India is all set to kickstart a trial for testing Biological E’s Corbevax booster doses on those who are vaccinated with two doses of Covishield or Covaxin. The phase-3 clinical study will primarily evaluate the immune response and safety of single-dose Corbevax vaccine for booster protection against Covid-19, according to the approved protocol by the Drugs Controller General of India (DCGI) accessed by News18.com.
In December, the Corbevax vaccine was approved by the DCGI and the nod for conducting trials of booster doses was also given.
The trial will include participants between or equal to 18 to 80 years of age and took the last dose of primary vaccine six months ago. It will recruit participants who are medically stable vaccine-primed adult males and females “with and without comorbidities”.
A total of 360 subjects will be enrolled into one of the two groups for safety and immunogenicity assessment. “A total of 180 volunteers who were primed 6- 8 months ago with Covishield vaccine will be enrolled into group-I and volunteers who were primed 6-8 months ago with Covaxin will be enrolled into group-II,” the protocol said.
All participants, as per the document, will receive a 0.5 ml single dose of Corbevax intramuscularly. The participants will be followed up for a period of 28 days for any safety issues.
The study will be conducted in approximately eight centres spread across India. However, the protocol mentions that a final call is yet to be taken on the total number of sites.
“The actual duration of study participation for each subject is approximately one month,” the protocol said.
Data on side effects, immune response against variants
According to the nine-page protocol, the secondary objective of the trial is to “assess the safety, tolerability and reactogenicity of single intramuscular booster dose of Corbevax vaccine in healthy adult males and non-pregnant females primed with either Covishield or Covaxin”.
This means the trial will study if the booster shot is safe and tolerable among individuals inoculated using other vaccines. It will also observe reactions, if any.
The other objective is “to assess immune response against variants (Beta and Delta or other relevant variants) at Day-28 post booster dose”.
The study will capture data – under the primary endpoints – virus neutralising antibodies against SARS-CoV-2 at baseline and again at 28 days post booster dose.
The study will look for the proportion of participants with more than or equal to twofold and fourfold rise in “anti-RBD IgG antibodies and neutralizing antibodies from pre-booster levels along with their geometric fold rise (GMFR) at day 28”.
It will also collect information on the proportion of participants who reported adverse reactions or symptoms during the first 60 minutes of the post-vaccination observation period and for subsequent seven consecutive days (day 0-6).
It will also include information on the proportion of participants with adverse events (AEs) during the 28-day follow-up period; “serious adverse events (SAEs), if any, during the entire study period,” the protocol said.