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Circulating mutant variants of SARS CoV2 virus may be behind the breakthrough infections being recorded in the country, public health experts have cautioned.

Breakthrough infections are those in which SARS Cov-2 RNA is detected from a person who has received the two doses of a vaccine 14 days after the second dose. The ICMR has claimed that in India 2-4 per 10,000 breakthrough infections have occurred in India with Dr Balram Bhargava, secretary, department of health research and director-general of ICMR calling it as a very “smaller number". Ongoing research and small-scale studies indicate otherwise.

A small-scale study on 113 healthcare workers who had received at least one vaccine dose at a private hospital in Delhi found that 18 tested positive for Covid but all except one had mild symptoms. The study, published in the peer-reviewed journal Diabetes and Metabolic Syndrome: Clinical Research and Reviews on May 3, was conducted on employees of the Fortis Centre of Excellence for Diabetes, Metabolic Diseases and Endocrinology in Delhi.

Out of 123 employees, 113 were vaccinated (Covaxin, 28, Covishield, 85). Second dose was completed in 107 (94.7%) and first dose in 6 persons (5.3%). Symptomatic covid-19 infections occurred in 19 persons (16.9%) post any dose of vaccine. Symptomatic breakthrough infections more than 14 days after second dose occurred in 15 persons (13.3%). Except one (required hospitalization), all 14 had mild covid-19 disease, the study found.

The scientists reviewed rigorously maintained data of vaccinations, health status, symptoms of covid-19 and RT-PCR testing of all staff such as doctors, nurses, paramedical workers, and other staff the health care facility from January 16, 2021 till date.

“Research in breakthrough infections in India should be extended to other institutions and community to obtain larger data. Breakthrough infections are important, and need more research in large medical institutions and in community. Further, it needs to be ascertained if these are caused by variants," said Dr Anoop Misra, chairman of Fortis Centre for Diabetes, Obesity and Cholesterol.

Vaccinations for covid-19 are now open to all adults in India. However, spread of covid-19 infection continues unabated.

Yet another study from Kerala on breakthrough SARS-CoV-2 infections among healthcare workers found that they were infected by virus variant B.1.1.7 a--Variant of Concern--and variants with E484K and S477N mutations in spike protein found associated with immune escape.

The scientists did genomic analysis of virus samples collected from healthcare workers who developed infection two weeks after they had received the second dose of vaccine. The analysis was done by Institute of Genomics and Integrative Biology (IGIB), New Delhi, in collaboration with the Government Medical Colleges at Kozhikode, Ernakulam and Idukki. The pre-print of the study-- “Genomic survey of SARS-CoV-2 vaccine breakthrough infections in healthcare workers from Kerala," also appeared in OSF Preprints.

Scientists at the Indian Council of Medical Research (ICMR) have however said the percentage of people who have been infected by the coronavirus after being vaccinated is not more than 0.04% in India, public health experts have called for wider studies to ascertain the real numbers and reasons behind breakthrough infections.

“No vaccine is 100% effective in preventing infection in people who have received two doses of vaccines. Some of them may be asymptomatic others may be mild. But some have reported to be severe in such cases one should suspect infection by a variant strain. It is quite possible that it is a variant strain that has caused breakthrough infection. If possible severe breakthrough infections should have a genomic analysis of the strain," said Dr Lalit Kant, a scientist and former head of epidemiology and communicable diseases at the ICMR.


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