NEW DELHI: The latest study by the Indian Council of Medical Research has confirmed that the majority of the clinical cases in the breakthrough infections during the second Covid wave in India had been caused by the delta variant.
The study, based on samples from 677 people across 17 states who got Covid despite vaccination with either Covishield or Covaxin, also found 9.8% of cases required hospitalization while fatality was observed in 0.4% of cases.
“This clearly suggests that the vaccination does provide a reduction in hospital admission and mortality,” noted the authors of the paper titled “Clinical characterization and Genomic analysis of Covid-19 breakthrough infections during the second wave in different states of India”.
Tarun Bhatnagar, a scientist with ICMR’s National Institute of Epidemiology who is not directly associated with the study said that the study corroborated the dominance of delta variants in India during the second wave.
“It also shows that the breakthrough infections with the dominance of Delta suggest some level of immune escape by variant that can result in reduced vaccine effectiveness in general,” he said, adding that there is need for accelerated vaccination to reduce the impact of higher transmission property of the variant.
In the analysis researchers also examined the clinical data for 677 breakthrough cases -- 592 of whom had received both doses while 85 had got just one -- and found that a total of 482 cases or 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.
Comorbidities were observed in 154 out of 677 cases which included diabetes mellitus type II, hypertension as well as chronic cardiac, renal, and pulmonary diseases, and obesity.
The comorbid cases were significantly predisposed to develop symptoms such as cough, sore throat, fever, loss of smell and taste, diarrhoea, breathlessness, ocular symptoms and were significantly more predisposed to hospitalization, noted the authors.
It was highlighted that the current Covid19 vaccines are disease-modifying in nature wherein mild or less severe infections are expected to occur in vaccinated individuals.
However, vaccination seems to have an obvious advantage in averting severe disease, hospitalization, and deaths, felt the scientists adding that continuous monitoring of post-vaccination breakthrough infections along with clinical severity of disease must be adopted as an essential component of vaccine roll-out program by all countries.
“Such monitoring will help us to understand the need to adequately tweak the available vaccines and also develop new vaccines with enhanced potential to protect against variant strains of SARS-CoV-2,” said the paper.