We'll soon be able to tell whether you are immune to covid-19

摘要

WE ARE getting closer to answering one of the most important remaining questions in the pandemic: how can we quickly test whether somebody is immune to the virus? This elusive measurement of immunity is known as the correlate of protection: a simple, surrogate appraisal of the entire immune response that tells you whether somebody is protected against disease or infection. "So, for example, you measure the number of antibodies in blood and find that if you have a specific number you are protected," says Christine Dahlke at the University Medical Centre Hamburg-Eppendorf in Germany. That number is a correlate of protection, or CoP. We don't yet have one for SARS-CoV-2, says Dahlke, but we urgently need one. CoPs are a standard tool in vaccinology and, although difficult to nail down, we have established them for numerous conditions, including measles, influenza and hepatitis. Getting one for covid-19 would be a boost to our efforts to end the pandemic, says Dahlke. It would allow us to bypass big vaccine trials that compare a vaccine candidate against a placebo to see the difference in infection rates. Instead, we could do simpler and quicker tests that identify whether a vaccine elicits the CoP.