The Union Health Ministry is expected to soon approve Biological E's Corbevax as a precaution dose for people above 18 years who are double vaccinated with either Covishield or Covaxin, official sources said on Tuesday.

The approval will be based on the recommendations made by the COVID-19 Working Group of the National Technical Advisory Group on Immunisation (NTAGI) last week, the sources told PTI.

If approved by the government, this would be the first time a booster dose of a Covid vaccine different from the one used for primary vaccination would be allowed in the country.

"Corbevax will be considered as a precaution dose after completion of 6 months or 26 weeks from the date of administration of the second dose of either Covaxin or Covishield vaccines for those aged above 18 years enabling use of Corbevax as a heterologous COVID-19 vaccine for precaution dose administration in this age group," a source said.

This will be in addition to the existing guidelines for homologous precaution dose administration of Covaxin and Covishield vaccines.

India's first indigenously developed RBD protein subunit vaccine Corbevax is currently being used to inoculate children in the age group of 12 to 14 years under the COVID-19 immunisation programme.

The COVID-19 Working Group (CWG), in its July 20 meeting, reviewed data of the double-blind randomized phase-3 clinical study which evaluated the immunogenicity and safety of booster dose of Corbevax vaccine when administered to COVID-19-negative adult volunteers of age 18-80 years previously vaccinated with two doses of either Covishield or Covaxin.

"Following the examination of the data, the CWG observed that Corbevax vaccine can induce significant increase in antibody titers when given to those who have received either Covaxin or Covishield, which is likely to be protective as per the neutralization data also," the source said.

The Drugs Controller General of India (DCGI) on June 4 approved Corbevax as a precaution dose for those aged 18 and above.

India began administering precaution doses of vaccines to healthcare and frontline workers and those aged 60 and above with comorbidities from January 10.

The country began inoculating children aged 12-14 from March 16 and also removed the comorbidity clause making all people aged above 60 eligible for the precaution dose of Covid vaccine.

India on April 10 began administering precaution doses of COVID-19 vaccines to all aged above 18 years.