An approved coronavirus vaccine may only end up being effective 50% of the time, the top US infectious diseases expert has warned.
The chances of a COVID-19 vaccine being almost 100% effective are “not great”, Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases said on Friday.
“We don’t know yet what the efficacy might be. We don’t know if it will be 50% or 60%. I’d like it to be 75% or more,” he told a Brown University webinar.
Dr Fauci warned that the “public health approach must never be abandoned”, as it may prove near impossible to develop a vaccine that is as high as 98% effective.
This means Americans should maintain social distancing and wear face coverings in enclosed spaces or large crowds to stop the spread of the virus.
On Friday, the US drugs regulator revealed independent experts would have to review any vaccine before it is approved.
The Food and Drug Administration (FDA) said it would organise an outside advisory committee before giving the green light, in an apparent bid to reassure people it will not cut corners in the race to offer immunity.
Dr Fauci also urged states to react as quickly as possible to increases of just 1% or 2% in coronavirus cases.
It comes after the US death toll surpassed 160,000 with 4.91 million cases reported nationwide.
The US accounts for nearly a quarter of the world’s virus deaths, in front of Brazil, Mexico and the UK, which have the next highest numbers of fatalities.
States are currently considering whether schools should reopen in the coming weeks.
Several – including California, Texas and Florida – have had to go back into lockdown after large spikes in cases.
Democratic presidential candidate Joe Biden was forced to accept his Wisconsin nomination virtually in the latest virus setback to the November election.