 17 December.
Dr Slaoui heads up Operation Warp Speed, the US government’s programme to rapidly produce and delivery Covid-19 vaccines.
“Based on the data that I know, I expect the FDA to make a positive decision. But of course, it’s their decision,” he said.
“The first vaccine shipment will happen on the day after the vaccine is approved.”
The UK will begin its largest-ever vaccine rollout on Tuesday, after approving the Pfizer vaccine last week.
‘So much hope ahead’
Once FDA approval has been granted in the US, the vaccine is expected to be made available first to the country’s million healthcare workers and three million elderly people living in long-term care homes. It is up to states to decide which groups should be prioritised next.
“I think we may start to see some impact on the most susceptible people probably in the month of January and February,” Dr Slaoui told CBS.
“But on a population basis, for our lives to start getting back to normal, we’re talking about April or May.
“Therefore, it’s absolutely vital that everybody take comfort in the fact that we have light at the end of the tunnel, and find the energy in that to continue to wear our masks, distance, wash our hands… to make sure we’re there by the spring to benefit from the vaccine.”
His appeal came amid concern many Americans are still not following safety guidance, despite rising cases.
Speaking to NBC, Dr Deborah Birx, the White House coronavirus task force co-ordinator, criticised the Trump administration for flouting guidelines and peddling “myths” about the pandemic.
“I hear community members parroting back those situations, parroting back that masks don’t work, parroting back that we should work towards herd immunity,” Dr Birx said on Sunday.
“I want to be very frank to the American people. The vaccine is critical. But it’s not going to save us from the current surge,” she said.
“Only we can save us from this current surge.”
Nearly 14.6 million people have been infected with Covid-19 in the US, according to Johns Hopkins University, and 281,234 people have died – the highest figures of any country in the world.
It reported a record rise in cases for the third day in a row on Saturday, with 230,000 new infections in 24 hours.
As hospitals fill up, the southern region of California and its central valley and San Francisco will enter new lockdowns from Sunday night. Other areas could follow within days.
It is hoped the measures will slow the rapid spread of the virus before a vaccine can be widely administered.
US President-elect Joe Biden said last week he had not seen a detailed plan from the Trump administration to distribute vaccines to various states.
But speaking on CBS, Dr Slaoui pushed back on this. He said he was “looking forward” to meeting Mr Biden to discuss the rollout this week “because actually things have been really very appropriately planned”.