A new study by the Indian Council of Medical Research (ICMR) has found that fewer hopsitalisations (9.8%) and deaths (0.4%) were reported in people having experienced breakthrough Covid-19 infection after two doses of a vaccine. The research indicates that a majority of the clinical cases of breakthrough infection involved the Delta variant. The study also underscores that vaccination does cut down chances of hospital admission and death.
“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,” says the preprint study.
A breakthrough case is when a fully vaccinated person later (more than 14 days after) gets the disease that the inoculation was for.
“It was observed that southern, western, eastern and north-western regions of India predominantly reported breakthrough infections from mainly Delta and then Kappa variant of SARS-CoV-2. The northern and central regions reported such infections due to Alpha, Delta and Kappa variants; however, cases due to Alpha variant predominated in the northern region. The overall majority (86.09%) of the breakthrough infections were caused by the Delta variant (B.1.617.2) of SARS-CoV-2 in different regions of India except for the northern region where the Alpha variant predominated,” the researchers say.
Of the total samples, 527 were from people who had received both doses of Covishield and 63 had got two shots of Covaxin. From the remaining 85 samples, 77 were from people who had received one dose of Covishield and eight from those who had been administered one jab of Covaxin. There were two samples from people who had received both doses of the Chinese vaccine Sinopharm.
A total of 482 cases (71%) were symptomatic with one or more symptoms, while 29% had asymptomatic SARS-CoV-2 infection. Fever (69%) was the most consistent presentation followed by body ache including headache and nausea (56%), cough (45%), sore throat (37%), loss of smell and taste (22%), diarrhoea (6%), breathlessness (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,” the report says.
The samples of those testing positive after taking the vaccine were collected by the virus research and diagnostic laboratories (VRDLs) located in the north, south, west, east, northeast, and central parts of India from 17 states and the Union Territories (UTs). The study was carried out in a bid to allay concerns about the inoculation process amid many questioning the effectiveness of the vaccines particularly against the latest and more aggressive variants of the virus.
The researchers suggest continuous monitoring of post-vaccination breakthrough infections with clinical severity of disease must be adopted as an essential component of the vaccine roll-out plan by all countries.
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