WASHINGTON — The Trump administration tied billions of dollars in badly needed coronavirus medical funding this spring to hospitals’ cooperation with a private vendor collecting data for a new Covid-19 database that bypassed the Centers for Disease Control and Prevention.

The highly unusual demand, aimed at hospitals in coronavirus hot spots using funds passed by Congress with no preconditions, alarmed some hospital administrators and even some federal health officials.

Researchers in Hong Kong are reporting the first confirmed case of reinfection with the coronavirus.

“An apparently young and healthy patient had a second case of Covid-19 infection which was diagnosed 4.5 months after the first episode,” University of Hong Kong researchers said Monday in a statement.

The report is of concern because it suggests that immunity to the coronavirus may last only a few months in some people. And it has implications for vaccines being developed for the virus.