Science: The New Delhi epidemic highlights the serious challenge of achieving herd immunity in the face of Delta variants

An international team of scientists wrote in the journal Science that the severe COVID-19 outbreak in Delhi, India in 2021 showed that the Delta variant of SARS-CoV2 is not only extremely contagious, but it can also infect other people who have been infected before.

In the first wave, SARS-CoV-2 spread widely in India.

Since Delhi's first case of COVID-19 was detected in March 2020, the city has experienced multiple outbreaks in June, September and November 2020

In April 2021, the situation reversed drastically.

In a study published today, an international team of scientists used genomic and epidemiological data, as well as mathematical models to study the epidemic

To determine whether the SARS-CoV-2 mutation caused the Delhi outbreak in April 2021, the team sequenced and analyzed virus samples from the last outbreak in Delhi from November 2020 to June 2021

Through mathematical modeling of epidemiological and genomic data, the researchers found that the Delta variant is 30-70% more infectious than the previous SARS-CoV-2 lineage (including the Alpha variant) in Delhi

In order to find actual evidence of reinfection to support their modeling efforts, the researchers checked a group of individuals recruited by the Council of Scientific and Industrial Research (CSIR) of India

When the research team sequenced samples of all vaccine breakthrough cases in one center during the study, they found that in the 24 reported cases, the delta descent was 7 times more likely to cause the vaccine breakthrough than the non-Delta descent

Dr.

Professor Ravi Gupta from the Cambridge Institute of Immunization and Infectious Diseases, University of Cambridge, UK, said: “The concept of herd immunity is critical to ending the epidemic.

Previous studies led by Professor Gupta have shown that the delta variant is likely to be spread through its ability to evade neutralizing antibodies and enhanced infectivity

This research was supported by the Indian Ministry of Health and Family Welfare, the Council of Scientific and Industrial Research, and the Department of Biotechnology

Referring Mahesh Dhar, Robin Marwal, Radhakrishnan VS , Kalaiarasan Ponnusamy, Bani Jolly, Rahul Bhoyar the like

Magazine

science

DOI

10.

Article title

Genomic characteristics and epidemiology of an emerging SARS-CoV-2 variant in Delhi, India

Article publication date

October 14--2021