One major reason why it has been difficult to develop an effective HIV vaccine is that the virus mutates very rapidly, ...

XEC is also an offshoot of omicron, the widely spread variant that formed in 2021. According to experts, it has some of omicron’s features, too — like less severe symptoms and easy transmissibility.

Health data show that COVID-19 still surpasses all other infectious respiratory illnesses as a cause of severe illness, ...

Catching the virus that causes COVID-19 or getting a COVID-19 vaccination gives you protection, also called immunity, from the virus. But over time, that protection seems to ...