NTAGI to review Covaxin & Corbevax data for 6-12 years

New Delhi: Government advisory panel NTAGI will meet on Thursday to review data on Covaxin and Corbevax vaccines for the 6-12 age group and also deliberate on reducing the gap between the second and precaution doses from the current nine to six months. With 8,822 fresh infections being reported in a day, India's tally of Covid cases rose to 4,32,45,517 on Wednesday while the count of active cases increased to 53,637, according to Union Health ministry data.

The death toll due to the disease has climbed to 5,24,792 with 15 fatalities being reported in a span of 24 hours, the data updated at 8 am stated. The count of active cases now comprises 0.12 per cent of the total infections, while the national Covid recovery rate was recorded at 98.66 per cent, the health ministry said. An increase of 3,089 cases has been recorded in the active caseload in a span of 24 hours, the data showed.

The National Technical Advisory Group on Immunisation (NTAGI) will hold its meeting amid a fresh spike in Covid cases in the country. Currently, those aged 12 years and above are vaccinated against the virus.

The agenda for the NTAGI's Standing Technical Sub-Committee (STSC) meeting includes a discussion on a study by the CMC Vellore on the feasibility of allowing a precaution dose of a Covid vaccine separate from the one used for primary vaccination, the Covid burden in the paediatric population, and long-term safety of ZyCoV-D vaccine, official sources said.

India's drug regulator in April had granted emergency use authorisation for Biological E's Covid vaccine Corbevax for those aged five to 12 years and Bharat Biotech's Covaxin for children in the age group of six to 12 years.

The Covid Working Group of NTAGI which reviewed the findings of the Christian Medical College (CMC) Vellore study in May had found a lack of uniformity in results upon mixing of jabs for booster shots.

The study stated that the scientific evidence showed that administering a booster dose of Covishield after primary vaccination with Covaxin gives 6 to 10 times higher antibody levels as compared to when Covaxin is given as the precaution dose after a gap of six months after the primary schedule.

"However, the same advantage was not observed when Covaxin as a booster shot was given after two Covishield doses," an official source said.

Considering programmatic challenges, it was decided that the matter would be discussed in the NTAGI's STSC meeting for final recommendation.

Also, the committee in its meeting held in May cited a lack of clear evidence of the benefit of reducing the interval between the last dose of the primary schedule and the protection dose.

It felt that the studies presented for the session had valuable scientific information but were not helpful in taking a decision for the current policy question.

The ICMR was then asked to extract data from the National Vaccine Tracker Platform to determine the breakthrough infection rates at three, six and nine months after completion of the primary schedule before the onset of the Omicron wave and overlapping with the Omicron wave.

It was informed that there is no data available on the comparative effectiveness of booster/protection dose administered at six months versus nine months.

Meanwhile, the administration of Covaxin as a booster dose enhances vaccine effectiveness against Covid's Delta variant and gives protection against Omicron variants BA.1.1 and BA.2, a study by ICMR and Bharat Biotech has found.

The protective efficacy of Bharat Biotech's Covaxin following two and three-dose immunisations against the Delta variant and the efficacy of the Covaxin against Omicron variants were studied in a Syrian hamster model (animal model to study human-associated diseases), it said.

The antibody response, clinical observations, viral load reduction and lung disease severity after virus challenge were observed, it added.

The findings of the study have been published on Tuesday on bioRxiv, a pre-print server and have not been peer reviewed.

"In the Delta infection study, where we compared the protective response between the two and three-dose regimens, we could observe the advantage of the booster dose vaccination in the protection. Although the neutralising antibody levels were comparable among the groups, lung disease severity was found more reduced after the three-dose vaccination.

"The virus shedding and viral organ load were considerably reduced in both the two dose and three-dose immunised animals indicating the vaccine efficacy against Delta variant," the study by the Indian Council of Medical Research and Bharat Biotech said.