GENEVA -- The World Health Organization's emergencies chief says it's "premature" and "unrealistic" to think that the pandemic might be stopped by the end of the year.

But Dr. Michael Ryan said Monday that the recent arrival of effective vaccines could dramatically reduce hospitalizations and death.

Ryan said that the world's focus right now should be to keep transmission of COVID-19 as low as possible.

WHO director Tedros Adhanom Ghebreyesus said it was "regrettable" that younger and healthier people in rich countries are being vaccinated before at-risk health workers in the developing world.

He warned against complacency, noting a recent increase in cases.