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Breakthrough COVID-19 infections on expected lines: report

Swab samples are seen during a rapid antigen testing campaign for COVID-19 at a railway station in Mumbai.   | Photo Credit: Reuters

Amidst reports of rising numbers of “breakthrough infections”, or infections following two doses of vaccine, in India, a government body has said that these numbers are on expected lines, but has not officially quantified the extent of such infections.

“The number of reported vaccination breakthroughs in India are well within the numbers expected from the total number of infections, the fraction of population that is vaccinated and the known reduction in effectiveness of Covishield/Covaxin against infections by Delta. Vaccines continue to protect against severe disease and remain a cornerstone of public health strategy,” the India SARS-CoV-2 Genome Consortium (INSACOG) said in a weekly report. The INSACOG is a consortium of laboratories coordinated by the Department of Biotechnology (DBT).

Breakthrough COVID-19 infections on expected lines: report

The published efficacy of Covaxin and Covishield from Phase 3 clinical trials has shown that they range from 70%-90% but their efficacy, at preventing transmission, is significantly reduced against newer variants such as Delta. Like other vaccines, they have been designed on the older version of the virus isolated from Wuhan, China.

Last week, a study by scientists at the Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology and the Max Hospitals Group in Delhi, revealed that nearly a quarter of 600 fully vaccinated healthcare workers were reinfected.

Earlier, studies from the Christian Medical College, Vellore and Post Graduate Institute of Medical Education Research, Chandigarh, too, had reported between 1%-10% of fully vaccinated healthcare workers as having been reinfected. However, less than 5% of them have required hospitalisation and no deaths have been confirmed, indicating that vaccines continued to be effective — even against Delta variants — at preventing severe sickness and death.

The latest INSACOG report also noted that Delta continued to be the dominant lineage in India, though some of the Delta variants were in the process of being reclassified into sub-lineages comprising the ‘Delta plus’ category because of slight variations in the mutations that they manifested.

One of these Delta plus categories is called AY.12, which raised concern after being associated with several cases of breakthrough infections in Israel. However, this wasn’t yet of concern in India. “It is specifically noted that the expanding phylogenetic cluster of AY.12 that was first noted in Israel, is not yet seen in India. Similar sequences that are also being classified as AY.12 at low stringency, do not have the same epidemiological significance. A detailed update will follow,” the INSACOG noted.

There were other lineages such as AY.4 that were being tracked but they were not “clinically significant” and did not pose any additional risk compared with the Delta variants. So far, the total number of samples processed was 70,420, of which 51,651 sequences were analysed for their genomic composition, the INSACOG statement said.

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Printable version | Oct 20, 2021 12:52:16 AM |

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