United Airlines has made this announcement:

California currently has more than 18,309 confirmed coronavirus cases and 507 fatalities in the state to-date. Bringing medical volunteers to the state will help bring much needed support to California’s medical professionals and the more than 2,825 individuals hospitalized, including the 1,132 people in intensive care.
“Our frontline healthcare workers are heroes. We are profoundly grateful to them for their unwavering commitment to support our communities and medical providers at this time of exceptional need,” said Janet Lamkin, President, California for United Airlines. “It is our hope that providing air travel at no cost will allow additional courageous volunteers and first responders the ability to reach health care facilities throughout California, which continues to feel the impact of the COVID-19 pandemic.”
United is working with the state of California to ensure qualified medical professionals are staffed in hospitals best suited to their areas of expertise and have the proper housing and transportation to enable them to effectively offer their services.
United remains committed to offering as many flights as possible to connect much-needed medical professionals to the frontlines in California, with 50 daily flights into SFO and 13 daily flights at LAX. The airline plans to expand this program to critical areas within the coming days and weeks to allow more volunteers to offer their vitally important services in the places that need them most.
Those interested in volunteering or learning more about the program can visit the California State website here.
In other news, United is operating medical supplies charter flights:

The second shipment came into San Francisco the following day containing surgical gowns, hazmat suits and several million more masks for first responders in California. United employees unloaded that aircraft upon arrival and helped get the PPE onto trucks for delivery to Bay Area hospitals.

We are operating, on average, 20 cargo-only flights each day between six U.S. hubs and cities in Asia, Australia, Europe and the Middle East. In the process of doing so, we are moving thousands of pounds of medical supplies, pharmaceuticals and PPE, in addition to those mentioned above, to help stem the spread of COVID-19 and treat those afflicted.
United Airlines aircraft photo gallery (Boeing, new livery):

