Bill Gates says he has COVID-19

Microsoft co-founder Bill Gates said Tuesday he has tested positive for COVID-19 and is experiencing mild symptoms. Via Twitter, the billionaire philanthropist said he will isolate until he is again healthy.

"I'm fortunate to be vaccinated and boosted and have access to testing and great medical care," Gates wrote.

The Bill and Melinda Gates Foundation focuses on public health and has committed more than $350 million for the development of vaccines, diagnostics and therapeutics in the fight against the coronavirus. The Seattle-based foundation is among the most influential private foundations in the world, with an endowment of about $65 billion.

Bill Gates has been a vocal proponent for ways to curb the pandemic, including widening access to vaccines and medication for poorer countries. The Gates Foundation in October said it would spend $120 million to boost access to generic versions of drugmaker Merck's antiviral COVID-19 pill for lower-income countries.

In the U.S., COVID-19 cases are on the rise in more than 40 states, according to data from the Centers for Disease Control and Prevention.