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Coronavirus patients should have “some level of protection” after they recover from the illness — but it’s unclear how long that immunity lasts, the World Health Organization said Monday.

Dr. Maria Van Kerkhove, the WHO’s technical lead on COVID-19, said there are a number of studies underway about what the presence of antibodies means in terms of immunity for recovered patients.

“We expect people who have been infected with COVID-19 to develop a response that has some level of protection,” Van Kerkhove told reporters. “What we don’t know is how strong that protection is, and if that is seen in everyone that is infected and how long that lasts.”

“Right now, we are not able to say that someone who has antibodies is immune,” she added, citing a lack of research.

The agency warned Saturday that there’s no evidence that recovered patients won’t catch the virus again.

“Some governments have suggested that the detection of antibodies … could serve as the basis for an ‘immunity passport’ or ‘risk-free certificate,’” the WHO said.

“There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.”