RIO DE JANEIRO, BRAZIL – To determine if someone is no longer contagious because he or she has already had the Covid-19 disease, should be possible in some countries in the near future.
Becoming immune against the novel coronavirus without even knowing it – a dream! However, this is not unrealistic, says Swiss infectologist Pietro Vernazza: “Many people contract the disease with very mild or even no symptoms, and build up an immune response”.
How often this happens is unclear. But in Iceland, for example, where a large number of people have been tested, half of those infected had no symptoms at all.
How high the immunity against the virus is afterward and how long it lasts is also still unclear. However, Vernazza says: “Everything suggests that a reasonable immunity against this virus is being built up”.
We become immune by developing antibodies against the virus – proteins that render the virus harmless. And these antibodies – there are different types of them – can be detected with a relatively simple blood test.
Blood sample rather than throat swab
These tests are different from those that are currently in such short supply – not the so-called PCR tests, in which the genetic material of the virus is detected by a smear test of the throat and nose. Blood tests to determine whether you are immune are already on the market. In Asia, in the USA, but also in Europe, confirms Hans Hirsch, a virologist at the University Hospital in Basel.
“There are commercial providers. We are in the process of comparing the two systems.” The question is how accurate these tests really are; if there were false results, people would feel insecure.
Immune health workers
Therefore it is very important that these tests be thoroughly checked. A number of laboratories are currently conducting these tests, as immune staff would be a blessing for hospitals and the health care sector, says Hirsch: “When they are fully deployed again, there are fewer protection and mask issues.”
But these tests would also be very important for private individuals, says Vernazza. He would like to see the introduction of simple tests that can be bought in drugstores, and that everyone can perform at home. Key questions could thus be answered: “Am I protected? So I don’t have to worry about infecting my grandmother if I go see her?”
The trial started with 2,000 people a day
Consequently, it is very important to verify the quality of the various tests. Some hospitals now intend to make progress in its application. One Zurich hospital, for example, intends to test up to 2,000 people a day with this new type of test this week, said Adriano Aguzzi from the Neuropathology Institute.
These immunity tests would also provide a clearer picture of the actual spread of the pandemic in a country. That, in turn, would provide an important basis for policymakers to continuously adapt measures against the pandemic.
If the calculation works out, if the tests perform well, if a growing number of immune people can be detected, and if immunity is indeed as high as expected –that would indeed be very good news.