LONDON (Reuters) - Britain has detected 77 cases of the South African variant of COVID-19, the health minister said on Sunday, also urging people to strictly follow lockdown rules as the best precaution against Britain’s own potentially more deadly variant. Matt Hancock said all 77 cases were connected to travel from South Africa and were under close observation, as were nine identified cases of a Brazilian variant. “They are under very close observation, and we have enhanced contact tracing to do everything we possibly can to stop them from spreading,” he said during an interview on BBC television. Oxford professor Anthony Harnden, deputy chair of a scientific committee on vaccination that advises the government, said the South African and Brazilian variants were of concern because COVID-19 vaccines may not be effective against them. “The new variants abroad are a real worry. The South African and the Brazilian Amazonian ones, there are hints that there will be vaccine escape,” he said on Sky News, adding that new variants would keep appearing around the world. Britain has the highest death toll in Europe from COVID-19, at close to 100,000, and has been in lockdown for most of January with hospitals struggling to cope with record numbers of seriously ill COVID patients. The government has attributed the high transmission rates that led it to impose the lockdown in part to a highly contagious variant first identified in southeast England and now prevalent in many areas. Prime Minister Boris Johnson said on Friday the English variant may be associated with a higher level of mortality, although scientists have said the evidence on that remained uncertain, a message Hancock re-emphasised on Sunday. “The scientists do think that it may be more deadly, and they’ve put various estimates on that from about 10% more deadly to a bit more than that, we are not exactly certain about how much more deadly,” he said on Sky News. “In a way, for all of us, that doesn’t matter, what matters is we have got to get this virus under control and the only way you do that is by stopping the social contact and following the rules,” he said.