After administering two doses of vaccine, fewer hospitalizations (9.8%) and deaths (0.4%) were reported in people having experienced breakthrough Covid-19 infection, emphasizing the fact that vaccination reduces hospital admission and mortality, According to pre-print study conducted by the Indian Council of Medical Research (ICMR).
During the peak of second wave, this preprint study was conducted between April and June 2021. It is one of the first and largest nation-wide study of post-vaccination breakthrough Covid-19 infections from India with 677 clinical samples.
Covaxin developed by Bharat Biotechand Serum Institute of India’s Oxford-AstraZeneca vaccine that it is locally producing as Covishield were used for the study.
““During March to June 2021, India has experienced a deadly second wave of Covid-19 with an increased number of post-vaccination breakthrough infections reported across the country. To understand the possible reason of these breakthroughs, we collected 677 clinical samples (throat swab/ nasal swabs) of individuals who had received two doses (n=592) and one dose (n=85) of vaccines (Covishield and Covaxin,) and tested positive for Covid-19, from 17 states/Union Territories of country,” said the study paper.
These cases were interviewed on telephone and clinical data was analysed. Out of 677 cases in this study, 593 were the clinical samples from breakthrough and 84 cases got infection after one dose.
While a total of 29% had asymptomatic Covid-19 infection, 482 cases (71%) were symptomatic with one or more symptoms. Fever (69%) was the most consistent followed by body ache along with headache and nausea (56%), cough (45%), sore throat (37%), loss of smell and taste (22%), breathlessness diarrhoea (6%), and 1% had ocular irritation and redness.
“This study indicated that majority of the clinical cases in the breakthrough were infected with the Delta variant and only 9.8% cases required hospitalisation while fatality was observed in only 0.4% cases. This clearly suggests that the vaccination does provide reduction in hospital admission and mortality,” finds the study.
The objective of conducting this study was to ease fears regarding vaccination. With growing concerns about protection by vaccines following the emergence of new deadly variants and reduced real world effectiveness of certain candidate vaccines against these variants.
The ICMR -Department of Health Research (DHR) used Viral Research and Diagnostic Laboratories (VRDLs) network to track breakthrough Covid-19 infections .
Breakthrough cases are defined as the detection of Covid-19 RNA or antigen in a respiratory sample collected from a person 14 days after receipt of all recommended doses of vaccine.
The study found that India’s southern, western, eastern and north-western regions predominantly recorded breakthrough Covid-19 infections from mainly Delta and then Kappa variant. The northern and central regions recorded infections due to Alpha, Delta and Kappa variants. Cases due to Alpha variant, however predominated in the northern region. The overall majority (86.09%) of the breakthrough infections were caused due to Delta variant of Covid-19 in different regions of the country except the northern region where the Alpha variant predominated, the researchers found in the study.