The sheer speed with which Covid-19 spread across the world, coupled with the novel nature of the virus, has meant that scientists and technicians have been playing a game of catch-up. But our knowledge, though incomplete, is now much greater than it was at the start of the outbreak, and medical systems arebetter equipped to respond.
Part of this means we’ve got better at testing for the disease – attempting to meet the demands of people who want to know if they are, or have been, infected. Dr Alex Richter leads the clinical immunology labs at the University of Birmingham, where I work, and her team has developed serology tests that detect antibodies to Sars-CoV-2. For the time being, laboratory tests such as theirs are more sensitive than commercial antibody kits. But an increasing number of the latter are becoming available around the world, many of them over the counter.
As we go further down this road, it’s important that people understand what antibodies reveal about our immune response to Covid-19, and how protective immunity works.
Basically, antibodies to Sars-CoV-2 show that you have been infected, although people with other recent coronavirus infections (which includes some common colds) may have cross-reactive antibodies, giving false positives. Serology tests vary in accuracy , but are more effective than so-called polymerise chain reaction (PCR) tests, which detect the presence of the virus itself. One reason is that they rely less on the skill of the person doing the sampling: antibodies in the blood are easier to detect than virus particles in nose or throat swabs.
Such tests provide useful information about the way an infection has […]