One in four deaths can be attributed to preventable environmental causes, according to statistics read at a meeting kicking off New York Climate Week.
The WHO chief's comments come as health authorities and pharmaceutical companies across the world have been racing to update vaccines to combat newer emerging coronavirus variants.
Moderna said it had shared the new finding on its vaccine with regulators and submitted it for peer review publication.
Since 2005, there have been 37 cases of swine flu in the US, WHO said, and 512 globally.
British scientists are working on a vaccine against Disease X, the hypothetical pathogen that will cause the next pandemic.
Cases of MERS-CoV - which can cause fever, coughing and shortness of breath, and in some cases can lead to pneumonia - have been recorded in 27 countries since 2012, according to WHO figures.
Some of the most popular European cities have surprisingly poor air quality.
JPOST Digital Library
