Rates of new Covid-19 cases topped 50,000 a day last week, leading scientists and health experts to warn that the country could be forced into a lockdown later this year as rising numbers of infections look likely to continue until autumn. In these circumstances, they said, wearing of masks should be continued despite the government’s refusal to make such a move official. “If you don’t wear masks, the virus will spread further. It is as simple as that,” said Julian Tang, a clinical virologist at Leicester University. Tang said masks clearly limit the spread of viral particles from an infected person and also cut a wearer’s chance of picking up an infection from someone else. “Masks work both ways,” he told the Observer.