Whether traveling or dining: those who have recovered from corona enjoy the same freedom as those who have been completely vaccinated – but only up to six months after the infection. Then it’s time to test or get vaccinated. Is this time limit really useful and necessary?
The six-month period lacks a scientific basis
No, says Sebastian Ulbert, Head of the Vaccines and Infection Models Department at the Fraunhofer Institute for Cell Therapy and Immunology in Leipzig. “This six-month rule now lacks a scientific basis.”
How was the six-month deadline set at all? The data available at the time had proven a protection of about eight months, explains Thomas Mertens, chairman of the Standing Vaccination Commission (Stiko). The six months would mean a two-month safety margin.
Those who have recovered are protected even after one year
For Ulbert, the six months are now set too short. In the case of SARS-CoV-2, there is enough data to show that those who have recovered are often well protected even one year after infection, even against variants such as Delta. In the case of vaccinated people, this cannot be said so far, as the studies have not yet run long enough. However, many vaccines generally achieved “at best the immunity of a previous infection,” explains the expert.
Carsten Watzl, Secretary General of the German Society for Immunology (DGfI), says that protection for those who have recovered does not decrease as much over time as for those who have been vaccinated. Watzl therefore thinks about the status of the approximately four million recovered in Germany: “The six months were an estimate, today the period could be extended.”
Infection apparently leaves behind long-lasting protection
The digital vaccination certificate of the fully vaccinated is initially valid for twelve months and is therefore twice as long as the convalescent status. The certificate must then be renewed. It is currently unclear whether this will require a booster vaccination and thus an additional entry in the vaccination card. Those who have recovered currently have to be vaccinated once after six months in order to be considered certified protected again.
An immune response triggered by an infection is “about stimulating a long-term immunological memory,” explains Ulbert. In the case of the new type of corona virus, it was initially assumed that the infection would not leave any effective long-term protection, explains the expert. But that is now out of date. For Ulbert this means in concrete terms: “If those who have recovered are at least as well protected, they cannot – unlike those who have been vaccinated – be treated again after six months as if they had never seen the virus.”
Reconsider when to re-vaccinate
According to Watzl, a previous infection protects against a renewed illness with about 80 percent effectiveness. According to the immunologist, the protection on average is similar to that of vaccinations, but it is probably quite variable. That is, some who have gone through the disease show antibody levels like those who have been vaccinated. But it also happens that those who have recovered have few or no detectable antibodies. Nevertheless, according to Watzl, they could be protected from a severe corona infection by T cells – i.e. memory cells.
Because of the unclear protection, from an immunological point of view, it is best for those who have recovered to get vaccinated after a certain period of time, advises Watzl. Stiko is considering extending this over the six months, explains Mertens. Because the infection works like a first dose of vaccine, only one dose is necessary later. Watzl: “Then you have very good protection.” Ulbert also makes it clear: “I am not against vaccinating convalescents, the timing just needs to be reconsidered.”
Data show protective effects after infection for 6-10 months
There is still no vaccination recommendation for children under 12 years of age. For those who have recovered, the same applies to those who have been fully vaccinated after six months. For Watzl, it would be better overall “if we could measure immunity,” he says. But they are not that far yet.