COVID-19 and Reinfection: What Studies Revealed

Bako, John Chukwudi  April 2020

Distressing captions emerging across Asia reveals that patients in China, Japan, and South Korea who were previously diagnosed with COVID-19 and apparently recovered have been readmitted to the hospital after testing positive for the virus once more. There are 91 cases of people in South Korea being cleared of the virus and then getting it again. China and Japan have also reported it happening as well.

In Japan reports that a recovered coronavirus patient tested positive for a second time sparked up debate early March 2020 about the possibility. With some experts suggesting that recurrent infections may result from erroneous diagnoses linked to a limited testing capacity, but they also caution that there is possibility of the virus reactivating.

Reports from South Korea reveals that some coronavirus patients in South Korea are testing positive for the illness a second time. According to the country’s health officials. On Friday the Korea Centers for Disease Control and Prevention reported that 91 patients who had been cleared of COVID-19 and treatment and discharged from isolation are now testing positive again.

Health officials in the country said it is unclear how or why this has happened in the 91 patients, but an epidemiological investigation is underway. The officials said, “these people testing positive for the second time might not had been re-infected but could as well gotten the virus from their system”, officials said. Jeong Eun-kyeong, director of the Korea Centers for Disease Control and Prevention agrees that the virus may have “reactivated” in the patients rather than them becoming reinfected.

The director of Korea Center for Disease Control and Prevention stated that “While we are putting more weight on reactivation as the possible cause, we are conducting a comprehensive study on this.”  Recent events revealed that South Korea is witnessing another wave of COVID-19 cases. Reports released by NBC News shows that the country has documented a handful of local infection clusters in recent weeks as people resume moving about in places like Seoul.

Based on media reports “there have been similar reports out of China and Japan where patients who were diagnosed with COVID-19 and recovered have been readmitted to the hospital after testing positive.” Reasons for this development is still not too clear, this is because SARS-CoV-2, the novel coronavirus that causes COVID-19, was only discovered a few months ago, scientists are still trying to answer many big questions related to the virus and the disease it causes. Among them is whether patients can be re-infected by the virus after they seem to recover from the symptoms. According to report by Time, experts are of the view that it is likely the reports of patients who seemed to have recovered but then tested positive again were not examples of re-infection, but were cases where lingering infection was not detected by tests for a period of time.

Hitoshi Oshitani, a professor of virology at the Tohoku University Graduate School of Medicine, said coronavirus reinfections are possible but that they would likely be less severe. Marc Windisch, head of the Applied Molecular Virology Lab at the Institut Pasteur Korea, who made clear he was speaking in a personal capacity, agrees. He said that reinfections are usually either asymptomatic or accompanied by only mild symptoms because adaptive immune systems immediately take on the pathogen.

He said, however, that COVID-19 can be fatal in immunodeficient patients, transplant patients or those infected with HIV, “because the adaptive immune system is missing.”

Health officials in the country said it is unclear how or why this has happened in the 91 patients, but an epidemiological investigation is underway.

David Hui a respiratory medicine expert at the Chinese University of Hong Kong who also studied the 2002-2003 outbreak of severe acute respiratory syndrome (SARS), which is caused by a coronavirus in the same family as SARS-CoV-2 says that “It may be because of the quality of the specimen that they took and may be because the test was not so sensitive,”

Vineet Menachery, a virologist at the University of Texas Medical Branch, links it with antibodies which he said are normally produced in a patient’s body around seven to 10 days after the initial onset of a virus.

Menachery guesstimates that COVID-19 antibodies will stay in a patient’s system for “two to three years,” based on what’s known about other coronaviruses. He acknowledges the fact that since it is a novel virus therefore it is too early to know for certain to determine the true picture of the nature of COVID-19. He maintains in his submission that the degree of immunity could also differ from person to person depending on the strength of the patient’s antibody response. “Younger, healthier people will likely generate a more robust antibody response, giving them more protection against the virus in future.”

“We would expect that if you have antibodies that neutralize the virus, you will have immunity,” Menachery says. “How long the antibodies last is still in question.”

For Vineet Menachery, “a positive test after recovery could also be detecting the residual viral RNA that has remained in the body, but not in high enough amounts to cause disease”.  Menachery concludes by saying that “Viral RNA can last a long time even after the actual virus has been stopped.”

Meanwhile, one research carried out on recovered COVID-19 patients in the Southern Chinese city of Shenzhen found that 38 out of 262, or almost 15% of the patients, tested positive after they were discharged. The patients were confirmed through PCR (polymerase chain reaction) tests which at this time the gold specification for coronavirus testing.

Though the research is yet to be peer reviewed, but it offers some early insight into the potential for re-infection, experts say. The 38 patients were mainly young (below the age of 14) and displayed mild symptoms during their period of infection. The patients generally were not symptomatic at the time of their second positive test.

Furthermore, in Wuhan, China, where the pandemic began researchers looked at a case study of four medical workers who had three consecutive positive PCR tests after having seemingly recovered. Similar to the study in Shenzhen, the patients were asymptomatic and their family members were not infected, Time reports.

Issues around COVID-19 and immunity for previous sufferers is also not clearly established according to reports found online. This is due to limited time to research about the virus which rapidity of spread from human to human has not allowed and given space to determine whether patients who recover from COVID-19 are immune to the disease and how long the immunity of such patients will last.

Preliminary studies found online make available some hints to this. The study carried out by Chinese researchers and yet to be peer-reviewed found that antibodies in rhesus monkeys kept primates that had recovered from COVID-19 from becoming infected again upon exposure to the virus.