10% ‘breakthrough’ cases hospitalised, but O2, ICU not needed: ICMR study

“This is highly significant, and underlines the crucial role of vaccines in reducing severity of the disease and mortality,” Dr Samiran Panda, Head of ICMR's Epidemiology and Communicable Diseases division, told The Indian Express.

4 min readPuneUpdated: Jul 17, 2021 07:23 AM IST

“In the larger population, we have seen about 3 to 5 per cent of patients in hospital requiring oxygen support, and about 2 per cent being put on ventilators,” Dr Panda said.

About 1 in 10 people who caught the coronavirus infection after being vaccinated required admission to hospital for treatment of the disease, a new study commissioned by the Indian Council of Medical Research (ICMR) has shown.

Crucially, none of those admitted to hospital required ventilator or oxygen support, and none had to be put into ICU.

“This is highly significant, and underlines the crucial role of vaccines in reducing severity of the disease and mortality,” Dr Samiran Panda, Head of ICMR’s Epidemiology and Communicable Diseases division, told The Indian Express.

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“In the larger population, we have seen about 3 to 5 per cent of patients in hospital requiring oxygen support, and about 2 per cent being put on ventilators,” Dr Panda said.

The study, ‘Clinical characterization and Genomic analysis of COVID-19 breakthrough infections during second wave in different states of India’ (Nivedita Gupta et al.), is the first analysis of post-vaccination breakthrough infections from all over India. It was published on the preprint server medRxiv on Friday, and is yet to be peer-reviewed.

The researchers tracked 677 individuals from 17 states and Union Territories who got Covid even after being vaccinated. Sixty-seven of these cases (9.8 per cent) required hospitalization; three of them died.

In a vast majority of the ‘breakthrough’ cases, the patient was infected with the Delta variant of SARS-CoV-2.

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“…Only 9.8% cases required hospitalization while fatality was observed in only 0.4% cases,” the study reported. “This clearly suggests that the vaccination does provide reduction in hospital admission and mortality,” it said.

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Eighty-five patients caught the infection after taking the first dose of the vaccine, while the remaining 592 were infected after receiving both doses.

A total 511 SARS-CoV-2 genomes were recovered, and an analysis determined that 443 (86.69 per cent) were of the Delta variant (B.1.617.2) that was first detected in India last year. Delta was predominant in samples from across India except the northern region, where Alpha (B.1.1.7, which was first detected in the United Kingdom) was predominant, the study says.

As Covid-19 vaccines are administered to people in countries around the world — over 31.3 crore in India had received at least one dose until Thursday — there is some concern over a small number of people getting infected with the virus even after being inoculated.

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As of July 6, the Centers for Disease Control and Prevention (CDC) in the United States had received reports of 5,186 patients with Covid-19 vaccine breakthrough infection who were hospitalised or had died. By that day, more than 157 million people in the US had been fully vaccinated, making the breakthrough rate for severe disease a minuscule 0.003 per cent.

After smaller studies reported breakthrough infections in Kerala and Delhi, ICMR in April-May commissioned the nationwide study to understand the clinico-demographic profile of patients and SARS-CoV-2 strains responsible for post-vaccination breakthrough infections. Most of India experienced a deadly second wave of the pandemic from March to June, of which a three-week period in April-May was the worst.

The researchers conducted telephonic interviews with each breakthrough case during the period May 25 to June 14, Dr Pragya Yadav, ICMR-NIV scientist and corresponding author of the study, said.

Of the 677 patients in the study, 604 had received Covishield, 71 had got Covaxin, and two had got the Chinese-made BBIBP-CorV Sinopharm/China National Pharmaceutical Group vaccine.

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The median age of patients in the study was 44. A total 441 of the breakthrough cases were males. Co-morbidities were observed in 154 out of 677 cases (23 per cent), which included diabetes mellitus type-II, hypertension, as well as chronic cardiac, renal and pulmonary diseases, and obesity.

While 482 cases (71 per cent) were symptomatic with one or more symptoms, 29 per cent had asymptomatic infection. Fever was the most consistent presentation (69 per cent), followed by bodyache including headache and nausea (56 per cent), and cough (45 per cent).

Anuradha Mascarenhas

Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues . Professional Background Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature. Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO. Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives. Awards and Recognition Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.” Recent Notable Articles (Late 2025) 1. Cancer & Specialized Medical Care "Tata Memorial finds way to kill drug-resistant cancer cells" (Nov 26, 2025): Reporting on a breakthrough for triple-negative breast cancer, one of the most aggressive forms of the disease. Discipline, diet and purpose; How a 97-year-old professor defies ageing'' (Nov 15, 2025) Report about Prof Gururaj Mutalik, the first Head of Department at Pune's B J Government Medical College who at 97 credits his longevity to healthy habits and a strong sense of purpose. 2. Environmental Health (The "Breathless Pune" Series) Long-term exposure even to 'moderate' air leads to chronic heart, lung, kidney issues" (Nov 26, 2025): Part of an investigative series highlighting that even "safe" pollution levels are damaging to vital organs. "For every 10 µg/m3 increase in PM2.5 level, there was 6-8% jump in medicine sales" (Nov 23, 2025): Using commercial data to prove the direct link between air quality and respiratory illnesses in Pune. 3. Lifestyle & Wellness News "They didn't let cancer, diabetes and heart disease stop them from travelling" (Dec 22, 2025): A collaborative piece featuring survivors who share practical tips for traveling with chronic conditions. At 17, his BP shot up to 200/120 mmHG; Lancet study flags why child and teen hypertension doubled between 2000 and 2020'' (Nov 12,2025)--A report that focusses on 17-year-old-boy's hypertensive crisis and reflects the rising global trend of high blood pressure among children and adolescents. 4. Scientific Recognition & Infrastructure For promoting sci-comm, gender diversity: IUCAA woman prof highlighted in Nature" (Nov 25, 2025): Covering the global recognition of Indian women scientists in gender studies and physics. Pune researchers find a spiral galaxy like the Milky Way from early universe'' (December 3, 2025)- A report on how Indian researchers discovered a massive galaxy that existed when the universe was just 1.5 billion years old , one of the earliest to have been observed so far. Signature Beat: Health, Science & Women in Leadership Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions. ... Read More

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