ZURICH (Reuters) – It is unclear how the arrival of winter in the southern hemisphere will impact the novel coronavirus, the head of the World Health Organization’s emergencies programme Mike Ryan said on Wednesday.

“We don’t know how the coronavirus is going to be,” Ryan said during a virtual press conference. “Right now, we have no data to suggest that the virus will behave more aggressively or transmit more efficiently or not,” Ryan said, adding that the impact of summer’s arrival in the northern hemisphere was also unclear.

“We cannot rely on an expectation that the season or the temperature will be the answer to (the disease’s spread),” he said.