Hong Kong is home to the first confirmed case of a patient being infected for a second time with the novel coronavirus. 

University of Hong Kong researchers released a statement Monday saying the first confirmed case of reinfection was found in a 33-year-old who was first infected with COVID-19 between 4-5 months ago. 

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

Minnesota Health Commissioner Jan Malcolm said "we are aware of that case report," while infectious disease director Kris Ehresmann said reinfection is a possibility that "we have been waiting for." 

The Hong Kong patient, who had mild symptoms the first time and no symptoms the second time, is believed to have contracted the virus again while traveling in Spain. 

“Our results prove that his second infection is caused by a new virus that he acquired recently rather than prolonged viral shedding,” said Dr. Kelvin Kai-Wang To, a clinical microbiologist at the University of Hong Kong.

There are no known instances of reinfection in Minnesota, though health officials from La Crosse County in southwest Wisconsin announced a suspected case of reinfection in early August. The county health department said it was treating the case as a reinfection, mainly because the patient's symptoms "were not the same the second time." 

Other instances of secondary positive tests are believed to be caused by virus remnants remaining in a person's system, which can be detected by diagnostic tests months later. The CDC advises individuals experiencing COVID-19 symptoms for a second time more than three months after the original instance should be re-tested. 

Ehresmann said hearing news of a confirmed reinfection case is a "disappointment," but "all the more reason why it's so important that everyone needs to continue to socially distance, wear a mask, and stay home if you're sick." 

The CDC says the level of immunity a person has after contracting COVID-19 is unknown and being studied.