India is set to allow mix-and-match inoculation, with people free to choose the first jab of one vaccine and the second jab of a different one, as it moves to overcome supply constraints and evidence grows that the practice is not only safe but also produces a strong immune response.
The covid-19 working group of the National Technical Advisory Group on Immunisation (NTAGI) is considering allowing mixing and matching, but with one restriction—both doses will need to be from similar platforms. That’s to say, a person getting Covishield as the first vaccine can opt for a second dose of the Sputnik V shot because both the vaccines use adenoviruses to deliver antigens to the body. Similarly, people can get the first dose of Pfizer’s covid vaccine and the second dose of Moderna’s as both are mRNA jabs.
The final decision, officials said, would be taken after considering scientific evidence. “We would allow mixing and matching of some covid vaccines. If a common platform for the development of two different covid vaccines is used, then two doses of different vaccines may be taken,” Dr N.K. Arora, chairman of NTAGI, said in an interview.
The government, however, will continue to encourage people to use the same vaccine for both doses. “The main purpose of such mix-and-match is only for making vaccination easy. People who are not getting the second dose of the same vaccine due to reasons ranging from unavailability of the brand to access may go for mix-and-match,” Arora said. “A formal advisory in this regard will soon be released.”
NTAGI will meet later this month.
Covishield, developed by AstraZeneca Plc and the Oxford University and manufactured in India by Serum Institute of India, uses an adenovirus vector to encode the SARS-CoV-2 spike (S) glycoprotein. Sputnik V is also an adenovirus vector vaccine developed by the Gamaleya Research Institute of Epidemiology and Microbiology in Russia.
The Russian Direct Investment Fund (RDIF, Russia’s sovereign wealth fund), which markets the Sputnik vaccine, last week announced initial safety results of the world’s first study of a combination between the AstraZeneca vaccine and the single-dose Sputnik Light vaccine in Azerbaijan.
Studies on the safety and immunogenicity of the combination of the AstraZeneca vaccine and Sputnik Light vaccine in Azerbaijan began in February. To date, 50 volunteers have been vaccinated, and new participants are invited to join. Interim analysis of data demonstrates a high safety profile for the combined use of the vaccines with no serious adverse events or cases of coronavirus after vaccination, RDIF said.
The World Health Organization (WHO) last week issued interim recommendations on recombinant vaccines such as Covishield and Sputnik, saying that if different covid vaccines are inadvertently administered in the two doses, no additional doses of either vaccine are recommended at this time.
The WHO also said studies of immune responses after the first dose of a recombinant jab, followed by an mRNA vaccine, showed higher neutralizing antibody levels and T cell-mediated immune response than two doses of Covishield. They are at similar levels to those administered two doses of mRNA vaccines and better than when Covishield followed the first dose of an mRNA vaccine.
An observational study using ChAdOx1-S (recombinant) products followed by Moderna also showed increased but acceptable reactogenicity. While these studies are encouraging, they require cautious interpretation given the limited sample size and lack of follow-up, especially related to safety data, the WHO interim guidance said.
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