No evidence: that recovered covid-19 patients cannot be reinfected

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Dr. Abdul Razak Shaikh;

Catching Covid-19 once may not protect you from getting it again, according to the World Health Organization, a finding that could jeopardize efforts to allow people to return to work after recovering from the virus. There is currently, no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection. The WHO guidance came after some governments suggested that people who have antibodies to the coronavirus could be issued an immunity passport or risk-free certificate that would allow them to travel or return to work, based on the assumption that they were safe from re-infection, according to the statement. People issued such a certificate could ignore public-health guidance, increasing the risk of the disease spreading further. Countries like Germany and Chile is looking into giving residents immunity passports that would allow people who have recovered from Covid-19 to be excluded from restrictive protection measures and to work outside the house. Public health officials would use tests that detect antibodies to the virus to determine if someone has previously had the virus. But the WHO cautioned against this practice due to concerns that reinfection cannot be ruled out based on antibodies alone. The U.S. and others are looking into the option. While there’s a consensus that the key to ending the coronavirus pandemic is establishing co-called herd immunity, there are many unknowns. One is whether researchers can develop a safe and effective vaccine. Another is how long people who’ve recovered have immunity, reinfection after months or years is common with other human coronaviruses. Finally, it’s not clear what percentage of people must be immune to protect the herd. That depends on the contagiousness of the virus. The WHO said it’s reviewing the scientific evidence on antibody responses to coronavirus, but as yet no study has evaluated whether the presence of antibodies confer immunity to subsequent infection by this virus in humans. And while many countries are currently testing for antibodies, these studies aren’t designed to determine whether people recover from the disease acquire immunity. Released a scientific brief recommending countries refrain from issuing certificates of immunity to people who have been infected with the Coronavirus, warning there is currently no evidence that someone cannot be reinfected. The brief is a reminder that although scientists and public health experts have made great strides in their understanding of the new virus in a relatively short period of time, there’s still a lot unknown about both the SARS-CoV-2 virus and the disease it causes, Covid-19. One of the largest outstanding questions is whether humans can develop immunity to coronavirus and what immunity would look like. In their deep dive into COVID -19 immunity, scientists explain that the first issue is that immunity is not completely understood in general. For reasons scientists don’t quite understand, for some infections, your immunity never wanes. People who are immune to smallpox, for example, are immune for life. Antibodies that protect against smallpox have been found as long as 88 years after vaccination. However, even if you lose the antibodies, it doesn’t mean you are again completely susceptible to the virus. Yes, none of this is simple. Part of the reason a loss of antibodies doesn’t always result in a loss of immunity is that the body stores antibody blueprints, when exposed to a virus a person already has antibodies for, the body can use those blueprints to quickly restart antibody production. Whether this would happen with antibodies effective at fighting Covid-19 isn’t known. It is known, however, that those who have recovered from Covid-19 have a range of antibodies in their systems, some have more, others have less. The reason why isn’t yet fully understood. However, part of it. May depend on when antibody tests are administered. The body tends to have the greatest number of antibodies four to eight weeks after infection, meaning someone tested in that period may have more antibodies than someone given an antibody test later on. It could also be the case, as the WHO noted in its brief, that immune responses outside of antibodies play a key role in fighting the virus. Still, other prominent scientists note the severity of infection may affect how many antibodies one has, as well as the strength of any possible immunity. A scientist from China, he believes mild cases might not always build up protection. The scientist said studies of more serological surveys, or blood tests for antibodies, on large groups of people, are going to be needed to make better appraisals. And they need to be sophisticated, Much will depend on how sensitive and specific the various tests are, how well they spot SARS-CoV-2 antibodies when those are present and if they can avoid spurious signals from antibodies to related viruses. There, however, are problems with these tests, currently, experts have expressed concern about false positive and negative from them and those worries have cast some new, preliminary antibody studies in serious doubt. The experts we spoke to say these reports are likely due to flaws in testing. I think the risk of being infected more than once from SARS-CoV-2 is nil, says Gregory Gray, an infectious disease epidemiologist at Duke University. Should it be the case that humans are able to become immune to the coronavirus, there is also the question of how long immunity would last.