Virus World

New evidence suggests that people who have had COVID-19 may be immune to SARS-CoV-2, the virus that causes it, for at least 5–7 months, if not longer. Recent alleged cases of reinfection with SARS-CoV-2, the coronavirus that causes COVID-19, have raised concerns that the human immune system may only provide short-term protection against the virus. In addition, scarce research has suggested that the number of antibodies in a person’s bloodstream that is capable of disabling the virus declines sharply after an initial infection. However, scientists at the University of Arizona (UArizona) College of Medicine in Tucson have now found evidence of long lasting immunity in people who have had COVID-19. 

They tested for the presence of antibodies to the virus in nearly 6,000 individuals and then followed them up for several months. “We clearly see high quality antibodies still being produced 5–7 months after SARS-CoV-2 infection,” says Dr. Deepta Bhattacharya, an associate professor of immunobiology at the university, who co-led the research.  “Many concerns have been expressed about immunity against COVID-19 not lasting. We used this study to investigate that question and found immunity is stable for at least 5 months.”  Bhattacharya points out that people who contracted the SARS-CoV virus responsible for the 2002–2004 outbreak of SARS were still immune 12–17 years after infection. This virus is very similar to SARS-CoV-2.  “If SARS-CoV-2 is anything like the first one, we expect antibodies to last at least 2 years, and it would be unlikely for anything much shorter,” he says.  In their paper, published in the journal Immunity, the scientists also note that out of nearly 30 million cases of COVID-19 since December 2019, there have been only about 10 confirmed cases of reinfection...

Study published in Immunity (Oct. 13, 2020):

https://doi.org/10.1016/j.immuni.2020.10.004

“Immunity passports” for key workers could be a way of getting people who have had coronavirus back into the workforce more quickly, scientists and politicians in the UK have suggested. Researchers in Germany are currently preparing a mass study into how many people are already immune to the Covid-19 virus, allowing authorities to eventually issue passes to exclude workers from restrictive measures currently in place.

The study, which is yet to finalise funding, would involve testing the blood of more than 100,000 volunteers for coronavirus antibodies from mid-April. The test would then be repeated at regular intervals on an accumulatively larger sample of the population, to track the pandemic’s progress. The shadow health secretary, Jonathan Ashworth, said: “Germany appears to be leading the way in the testing and we have much to learn from their approach. I’ve repeatedly called for more testing and contact tracing in the UK, and we should be looking at initiatives like this closely.”

The results of the German study, organised by the government’s public health body, the Robert Koch Institute, the German Centre for Infection Research, the Institute for Virology at Berlin’s Charite hospital and blood donation services, would make it easier to decide when and where schools in the country could reopen, and which people are safe to go back to work. “Those who are immune could be issued with a kind of vaccination pass that would for example allow them to exempted from restrictions on their activity,” said Gerard Krause, head of epidemiology at the Helmholtz Centre for Infection Research in Braunschweig. The German government has not yet officially commented on the proposal for such a certificate made by scientists....

Studies from serum samples could transform our understanding of the spread of COVID-19, but what antibodies alone say about immunity is not yet clear. It’s months into the coronavirus pandemic and public health officials still don’t know how many people have actually contracted the culprit, SARS-CoV-2. In many countries testing capacity has lagged behind the spread of the virus. Large numbers of people have developed COVID-19 symptoms but have not been tested, and the vast majority of people who had the virus but never developed symptoms and therefore were not tested, are not reflected in official statistics.

Federal and state governments, companies, and research groups are now racing to develop antibody tests to shine a light on the true spread of SARS-CoV-2. While PCR tests currently used to diagnose cases detect the virus’s genetic material, antibody tests can screen for virus-attacking antibodies that are formed shortly after an initial infection. Those antibodies usually linger in the blood long after the virus is gone. One such antibody, or serological, test was given emergency use authorization by the Food and Drug Administration in early April, and a number of other groups are making more tests, and in some cases even deploying them.

The National Institutes of Health has launched a study to detect antibodies in order to gather data for epidemiological models. And a recent survey of residents in a German town was one of the first to use an antibody test among the public, reporting that 14 percent of people there were likely to have been infected with SARS-CoV-2 due to the presence of antibodies.