The World Health Organization warned on Wednesday that COVID-19, the illness caused by the novel coronavirus, is spreading at a worrying pace in some parts of the northern hemisphere, a few months away from the winter influenza season.

WHO technical lead for COVID-19, Maria Van Kerkhove, said they are seeing an increase in hospitalizations, in intensive care units in several places including Spain, France, Montenegro, Ukraine and some states of the United States. She said it was worrying “because we’re in mid-September and we haven’t started the flu season yet.”

Van Kerkhove also said hospitalizations of people aged 15-44 infected with COVID-19 were increasing in several countries. Dr. Mike Ryan, the WHO’s top emergency expert, advised people at high risk for COVID-19 infections to get a flu vaccination.

US President Donald Trump said on Wednesday at least 100 million doses of a coronavirus vaccine could be distributed in the United States by the end of 2020, months earlier than a top government health official predicted earlier in the day.

Earlier on Wednesday, Robert Redfield, director of the federal Centers for Disease Control and Prevention, said a COVID-19 vaccine could be broadly rolled out by the middle of next year or a little later.