Two doses of COVID-19 vaccine provide 65 percent protection against infection, 77 percent protection against hospitalisation, 92 percent protection against oxygen therapy, and 94 percent protection from ICU admission, according to a study of CMC Vellore health-care workers. Even a single dose provided protection against hospitalization and infection. Covishield was given to over 93 percent of people.

According to a study conducted at CMC Vellore, two doses of COVID-19 vaccine provide significant protection against infection and hospitalisation, especially among health-care professionals who are at high risk of infection. The study revealed that the vaccination to be protective, it did not investigate the proportion of cases caused by the beta (B.1.1.7) and delta (B.1.617.2) variants that have been responsible for COVID-19 second wave.

Dr. Joy J Mammen, Professor at the Department of Transfusion Medicine, CMC Vellore and the corresponding author of the preprint said that, "Our study shows that COVID-19 vaccines have a great benefit in reducing infection and severity of disease. Vaccination helps in breaking the chain of transmission."

Dr. Mammen stated that, "We were not able to individually study the efficacy of Covishield and Covaxin as only a few received Covaxin." The study revealed that vaccinated people are more protected than unvaccinated individuals."

Between January 21 and April 30, 2021, 8991 (84.8 percent) health-care employees have been vaccinated. Covishield was given to the majority of them (almost 8,400). Between February 21 and May 19, the incidence of infection and hospitalisation was studied. No death was reported among 8,958 vaccinated people and one death reported in 1,609 unvaccinated health-care worker.

The vaccines provided 65 percent protection against infection, 77 percent protection against hospitalisation, 92 percent protection against the need for oxygen, and 94 percent protection from ICU admission among the 7,080 health-care workers who received two doses, according to the study. Infection was found on average 47 days following the second dosage among fully vaccinated people.

The researchers discovered that just one dosage of COVID-19 vaccination provided considerable protection against infection and hospitalisation. Protection against infection was 61 percent in 1,878 health-care workers who got only one dosage, while protection against hospitalisation was 70 percent and protection against infection was 61%.

Professor of Microbiology at CMC Vellore Dr. Gagandeep Kang tweeted, “Vaccines are working well! Good against infection (in healthcare settings where there is a high risk of transmission), great against severe disease.” She is not involved in the study.