Previous infection with the omicron subvariants BA.1 or BA.2 protects vaccinated individuals four times more from infection with BA.5 than no infection. At the same time, the EMA has now approved a vaccine adapted to BA.4 and BA.5.
Previous infection with the omicron subvariants BA.1 or BA.2 protects vaccinated individuals four times more from infection with BA.5 than no infection. This is shown by a study from Portugal. The research was published in the New England Journal of Medicine.
The researchers had access to the national registry of Covid-19 cases. All SARS-CoV-2 infections in the population aged 12 and over residing in Portugal were recorded. The virus variant of each infection was determined taking into account the date of infection and the variant dominant at the time.
Infection with omicron variants BA.1 and BA.2 protects against BA.5
“Vaccinated people who have been infected with the omicron subvariants BA.1 and BA.2 have about four times the protection against infection with the subvariant BA.5, which has been circulating since June, than vaccinated people who were never infected “, explains co-study leader Prof. Luís Graça from the Instituto de Medicina Molecular João Lobo Antunes and the Faculty of Medicine of the University of Lisbon. Infection with the omicron variants BA.1 and BA.2 thus protects against BA.5.
Infections in 2020 and 2021 that occurred through infection with earlier variants of SARS-CoV-2 virus (alpha and delta variants) also confer protection against infection from the newer omicron variant, albeit not so is high. The protection of infected vaccinees is called hybrid immunity.
Shows benefit of adapted vaccines
The results are also important for the evaluation of the vaccines adapted to Omicron-BA.1 and allow to anticipate their usefulness, adds Luís Graça. Corresponding vaccines have been available in Germany since September 5th. The European Medicines Agency (EMA) has also approved a vaccine from Biontech/Pfizer adapted to BA.4 and BA.5. It could be available in Germany from the end of September.
At the same time, there is currently a lot of discussion about the benefits of a second booster vaccination or a fourth vaccination. It should not take place before six months after the last infection or vaccination. The STIKO recommends them for people over 60 years of age and people over 5 years of age with an existing underlying disease. Since protection against a serious illness is particularly important, they should not postpone a possible vaccination date in order to wait for a vaccine that is even better adapted to the currently circulating variants. It remains to be seen whether the adapted vaccines can also prevent infection.