The latest data on U.S. COVID-19 test positivity rates shows a complicated picture as we head towards the new year.

COVID-19 has hit some countries far harder than others ... We want to know where infections are trending up or down relative to the size of the outbreak in each country. So in these charts ...

The map of flu activity across the United States continues to darken, both figuratively and literally, as case numbers spike ...

Bird flu cases are still rising in the U.S. as the virus continues to devastate poultry farms. More than 145 million chickens ...

The U.S. is seeing a "quad-demic" as cases of COVID-19, flu, RSV and norovirus spread at the same time. Experts said this is ...