There is no evidence that people can be reinfected by the coronavirus after recovering from it the first time, according to a virologist who studies the body’s response to the disease.

This week a number of media outlets picked up on stories about people in South Korea and China who fully recovered from the virus testing positive for a second time.

South Korea’s Centres for Disease Control and Prevention (KCDC) said on Thursday that 141 people had tested positive again. A small number of similar cases have been reported in Wuhan, China, where the outbreak is thought to have begun.

If people were indeed being reinfected, governments around the world would be forced to rethink their strategies for beating the virus. Many countries are seeking what is known as “herd immunity” — where a community is protected by a large percentage of the population contracting and then becoming immune to the virus.

But Dr Angela Rasmussen, a virologist and an associate research scientist at the Columbia University Mailman School of Public Health, told The Independent that people were misinterpreting the reports about reinfections.

“The test that is used only detects viral RNA (Ribonucleic acid) — the genetic material of the virus. It doesn’t necessarily correlate to the amount of infectious virus that could be transmitted to anyone. We know that often many viral infections can continue to produce detectable RNA long after a patient has recovered without actually being contagious,” she said.

In other words, a person might carry remnants of the virus after recovery, but without it being infectious or of danger to the host or others.

Dr Rasmusseun studies the body's response to emerging viral infections like Ebola and Covid-19, and how that contributes to disease severity.

“We haven’t seen any data to suggest these people have a truly ‘reactivated’ infection or a repeat infection, that they are contagious, or that they are even sick. These reports were not accompanied by any hard data to support them,” she added.

South Korean health officials have said it remains unclear what is behind the trend, with epidemiological investigations still under way. Jeong Eun-kyeong, director of the KCDC, said the virus may have been “reactivated” rather than the patients being re-infected.

Some experts have also speculated that false test results could also be behind the apparent reactivations.

Research teams around the world are studying the novel coronavirus in order to help public officials make decisions about how best to fight it. But despite their best efforts, there is still much we don’t know about the deadly virus. Scientists still do not know the strength of immunity to the coronavirus in a recovered patient, or how long it lasts.

A major study launched last week is looking into the effectiveness of using blood plasma from Covid-19 convalescents to trigger immunity to the virus.

Rather than test whether the subject currently has the virus, these tests will determine if a person has had it and subsequently recovered – even if they haven’t displayed symptoms. They do that by testing the blood for antibodies associated with the disease. A person with the antibodies in their blood would theoretically be immune to the virus.

“The level and the duration of protective immunity is not something that these tests tell us. They tell us that you’ve been infected, and there are antibodies, but whether they’re neutralising and entirely protective, we frankly just don’t know yet,” said Dr Elitza Theel, director of the Mayo Clinic laboratory performing antibody testing for Covid-19.

“But I think what we can say is that these individuals are likely at lower risk of getting infected compared to antibody-negative individuals,” she added.

Dr Theel went on to say that this research could be used as a “tool to help more strategically redeploy individuals back to work.”