Delta variant behind majority of 'breakthrough' infections: Study
The Delta variant of SARS-COV-2 was behind the majority of clinical cases of breakthrough infection of COVID-19 but only 9.8% of cases required hospitalization and fatality was observed in only 0.4% of the cases, according to a new study by the Indian Council of Medical Research (ICMR). Breakthrough infection is if one gets infected even after immunization.
Vaccination provides reduction in hospital admission, mortality: Study
The study, the largest and first nationwide study of post-vaccination breakthrough infections from India, said its analysis shows that the vaccination does provide a reduction in hospital admission and mortality. "Therefore, enhancing the vaccination drive and immunizing people quickly would be the most important strategy to prevent further deadly waves and would reduce the burden on the health care system," the study said.
Two new variants Delta AY.1 and AY.2 were also identified
Two new SARS-CoV-2 variants Delta AY.1 and AY.2 were also identified in these study samples. "Delta AY.1 and AY.2 is characterized by the presence of K417N mutation in the spike protein region. K417N, E484K, L452R, and E484Q are mutations known to disrupt Receptor Binding Domain (RBD) binding capacity and make them more infectious by immune escape mechanisms against the current vaccines," the study said.
ICMR collected 677 samples for the study
For the study, ICMR collected 677 clinical samples (throat swab/nasal swabs) of individuals who had received two doses and one dose of vaccines (Covishield and COVAXIN) and tested COVID-19 positive, from 17 states and Union Territories of the country.
Fatality was observed in only 0.4% of cases
This study indicated the majority of cases were caused by the Delta variant and showed only 9.8% of cases required hospitalization while fatality was observed in only 0.4% of cases. "The overall majority (86.09%) of the breakthrough infections were caused by the Delta variant (B.1.617.2) of SARS-CoV-2 in different regions of India except for the northern region where the Alpha variant predominated," it said.
Study points at high community transmission of Delta during March-June
The present study revealed the infection among breakthrough cases predominantly occurred through Delta variants indicating its high community transmission during March-June followed by Alpha and Kappa variants. In the study, 67 cases (9.8%) required hospitalization, and fatality was observed in three cases (0.4%).
Seventeen states, UTs from where samples were collected
The 17 states and Union Territories from where the samples were collected are Maharashtra, Kerala, Gujarat, Uttarakhand, Karnataka, Manipur, Assam, Jammu and Kashmir, Chandigarh, Rajasthan, Madhya Pradesh, Punjab, Puducherry, New Delhi, West Bengal, Tamil Nadu, and Jharkhand. The study found that southern, western, eastern, and north-western regions of India predominantly reported breakthrough infections from mainly Delta and then Kappa variant of SARS-CoV-2.
592 were infected after receiving both doses of the vaccine
Out of the 677 patients analyzed, 85 acquired COVID-19 infection after taking the first dose of the vaccine, while 592 were infected after receiving both doses of the vaccine. A total of 604 patients had received the Covishield vaccine, 71 had received COVAXIN, and two had received the Sinopharm vaccine. A total of 482 cases (71%) were symptomatic, while 29% were asymptomatic.