Yesterday, President Cuomo mentioned serological testing, which could end this crisis sooner than we think. Donna and I both had a wicked run with a virus in January with symptoms that sound similar to the Covid-19, and even if it was only a cousin, maybe the antibodies will ward off the real thing. If so, I’d like to get back to work!
Just how many people actually have Covid-19? How long will it be before we can safely begin to ease social distancing? And is this a one-off crisis or are we now facing the threat of repeated waves of coronavirus pandemics on an annual basis?
These are all questions to which scientists around the globe are racing to answer through serological testing – detecting tell-tale antibodies in the blood to identify the real number of people in a population who have ever come in contact with the virus. Over the coming months, the results will determine everything from how long society’s shutdown needs to be, to evaluating the effectiveness of the new vaccines on the horizon.
Right now, the NHS tests for Sars-CoV-2 – the virus that causes Covid-19 – through a diagnostic technique called polymerase chain reaction (PCR) which detects the virus’ genetic material in oral or nasal swabs. It’s highly effective, but it only returns a positive result when the virus is still present in the body.
Serological testing will tell us how many people crossed paths with the coronavirus weeks or even months ago – sometimes without knowing – a figure which epidemiologists modelling the spread of Covid-19, and governments need to know to make accurate public health decisions.
“You’ll have heard [the UK’s chief scientific advisor] Patrick Vallance talk about herd immunity as a useful outcome if enough people have had the infection,” says Andrew Freedman, consultant in infectious diseases at Cardiff University. “That’s something you can determine if you do serologic testing on enough representative people across the country. If you find that 60 per cent or more of the population have got antibodies to the virus, so they’ve already had the infection, this would tell you that herd immunity might be successful and it’ll stop spreading. So then the government could stop the social distancing and isolation precautions at the moment.”
As the wait for new drugs for Covid-19 goes on, serological testing is also likely to be used to identify people who have recovered from the virus, who may be asked to donate their blood as a form of emergency treatment for elderly or vulnerable people that are acutely ill. This is a treatment idea for virulent infections which dates back to the Spanish influenza, more than a century ago.
“Serology can be used to identify people with high levels of neutralising antibodies that can kill the virus,” says Theel. “Their plasma would be tested, collected, screened for HIV and hepatitis, and then administered to ill patients. The idea being these antibodies could quickly activate and kill the virus in those sick people.”
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