COVID-19 cases are rising in half of U.S. states. What to know about COVID trends and the new Stratus and Nimbus variants.

COVID-19 cases in California show a potential summer surge, with wastewater data indicating increased virus levels.

According to a Johns Hopkins report, several virological, behavioural, and environmental factors drive summer Covid-19 waves.

'The summer surge is real': President Biden has COVID, as experts say cases are on the rise across the US, including in Pa.