Britain may have already achieved a sufficient level of herd immunity to prevent a second wave of Covid-19, an Oxford University study has suggested. Scientists believe the “threshold” may have been lowered because many people may already be immune to the disease without ever having caught it. According to a model produced by the Oxford team, as few as 20 per cent of the population may need to be resistant to the virus in order to prevent a new epidemic spreading. As Bill Gardner reports, experts suggest a sizeable number of people may have immunity because of Covid-19’s similarity to the common cold. Meanwhile, Boris Johnson will announce an additional £3bn to keep Nightingale hospitals open until next March amid fears of a resurgence of Covid-19 this winter.