At the moment, a lot of people in the US opt to get a covid vaccination around the time they get their annual flu jab. Each year, a flu vaccine is developed to protect against what scientists predict will be the dominant strain of virus circulating come flu season, which tends to run from October through March.

But that was before this nation was deep in the throes of its second-largest measles outbreak — more than 1,000 confirmed cases this year — since the disease was declared eliminated in 2000. At least three people have died, including two children.