South Korea’s third wave of Covid-19 continued on Saturday after medical groups called for stricter social-distancing curbs and the government warned of tougher measures if infections are not quickly contained. The Korea Disease Control and Prevention Agency reported 386 new daily coronavirus cases as of Friday midnight, bringing total infections to 30,403, with 503 deaths. New cases topped 300 for the fourth day in a row, after Tuesday saw the highest since August. Without effective measures such as stricter distancing, the daily tally could reach 1,000 in the next two weeks, the Korean Society of Infectious Diseases and eight other medical societies warned. “This winter is expected to be the biggest challenge in the Covid-19 response,” the groups said in a statement on Friday, calling on the public to take steps voluntarily. “There has been good news on successful development of Covid-19 vaccines, but this winter we have to stop it without a vaccine.” Although South Korea tightened prevention guidelines on Thursday and Prime Minister Chung Sye-kyun called on Friday for all social gatherings to be cancelled, bars, nightclubs, religious services and sports events are still allowed with attendance restrictions.