NEW DELHI: According to a recent study conducted by the All India Institute of Medical Sciences (AIIMS), booster shots have proven to be effective in controlling the number of Covid-19 infections. As per the study published in Lancet, a medical journal, only 7% of the Health Care Workers (HCWs) reported of getting Covid-19 after receiving booster dose during the research period.
A total of 11,474 HCWs from Delhi took part in the study after a rise in cases of omicron variant reported in December 2021. Almost one-fifth of the workers were infected with SARS CoV-2 during the omicron transmission period, with a predominant mild spectrum of Covid-19 disease.
“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.
The data was telephonically collected through a team of trained personnel. All the HCWs who participated in the first round of data collection were again contacted to get details on vaccination history, Covid-19 testing, symptoms, among other information.
The report added that a greater risk of re-infections was observed during the omicron surge as compared to previous pandemic periods.