Evidence shows most people who recover from Covid-19 do produce antibodies, one of the government's most senior medics said today.
Meanwhile the health secretary said he would "not yet" feel comfortable being in a crowded room despite already having had the virus.
Matt Hancock tested positive for coronavirus in late March, spending two weeks in self-isolation before recovering and returning to work.
At today's Downing Street press conference, he and deputy chief medical officer Professor Jonathan Van-Tam were asked about the evidence on whether people could catch the disease twice.