Excess weight, which is often linked to metabolic abnormalities, can contribute to a wide variety of health problems.

HIV treatment usually requires daily pills, but longer-acting regimens are gaining ground.

The CDC recommends that everyone ages 13 to 64 get a routine HIV test at least once.

Mutations can affect how viruses behave and how well drugs and vaccines work.

Hepatitis A and E usually resolve on their own, but hepatitis B and C can cause serious liver disease, including cirrhosis and liver cancer.

Long-lived memory immune cells continue to provide protection even after antibody levels drop.

New guidelines recommend focusing on healthy foods but don’t restrict added sugars or alcohol as much as some experts had hoped.

Disruptions in prevention and care could threaten progress toward ending the HIV epidemic.

Vaccine development is proceeding at an unprecedented pace, but could still hit snags on the way to approval.

Try to do at least 150 minutes of moderate-intensity physical activity every week.