A multi-centre study on a cohort of over 31,000 vaccinated healthcare workers of a leading private facility, spanning across the country, has found that Covid vaccine provided protection against infection in "95 per cent" of the beneficiaries, hospital authorities claimed on Wednesday.
The study by Apollo Hospitals took place over four and a half months, from January 16 to May 30 and covered 31,621 healthcare workers who had received either both doses or the first dose of Covishield or Covaxin, a hospital spokesperson said.
The brutal second wave of the coronavirus pandemic was at its peak in April and May. Several doctors died during this period, and many doctors who had received double doses, were also infected in this duration.
The mega vaccination drive against Covid was launched by the government on January 16 and healthcare workers across government and private hospitals were the first ones to get the jab.
The study of healthcare workers from 43 units of Apollo, spanning 24 cities in the country was to "evaluate the incidence of post-vaccination infections (PVIs)," the Apollo Hospitals group said in a statement.
Dr. Anupam Sibal, Group Medical Director and senior pediatric gastroenterologist, Apollo Hospitals Group said, "The results showed that Covid vaccines provided protection in more than 95 per cent of the recipients and that post-vaccination infection (PVI) occurred in only 4.28% (1355 out of 31,621) of the vaccinated healthcare workers".
"The finding also showed that only 90 cases or 0.28 per cent of them required hospitalisation, with only three cases or 0.009 per cent requiring ICU admission," he claimed.
The most important finding of the study was that there were "no deaths in case of COVID infection after vaccination", he was quoted as saying in a statement issued by the hospital.
Among the cohorts, Covishield was administered to 28,918 healthcare workers (or 91.45 pc of them), while 2703 (8.55 per cent) received Covaxin. Also, 25,907 or 81.9 per cent of the healthcare workers were fully vaccinated, having received both doses of the vaccine, while 5,714 or 18.1 per cent had received only the first dose, the doctor said.
The incidence of PVI in those who had been administered Covishield was 4.32 per cent and in those who had received Covaxin was 3.85 per cent, according to Dr. Raju Vaishya, one of the authors of the study.
The healthcare workers who took part in the study, included, doctors, nurses, paramedical staff, as well as support and administrative staff, among others, the hospital spokesperson said.
The findings of the study are under consideration for publication in a peer-reviewed medical journal, the statement said.
Sibal said that "out of the fully vaccinated workers, 1,061 or 4.09 per cent reported post-vaccination infections, while 294 or 5.14 per cent of the partly vaccinated workers tested positive".
Commenting on the study, Dr. Prathap C Reddy, Founder Chairman, Apollo Hospitals Group said, "This study reiterates the fact that our mainstay against COVID-19 is mass vaccination. Vaccines are not only safe, but they also help prevent severe manifestations of COVID-19 and will help save lives."
The results of this large study across India make for a "compelling case" for citizens above the age of 18 to come forth and get vaccinated in order for us as a country to tide over the Covid-19 crisis, he said.
Reddy asserted that the country should aim to "vaccinate 5 million Indians per day consistently".
"The main conclusions from the study are that post-vaccination infections are usually minor and vaccination helps to prevent severe infection, ICU admissions, and death," he added.
While the study emphasises the fact that COVID-19 vaccines are "effective, it is important to continue with COVID-appropriate behaviours", even when fully vaccinated, such as wearing a mask, sanitising hands, maintaining social distance, and avoiding crowds, doctors said.
Vaishya, senior consultant orthopedics and joint replacement surgeon, said, "Of the 90 cases who required hospitalisation, 48 were males and 42 were females with the majority i.e., 83 cases being below 50 years of age. Of the three ICU admissions, two were males and one was a female, between the ages of 25-39, with two being fully vaccinated and one partially vaccinated."
A range of Adverse Events Following Immunisation (AEFIs) have been reported in several recipients of Covishield or Covaxin in many parts of the country. Sharing more details on the study, a senior official of the hospital said, "The majority of infections occurred after two weeks of the last vaccination dose, at an average of six weeks. 43.6 per cent of infections occurred in HCWs below the age of 30, and 35.42 per cent in those in the 31-40 year age group."
"This study period covered the second wave and the maximum infections occurred in April and May. Despite the high infection rate in the community during this period, the vaccinated HCWs were protected," he said.