The page does not contain content images that need explanations. Adequate short alternate texts can be written for all images.
It is a rather common mistake to treat logos as content images. Someone might think that the WHO symbol in the upper left corner is essentially graphic, and it indeed is. Yet, there is normally no need to explain it to a person who does not see it. You might write an explanation of it for people who do see it, but this is hardly an accessibility issue. Such an explanation would best be included into a page that specifically discusses the WHO symbol (e.g., its origin, proper use, etc.).