A recent study undertaken by the All India Institute of Medical Sciences (AIIMS) found that booster injections were beneficial in reducing the frequency of Covid-19 infections. According to a study published in the medical journal Lancet, only 7% of Health Care Workers (HCWs) reported acquiring Covid-19 after taking a booster dosage during the research period.
Following an increase in instances of omicron variant reported in December 2021, a total of 11,474 HCWs from Delhi participated in the research. During the omicron transmission phase, over one-fifth of the employees were infected with SARS CoV-2, with a predominant moderate spectrum of Covid-19 illness.
“In our study, 1,363 (11.9%) HCWs took booster shots, out of which 96 (7.0%) got infected from Covid-19. We studied the density of infection and re-infection along with the effect of vaccine against the within the omicron transmission period from December 01, 2021 to February 25, 2022,” the report said.
It also noted waning effects of vaccine protection with increase in time intervals since vaccination. “We found a modest effect of Covid-19 vaccines after 2 months of completion of the second dose, and worthwhile benefits of doses beyond 6 months could be excluded. The finding is corroborated with neutralisation studies that have shown significant reduction in neutralising ability of immunity induced by vaccination,” the report said.
A team of skilled workers collected the data over the phone. All HCWs who took part in the initial round of data collection were called again to get information on immunisation history, Covid-19 testing, symptoms, and other factors.
According to the analysis, the omicron surge was associated with a higher likelihood of re-infections than prior pandemic times.