Delta Strain Was Behind Breakthrough Infection In India During Second COVID Wave

The Delta variant of COVID-19 is wreaking havoc around the world and is behind the third wave of the pandemic in many countries.

One of the biggest challenges Delta is posing for the world is its ability to escape antibodies.

This means that those who have been previously infected or have been immunised by vaccines are also not safe from getting re-infected.

Yale Medicine

A study in India, where the mutant strain was first identified, also points in the same direction.

Delta strain responsible

According to a study by the Indian Council of Medical Research (ICMR) on variants responsible for the second wave of COVID-19, delta strain was responsible for the breakthrough infections in the country during the second wave.

Breakthrough infection is if one gets infected even after immunisation.

The study found that though the strain caused breakthrough infections, only 9.8 per cent of cases required hospitalisation, and fatality was observed in only 0.4 per cent of cases.

BCCL

It also added that vaccination does provide reduction in hospital admission and mortality.

For the study, the Indian Council of Medical Research (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 positive for COVID-19, from 17 states and Union Territories of the country.

"The overall majority (86.09 per cent) 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," the study said.

Reuters

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 per cent) required hospitalization and fatality was observed in only three cases (0.4 per cent).

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.

AFP

Out of the 677 patients analysed, 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 Covishield vaccine, 71 had received Covaxin and two had received Sinopharm vaccine.

A total of 482 cases (71 per cent) were symptomatic with one or more symptoms, while 29 per cent had asymptomatic SARS-CoV-2 infection.

The largest of its kind study also identified two new SARS-CoV-2 variants Delta AY.1 and AY.2.

AFP

"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 the mutations known to disrupt receptor binding domain (RBD) binding capacity and make them more infectious by immune escape mechanisms against the current vaccines. This indicates improved virus fitness to evade immune responses and survive against the vaccines," the study said.

INSACOG, a consortium of government panels involved in genome sequencing of coronavirus had recently said that AY.3 has been identified as a new Delta sub-lineage and it is defined by ORF1a: I3731V common AY.1 mutations except for S: K417.