With official warnings of a potential "twindemic" as COVID-19 surges in Europe just ahead of the flu season, the WHO is recommending that people get a seasonal flu vaccine to prevent hospitals being overwhelmed.
But some countries appear not to have enough for everyone, it said.
Ann Moen, WHO chief of influenza preparedness and response, told a U.N. briefing in Geneva that some countries are having trouble sourcing additional vaccine, although she declined to name any.
In the event of shortfalls, countries should prioritize five groups and especially health care workers and the elderly, the WHO recommends.
Most countries place their orders about 9-12 months in advance based on national health policies so have already decided on their doses for this year's flu season.