The Centre on Wednesday approved Hyderabad-based drugmaker Biological E’s Corbevax as a precautionary dose for those above 18 years of age and fully vaccinated with either Serum Institute’s Covishield or Bharat Biotech’s Covaxin.

So far in India, the third dose against Covid-19 had to be of the same vaccine used for the first and the second shot.

Union Health Secretary Rajesh Bhushan said in a letter to states and Union Territories that Corbevax can be administered as a precautionary dose after the completion of six months or 26 weeks from the date of the second dose.

There will no changes to guidelines for administering precaution doses of the same vaccine as the one used for first and second doses, Bhushan said.

“All necessary changes in regard to the administration of heterologous precaution dose using Corbevax to those who are eligible and due for precaution dose have been made on the Co-Win portal,” he said. “This provision would be live from 12th August [Friday], 2022.”

Bhushan said that about 97% of citizens above 12 years of age have received at least one vaccine dose, while about 89% of citizens have received both doses.

Dr Vikram Paradkar, vice-president of Biological E, told that the National Technical Advisory Group on Immunisation reviewed and recommended Corbevax as a precautionary dose in July.

“Corbevax received various approvals between December 2021 till June this year,” he added.

In June, the Drugs Controller General of India had approved Corbevax as a heterologous booster. A heterologous booster is when individuals are administered a dose of a different vaccine than what was used in the primary vaccination, according to the World Health Organization.

Biological E’s vaccine was later sent for a review to the National Technical Advisory Group on Immunisation. The company conducted a clinical trial involving 416 volunteers between 18 and 80 years of age.

Corbevax is made up of the coronavirus’ “spike protein”, which the virus uses to latch on and enter human cells. When injected, this is expected to trigger an immune response in the body.

In February, the Drugs Controller General of India gave emergency use authorisation to Corbevax for those aged between 12-18 years. In April, the drug regulator gave the vaccine emergency use authorisation for the 5-12 age group.

However, the World Health Organization has not yet given emergency use listing to Corbevax. The listing is aimed at expediting the availability of a medical treatment for persons affected by a public health emergency. Many countries require foreigners entering its territory to have received a Covid-19 vaccine that has been granted emergency use listing by the World Health Organization.

India made precautionary doses of Covid-19 available for adults at private vaccination centres from April 10. The booster jabs were first administered to healthcare workers and frontline workers in January.

On Wednesday, India reported 16,047 new coronavirus cases. The country’s active caseload stood at 1,28,261, according to the health ministry. The Centre said that 11.27 crore precautionary doses have been administered so far.