Infection with the coronavirus, either before or after vaccination, may enhance immune responses, according to a study published Tuesday in the journal Science Immunology.
The study, conducted by researchers at the Oregon Health & Science University, analyzed antibody responses in 104 vaccinated health care workers. Of this group, 31 people had a breakthrough infection after vaccination, 31 were infected before vaccination (referred to as hybrid immunity), and 42 had no history of infection.
The researchers found that both the hybrid and breakthrough groups had significantly higher levels of antibodies against Covid-19 proteins compared with the group with no infections. These antibodies were also more efficient and potent, and they had higher rates of virus neutralization: up to 32 times higher in the hybrid group and up to 17 times higher in the breakthrough group. This pattern was seen against the wild-type virus as well as the Alpha, Beta and Delta variants.
In the group with no infections, antibody levels declined with age, as previous research has found. However, this effect was not seen in either the hybrid or breakthrough groups. No significant differences were observed between the hybrid-immunity and breakthrough cohorts.
While previous studies have shown increased immune responses from pre-vaccination infections, the researchers claimed there was a gap of knowledge about responses to breakthrough infections.
“Overall, our results show that SARS-CoV-2 infection before or after vaccination gives a significantly larger boost to the neutralizing antibody response compared to two doses of vaccine alone. More importantly, the potency and breadth of the antibody response appears to improve concomitantly,” the authors state.
However, they highlight the importance of getting the vaccine, regardless of previous infection status.
“Because vaccination protects against severe disease and death, it is safer for individuals to be vaccinated before rather than after natural infection.”
Experts also warn against trying to develop or boost coronavirus antibodies by catching Covid-19 on purpose. Even vaccinated people can become severely ill or spread the virus to people around them who might be at higher risk for serious complications.
The new study did not include participants with boosters or third doses of the vaccine, though an early external study may suggest that boosters offer increases in immune protection similar to those seen in the hybrid-immunity and breakthrough groups, according to the authors.