Home / Science / News /  Covishield dosage gap set to be cut for those aged 45 and above

DELHI : The government is considering narrowing the gap between two Covishield doses for those 45 years or older on increased availability of the vaccine and mounting criticism that the longer gap was stipulated to overcome supply constraints without much scientific evidence backing it.

The current gap between two doses of the vaccine has been set at 12-16 weeks for all adults.

The National Technical Advisory Group on Immunisation in India (NTAGI), which is slated to meet next week, has indicated that it will decide on the dosage interval in the next fortnight to a month after reviewing the scientific data collected by it.

“We have gathered data on the impact of vaccines and their dosage interval on different age groups and from different regions," Dr N.K. Arora, chairperson, covid-19 working group, NTAGI, said in an interview. “In two to four weeks, we may decide on reducing dosage interval of Covishield, especially for those above 45 years and elderly based on final scientific evidence," Arora said, adding that even a single dose of Covishield has shown a strong immune response in scientific studies.

NTAGI earlier recommended randomized trial of varying dosage interval of Covishield and other vaccines and asked the Serum Institute of India (SII), the maker of the Oxford-AstraZeneca-developed vaccine, to study the effects of varying gaps between vaccines. The two biggest users of the covid-19 vaccine are the UK and India. The UK has reduced the dosing interval to a maximum of two months.

India began with a four-week interval but later extended the gap to 4-8 weeks based on available evidence at the time. It later further expanded the gap to 12-14 weeks.

Arora said the earlier decision of four weeks was based on the bridging trial data available then. He said also that the increase in gap between two doses was based on studies that showed higher efficacy with an increase in the gap.

The government drew criticism for increasing the dosage interval as there was a shortage of vaccines in the country and the decision was seen as a move to gain time to procure more doses.

The monthly Covishield vaccine production capacity is expected to be increased from 110 million doses per month by year-end to more than 120 million, the health ministry said, citing information provided by SII.

“We do have enough doses and should cover the whole eligible population, but we don’t have spare doses. We will take a decision based on scientific evidence," Arora said.

Recently, the Union government sharply scaled back its projection of the number of covid-19 vaccine doses to be available in India by 31 December.

In an affidavit filed before the Supreme Court in June, the Union health ministry slashed its vaccine availability projection to 1.35 billion doses by the year-end from 2.16 billion doses just a month ago.

SII has also committed to supply to the World Health Organization’s Covax, an arrangement to ensure equitable distribution of vaccines across the globe. India has also been exporting Covishield to some countries.

As the projected population of 18 years and above in the country is 940 million, the total requirement of covid-19 vaccine doses for this population is 1.88 billion, according to the government. The government aims to fully vaccinate every adult by the year-end.

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