Immunity to COVID-19 in Sweden is likely lower than previously estimated, the country's top epidemiologist and architect of its unorthodox pandemic strategy said on Thursday, as daily deaths in the disease rose to their highest level in months. Chief Epidemiologist Anders Tegnell, whose rejection of lockdowns and widespread use of face masks made Sweden a European outlier, also acknowledged the country was battling a second wave of the pandemic after suggesting in August such a scenario was unlikely. Sweden registered 4,658 new coronavirus cases on Thursday, just below a daily record set last week, Health Agency data showed, in a resurgence of the virus that has seen hospitalisations and intensive care admissions mount.