Just as immunization has been postponed in some countries, heath-care services for other diseases, such as malaria, have been disrupted, Tedros said, noting that the number of malaria cases in sub-Saharan Africa could double.

At least 21 countries are reporting vaccine shortages as a result of travel restrictions meant to curb the spread of the Covid-19 pandemic, WHO Director-General Tedros Adhanom Ghebreyesus said during a press conference at the agency's Geneva headquarters. "The tragic reality is children will die as a result."

The World Health Organization warned Monday that children across the world will die as the coronavirus pandemic forces some countries to temporarily halt vaccinations for other deadly diseases such as polio.

Tedros urged member countries to help ensure vaccination programs are fully funded, saying the Global Alliance for Vaccines and Immunization will need $7.4 billion to immunize 300 million children with 18 vaccines by 2025.

"When vaccination coverage goes down, more outbreaks will occur," Tedros said.

The coronavirus outbreak, which began in Wuhan, China, in late December, is "far from over," Tedros said, adding the agency is concerned about new cases cropping up in Africa, eastern Europe, Latin America and some Asian countries.

"We are continuing to support these countries with technical assistance through our regional and country offices and with supplies through solidarity flights," he said.

WHO warned world leaders last week that they will need to manage around the coronavirus for the foreseeable future as cases level off or decline in some countries, while peaking in others and resurging in areas where the Covid-19 pandemic appeared to be under control.

"Make no mistake, we have a long way to go. This virus will be with us for a long time," Tedros said Wednesday.

While social distancing measures put in place in numerous countries to slow the spread of the coronavirus have been successful, the virus remains "extremely dangerous," Tedros said at the time. Current data show "most of the world's population remains susceptible," he said, meaning outbreaks can easily "reignite."