Covid vaccine after infection give higher protection against illness, show 2 Lancet studies

New Delhi: Two new studies published in the Lancet have confirmed that Covid-19 vaccination provides additional protection to people who have already been infected with SARS-CoV-2, especially against severe disease.

According to the first study, conducted in Brazil, researchers found four vaccines - including the Oxford-AstraZeneca (ChAdOx1) which is widely used in India as Covishield, CoronaVac, Janssen (Ad26.COV2.S) and Pfizer-BioNTech (BNT162b2) - provide additional protection against symptomatic reinfection and severe outcomes such as hospitalisation and death in people who have already had a SARS-CoV-2 infection.

The study included over 22,000 participants.

Among people who had SARS-CoV-2 infection and were later vaccinated, vaccine effectiveness against symptomatic reinfection was 39% for CoronaVac, 56% for Oxford-AstraZeneca, 44% for Janssen, and 65% for Pfizer-BioNTech. Effectiveness against hospitalisation and death was 81% for CoronaVac, 90% for Oxford-AstraZeneca, 58% for Janssen, and 90% for Pfizer-BioNTech.

Of the 22,566 reinfection cases recorded, 1,545 people were hospitalised and 290 people died within 28 days of a positive test, it said.

Researchers say the study puts to rest the ongoing debate about whether previously infected individuals need to be vaccinated.

"All four of these vaccines have proven to provide significant extra protection for those with a previous Covid-19 infection, reducing hospitalisation and death. Our results suggest that vaccine benefits far outweigh any potential risk and support the case for vaccination, including the full vaccine series, among individuals with prior infection," says study author Julio Croda, Universidade Federal de Mato Grosso do Sul and Fundacao.