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No proof of Covid-19 reinfection, yet

Going back to get a second round of Covid-19 results is scary, but testing positive again is even worse. This is the account of three patients who have tested positive for Covid-19 more than once. 

A clinician who did not want to be named said that in April she had a bout of diarrhoea and informed her boss. “Our protocols are to report it to our manager if we feel any of the symptoms. I didn’t have any of the other symptoms, but couldn’t place why I had diarrhoea. I was told to take a test and a day or so later, it was positive.”

She recovered and went back to work. Just two weeks ago, she felt her body starting to ache, as well as the onset of fever symptoms. She called her manager, who advised her to test again. 

The test came back positive. 

“I was so scared — I didn’t know what to do. The symptoms have not been bad, just a few days of body aches and flu-like symptoms, but getting the virus again has been a shock because at work we have enough PPE [personal protective equipment] to deal with Covid-19. I don’t know how I could have been reinfected,” she said.

But experts say although there have been several anecdotal reports of reinfection with the virus, there is no definitive evidence that this is the case. 

According to top epidemiologist and infectious diseases specialist Professor Salim Abdool Karim, it seems that most people who get the virus develop antibodies. But for those who have mild symptoms or are asymptomatic, it appears that the antibodies disappear very quickly — in about three months. 

“But we don’t know whether the antibodies will prevent a new infection from occurring. In a small proportion of patients, they do not clear the virus completely; instead, they have long-term shedding. The virus in these cases is present and infectious. Though a person can test positive, we cannot grow the virus. It is not live,” Karim said.

In explaining these complexities, he said some individuals remain positive for months. This was first found in China and then in South Korea, where there were about 150 cases in which patients had the infection, tested positive and then recovered, becoming negative. A few weeks later, they became positive again. 

“Initially the reports said that these people are getting the second infection. After an investigation, it turns out that this was not a second infection. This has been described all over the world. In every case investigated, it has shown that it is still the first virus. We do not have proof that anyone has been reinfected,” said Karim, the chairperson of the nation’s Covid-19 ministerial advisory committee.

Meanwhile, another patient, who asked not to be named, said he had a similar experience. 

“Right at the beginning of the pandemic, we tested positive after my wife had undergone random testing at work. My wife tested positive, and so did I. I had a headache, cough and pain in the abdominal [area]. We isolated, and after 14 days, we tested negative and [were] cleared to go back to work,” said the patient.

But about a month ago, the patient began feeling fatigued, and a day later, he started experiencing flu-like symptoms. “The doctor I visited told me that there is a flu bug doing the rounds. I said it must Covid-19, but the doctor told me there was no way I could get it again. So he didn’t do a second test and instead prescribed me flu medication. He said if [they] tested me, [they] would be wasting my time,” he said.

But the patient’s partner developed a headache and stomach ache. His partner went to another doctor who did test her again, and the results came back positive. He was then also tested, and the results were positive.

According to the patient, the symptoms were quite vicious this second time around. 

“Doctors were baffled and wanted to monitor us during the quarantine period to figure out how we could have tested positive for the virus, then negative and weeks later test positive again. It has been quite a harrowing time.”

Experts that the Mail & Guardian spoke to would not comment on specific cases, saying that each should be referred for further research to ascertain if the gene sequence of the second test was the same as the first. This is one of the ways to prove that reinfection has occurred. 

Professor Cheryl Cohen from the National Institute for Communicable Diseases (NICD)said the centre had received several reports of possible reinfection from more than one province.

The centre investigates these cases by collecting information on the patient and their underlying risk conditions, symptoms of each possible infection episode, and the PCR (polymerase chain reaction) evidence of the first and subsequent infections, as well of any proof of negative test results in the intervening period,if available. 

“If possible, we will obtain the virus strains from the initial and subsequent infections, which could allow us to sequence the virus to see if it is the same strain or a different strain,” she said.

NICD department head Professor Adrian Puren said the understanding of the immune response to Covid-19 infection is incomplete. 

Puren explained that the current advice is that people infected with common viruses related to Covid-19 appear to become susceptible to reinfection about 90 days after the initial infection. This means that a positive PCR test conducted during the 90 days after the illness more likely represents persistent shedding of the virus’s genes rather than reinfection. 

The Covid-19 patients that the M&G interviewed all tested positive again in those 90 days. 

“If a person becomes symptomatic during 90 days post-infection and fails to identify a diagnosis other than SARS-CoV-2 infection … then the person may require an investigation for SARS-CoV-2 reinfection. This should be done in consultation with an infectious-disease or infection-control expert,” Puren said.

Though there is no concrete evidence that reinfection has occurred in South Africa , experts warn that people should still follow the same hygiene protocols, of handwashing, physical distancing and wearing a mask, whether reinfection is possible or not.

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