Man in Hong Kong has become the first confirmed patient to be infected with the coronavirus for second time, according to researchers at the University of Hong Kong.

The finding suggests that some patients who recover from COVID-19, the disease caused by the coronavirus, may have only short-lived immunity from reinfection. The case will likely also be significant for scientists who have been working on treatments using antibodies from recovered coronavirus patients, and those who have been scrambling to develop a safe and effective vaccine, though it’s too soon to draw any firm conclusions.