The Serum Institute of India (SII) has sought permission from the country's drug regulator to conduct a Phase-3 trial to evaluate the safety and immunogenicity of its COVID-19 vaccine Covovax as a booster dose in children aged two to 18 years, official sources said on May 22.

The Drugs Controller General of India (DCGI) had granted permission in March for conducting a Phase-3 clinical trial of Covovax as a booster dose in adults.

In an application, SII Director for Government and Regulatory Affairs Prakash Kumar Singh has sought permission to conduct the Phase-3, observer-blinded, randomised, controlled study in children aged two to 18 years in India who have already received primary vaccination against COVID-19 with Covovax at least six months ago.

The study will evaluate the immunogenicity and safety of the vaccine as a booster dose in comparison with the placebo. Singh is learnt to have stated that it has become evident that the protection offered against COVID-19 wanes after a two-dose schedule of vaccines and that more than 100 countries have started administering booster doses.

A total of 408 eligible children two to 18 years of age who have completed the primary two-dose schedule of Covovax at least six months ago will be enrolled in the study. The Hyderabad-based Bharat Biotech has recently sought permission from India's drug regulator to conduct a Phase-2/3 study of its COVID vaccine Covaxin as a booster dose among those aged two to 18 years.

Covovax was approved for restricted use in emergency situations in adults on December 28 last year and in the 12-17 age group, subject to certain conditions, on March 9. India began administering precaution doses of the vaccines to the healthcare and frontline workers and those aged 60 and above with comorbidities on January 10 this year.

The comorbidity clause for people aged above 60 was subsequently removed. India began administering precaution doses of COVID-19 vaccines to all aged above 18 years at private vaccination centres on April 10.

Currently, all those above the age of 18 who have completed nine months after the administration of the second dose are eligible for the precaution dose.