TOKYO (Reuters) - A freezing northern city that has become a red flag for Japan’s winter vulnerability to the coronavirus pandemic is weathering the worst of its COVID-19 crisis, local medical officials say, as military nurses take the strain from drained hospital staff. Asahikawa city was hit by outbreaks at two major hospitals, exacerbated by sub-zero temperatures and restricted ventilation that can promote the virus’ spread. But a voluntary lockdown, combined with medical reinforcements sent by central government last week, have helped the city stabilise - for now. There are now signs the cluster crisis is “peaking out”, said Yasutaka Kakinoki, a hematologist at Asahikawa City Hospital. That’s a relief, he told Reuters by phone, as staff have been pushed to the brink fighting the steady rise in COVID-19 cases over the last two months. “The lack of healthcare workers is a big problem,” he said. Although Japan hasn’t seen massive outbreaks like in the United States and Europe, infections on Saturday hit a new daily record as winter sets in. Though its winter is much more extreme than most cities in Japan, Asahikawa has shown how cold weather can ramp up infections - and the interventions that may be needed if Japan is to continue to largely weather the crisis. Asahikawa, a city of 340,000, has so far accounted for 821 cases and 65 deaths, or 20%, of the northern island of Hokkaido’s 330 fatalities. That equates to a case fatality rate of about 8% for the city, compared to about 1% for Japan’s 182,305 cases so far. Urging residents to stay home last week, the mayor, Masahito Nishikawa, said there were concerns there weren’t enough medical staff available to respond to new infections, or accidents and illnesses. Clusters of COVID-19 sprang up at Asahi Kosei Hospital and Yoshida Hospital early last month and spread rapidly in the hospitals. Asahi Kosei president posted an online plea for staffing help on Dec. 1, which ultimately prompted the central government to eventually dispatch nurses from Japan’s Self-Defense Forces. The president of Yoshida Hospital has publicly credited the military nurses for turning the tide there. COLD WAVE Hokkaido was the first prefecture in Japan to declare a state of emergency earlier this year during the initial wave of the pandemic, which has claimed 2,662 lives in the country amid 183,017 cases so far this year. Researchers had warned that airborne transmission of the virus increases when people spend more time in closed rooms breathing dry air - hard to avoid in Hokkaido, an island whose snowbound winter makes it a popular destination for ski enthusiasts. Asahikawa holds the record for Japan’s lowest recorded temperature, -41C (-41.8F) hit in 1902. A campaign to promote domestic tourism across the country met with criticism in Japan as the numbers of infections rose nationwide. Although Hokkaido was excluded from the campaign after its clusters broke out, the programme continued in much of the rest of the country. Backed by Prime Minister Yoshihide Suga, the ‘Go To’ promotion offered cut-price travel in a bid to bolster local economies suffering from the absence of foreign visitors amid the pandemic. “It’s common sense that people moving around is going to have an effect on spreading infection,” said Michiyuki Matsuzaki, a physician running the Asahikawa Northern Clinic. “The prime minister should rethink this policy.” Suga had held out on suspending the campaign, even as criticism mounted and his support fell in polls. But on Monday he announced a temporary halt in the programme until early January. Even before the soft lockdown, Asahikawa’s streets resembled a “ghost town,” said Masayuki Yoshio, who runs three restaurants in the city’s centre. As business dropped off, he and his staff focused on making and sending dozens of packed lunches to hospital staff hit by the contagion. Yoshio said he was concerned about the impact on shops and workers, but said the slowdown may be necessary to prevent further catastrophe. “All the business owners are under pressure,” he said. “If what happened in Asahikawa breaks out all over Japan, it would be a devastating situation.”