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People can contract COVID-19 twice and suffer two completely separate episodes of the disease in just four months, doctors have said.
The warning comes after evidence emerged from a man whose infections were four months apart with no symptoms and serial negative tests for the virus.
But although the decrease in immunity could increase the risk of contracting coronavirus Again, doctors say that a first serious infection may be followed by milder symptoms the second time.
While people who are being reinfected COVID-19 It is not unheard of, very few cases have been reported.
Previous studies have indicated that reinfection is possible, but have tended to suggest that people generally gain some immunity for more than four months.
And experts who highlighted the case in the journal BMJ Case Reports say it remains unclear so far whether this actually represents continued viral shedding from the initial virus attack rather than genuine reinfection.
The authors of the peer-reviewed study say: “As the COVID-19 The pandemic has evolved, emerging reports have shown that reinfection of SARS-CoV-2 is possible, so that testing positive for SARS-CoV-2 RNA over a long period of time does not necessarily indicate persistent viral shedding of a previous COVID-19 infection “.
They add: “If patients with severe disease develop more robust antibody levels, the duration of protection against reinfection and the resulting severity of the disease, if it occurs, may be silenced. Future observations would certainly shed more light on this if this hypothesis holds true.
“The role of the presence or absence of antibodies after initial infection in survivors of a first COVID-19 episode and its role in mitigating the risk of reinfection by SARS-CoV-2 is not clearly defined. However, it is plausible that decreased immunity or the absence of antibodies after the first episode of SARS CoV-2 infection may make one more susceptible to reinfection. “
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COVID-19 antibodies last ‘at least 6 months’
The case highlighted by the authors involves a man in his 40s who was admitted to hospital with a mild COVID-19 infection four months after an initial attack of severe illness in April 2020.
He had well-controlled type 2 diabetes, an underactive thyroid gland, and was obese – known risk factors for severe COVID-19 infection.
When he was first infected, he was admitted to the hospital with breathing difficulties and a high-pitched hiss caused by the interruption of air flow, known as stridor.
He developed respiratory failure and required mechanical ventilation and blood thinners along with various other medications used to treat COVID-19.
During a two-month stay in the hospital, he developed a series of serious complications before being stabilized and discharged to an intensive care center for rehabilitation.
In the second instance, in August 2020, he tested positive for coronavirus, after four negative tests during the previous three months, and he remained in the hospital for only one day.
He was then admitted back to the hospital two weeks later and remained admitted for another week.
The man insisted that he had had very little exposure to other people, except for relatives and his immediate family who had no symptoms and had not been ill recently.
The authors suggested that positive test results several months apart could be due to reinfection with the virus, but added that milder symptoms a second time could be the result of residual immunity from the first severe infection.
Danny Altmann, a professor of immunology at Imperial College London, told Sky News that while there were only 100 proven cases of reinfection worldwide, his conversations with doctors suggested that it was “much more common than we imagine.”
“Reinfection can happen quite a bit,” he said.
Professor Altmann explained that while second episodes of the disease may be less severe due to residual antibodies, a new study being carried out in Brazil offers alarming evidence to the contrary.
He said the research found that 30 healthcare workers at the same facility contracted the virus a second time, representing a 7% reinfection rate, and that they tended to suffer worse symptoms than during their first infection.
“One of them who had it mildly the first time, died the second time,” he said.
He added that it was difficult to know if those cases were the result of mutant variants of the disease or of people who did not develop antibodies.
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Vaccines ‘prevent the most serious disease’
A Siren Report from Public Health England (PHE) published in January showed that antibodies from past coronavirus infections provided 83% protection for at least five months.
The researchers, however, found 44 possible COVID reinfections among 6,614 participants who showed evidence of prior infection.
Another study indicated that up to 88% of people still have antibodies in their blood to fight the coronavirus six months after infection.
The study of about 1,700 people was carried out by the UK Biobank, whose chief scientist Professor Naomi Allen said: “Although we cannot be sure how [the presence of antibodies] is related to immunity, the results suggest that people may be protected against subsequent infections for at least six months after natural infection. “
