Here's what to do if you're feeling sick or have come in to close or casual contact with a coronavirus case.

Coronavirus: what to do if you've been exposed

A Japanese man who was initially infected with coronavirus and recovered has since tested positive a second time for the deadly disease.

The man, in his seventies, first tested positive for the illness on February 14 as a passenger on-board the then-quarantined Diamond Princess cruise ship.

He underwent further isolation and was subsequently treated at a medical facility in Tokyo, reports Japanese news agency NHK.

After he was given a clean bill of health on March 2, he returned to his home in the Mie Prefecture, where he started exhibiting symptoms again, including a fever of 39 degrees Celsius.

He went back to the hospital on Thursday for testing and by Saturday it was confirmed he was infected with COVID-19 a second time.

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NHK reports the man is currently undergoing treatment and those he came into contact with are also being tested.

As the world goes into lockdown as a way to contain the spread of disease, health officials are now facing the possibility coronavirus may strike a second time.

A woman in Japan also recently tested positive for COVID-19 first being diagnosed with coronavirus in late January according to a statement released by Osaka’s prefectural government, was discharged shortly after her symptoms had improved.

A subsequent test came back negative for the virus – but three weeks later, she returned to hospital with a sore throat and chest pain, and tested positive for the disease again.

Similar cases of “reinfection” have been reported in China, where a physician warned it was possible for recovered patients to contract the virus again.

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Speaking at a Chinese National Health Commission briefing on January 30, director of pneumonia prevention and treatment at the China-Japan Friendship Hospital in Beijing, Zhan Quingyuan, said that while COVID-19 patients all seem to generate antibodies against the coronavirus, in some individuals the antibodies don’t appear to last for very long.

While scientists continue to understand more comprehensively how the disease works, at this stage there wasn’t a definitive position on whether the illness returning a second time was a given.

Speaking to news.com.au previously, senior medical virologist with NSW Health Pathology, Professor William Rawlinson said while this may be a feature of the virus, it was too soon to say.

There are several possible scenarios as to why people may become infected a second time, including that detection of the virus becomes negative in the nose and throat but persists in the lungs.

“Once you have the infection, it could remain dormant and with minimal symptoms, and then you can get an exacerbation if it finds its way into the lungs,” professor at the NYU School of Medicine, Philip Tierno, told Reuters.

However, international health expert at the University of Pittsburgh Donald Burke told Wired that scientists were a long way from finding any “solid” evidence that suggests people could be reinfected.