Omicron subvariants are still the cause of Covid cases in many places in the world, and in Singapore, the Ministry of Health announced the first local cases of BA.4 and BA.5 on Sunday (May 15).
However, two new studies show that getting a breakthrough Omicron infection—meaning getting infected after being vaccinated—protects them more effectively than even a second vaccine booster jab.
The studies, conducted by BioNTech and the University of Washington in collaboration with Vir Biotechnology, looked into the immune responses of different people grouped according to their infection status and vaccination record, Fortune reported on May 16.
But this does not mean that a person should deliberately try to get infected with the Omicron variant as the risk of “long Covid,” where a person experiences symptoms months after getting infected, remains a real threat and is said to affect as many as one-third of those who have caught Covid.
In Singapore, a second booster shot has been recommended for people over the age of 80, those who live in senior care facilities such as nursing homes, and medically vulnerable persons who are at increased risk of severe disease because of significant medical risk factors.
However, individuals between the ages of 60 to 79 may also get the second booster jab if they choose to do so, the MOH said.
The second booster is given around five months after the first booster jab.
Germany’s BioNTech found that people who had a breakthrough Omicron infection showed a better response in their b-cells, the white blood cells that are part of the immune system that helps produce antibodies, than those who received boosters but were not infected.
In the study from the University of Washington, meanwhile, blood samples of people who had been vaccinated and then were infected with either the Delta or Omicron variants were compared to samples from those who were infected first and then vaccinated to those who were vaccinated but never caught Covid, and those who were infected and did not get vaccinated.
The study showed people who were vaccinated and got infected with the Omicron variant produced antibodies that mounted a strong defence against other variants, whereas people who were unvaccinated but were infected with Omicron did not show the same immune responses.
The Fortune report warned as well that immune responses, from those who have been either infected or vaccinated, do wear off after some time.
And in the US, where a surge of Covid-19 cases is expected this autumn, the Center for Disease Control said in updated vaccination guidelines last week that people who have been infected in the past three months might consider waiting until later in the year before getting a second booster.
“A 2nd booster may be more important in fall of 2022, or if a new vaccine for a future COVID-19 variant becomes available,” the guidelines say. /TISG