Berlin, June 11 : Germany's seven-day Covid-19 incidence rate has risen to 319 infections per 100,000 people due to the spread of the more contagious Omicron variants BA.4 and BA.5, the Robert Koch Institute (RKI) for infectious diseases said. The shares of the two subvariants BA.5 and BA.4 have doubled within one week to 10 per cent and 2.1 per cent, respectively, according to the RKI's latest weekly report released on Friday. The spike driven by the latest subvariants could also lead to an "overall increase in infection numbers and renewed infection pressure on vulnerable groups as early as summer," the RKI warned. Available data on BA.4 and BA.5, however, did not point towards a more severe disease progression or more deaths than those registered with previous Omicron subvariants, according to the authority. "We are not experiencing an infection-free summer this year, but that is not threatening for now," said Berlin Charite virologist, Christian Drosten. The German government's Covid-19 expert council on Wednesday warned that there would be a renewed significant strain on the country's healthcare system in autumn and winter. The council is to present its analysis on the efficiency of the coronavirus measures at the end of June, Xinhua news agency reported. Health Minister Karl Lauterbach said he wanted to wait for the report before considering a tightening of the measures again. The Infection Protection Act, which is expiring at the end of September, "must definitely be changed again and must also be extended above all else," he stressed. At present, only the so-called basic protection measures still apply in Germany. The wearing of face masks is only mandatory on public transport, in airplanes and healthcare institutions, such as hospitals and care facilities. /IANS