The ICMR study indicates that variants that are believed to be behind the resurgence of covid cases in India were introduced by foreign travellers and transmitted within the country by migrant workers and those attending religious gatherings
Coronavirus variants that are believed to be behind the resurgence of covid cases in India were introduced by foreign travellers and transmitted within the country by migrant workers and those attending religious gatherings, according to a study led by the Indian Council of Medical Research (ICMR).
The study indicates that the SARS-CoV-2 variants (variant of concern (VOC), variant under investigation (VUI) or variant of interest, variant of high consequence and double mutant) were not observed during the early phase of virus transmission (January–August).
“This analysis demonstrates that the SARS-CoV-2 variant was not reported to be circulating in India until August, the samples of which were downloaded on 9 December 2020. The circulating clades in the country may be attributed to the early introduction into India through travellers as well as the mixing of clades," said Dr. Pragya Yadav, a scientist at the National Institute of Virology (NIV)-ICMR in Pune.
“Besides, the early transmissions could be chiefly traced to movements of migrant workers and the holding of religious gatherings. The independent identification of the amino acid mutations observed in the SARS-CoV-2 variants from the early phase samples indicates an evolutionary trend in the current circulating strain that is geared towards host adaptation," she said in the study, which was published in the peer-reviewed Multidisciplinary Digital Publishing Institute (MDPI) journal Viruses on Tuesday.
The study looked at the geographic distribution of the virus clades (group of similar viruses) and variants circulating in different parts of India between January and August 2020. Around 1,603 samples were collected from 25 states and Union territories (UTs) in India
During the first covid-19 wave in India, the maximum number of cases were reached during September and October 2020 and subsequently declined until February 2021. The exponential upsurge in cases in the second wave was observed from April, with more than 200,000 new cases being reported on 17 April.
Three variants, i.e. B.1.1.7 lineage, variant of concern (VOC) and B.1.351 lineage have been reported in India. These variants are of concern due to “antigenic drift, increased transmissibility, and immune escape (especially for B.1.351) mechanisms," the ICMR said. Recently, a new lineage (B.1.617) was identified in Indian SARS-CoV-2 sequence, with the E484Q and L452R mutation (commonly known as a double mutant) in the spike protein of SARS-CoV-2, which is considered to have a higher transmission rate.
“The SARS-CoV-2 sequence analyses during the period between January and August 2020 revealed the presence of the E484Q mutation in the spike protein. These sequences were found in Maharashtra in March and July 2020. Another immune escape mutation, the N440K amino acid in the spike protein, was also observed in Telangana, Andhra Pradesh, and Assam from May 2020," according to the study