Russia will soon start testing a combination of domestic-made Sputnik V and AstraZeneca vaccine. According to reports, the small study, which was scheduled to start July 26 and end in March next year, will enroll 150 volunteers and look at the mixed regimen's safety and capability to trigger immune response.
Sputnik V is a viral vector 'combination' vaccine. It uses adenovirus Ad26 in the first shot, and a different adenovirus Ad5 in the second shot for a much higher effectiveness of close to 91 per cent.
Will combination vaccines work?
Most coronavirus vaccines, except Johnson and Johnson, entail multiple doses. Two doses are important to give the fullest protection and teach the body to make antibodies and T-cells to block and kill the virus.
And, some countries are already using mixed doses. Spain and Germany are offering the Pfizer or Moderna mRNA vaccines as a second dose to younger people who have already received a first dose of the AstraZeneca vaccine, following concerns about rare but serious blood clots, rather than about efficacy.
A mix-and-match approach to COVID-19 vaccines, using different brands of jab for first and second doses, gives good protection against the pandemic virus, a UK study has found. A Com-Cov trial looked at the efficacy of either two doses of Pfizer, two of AstraZeneca, or one of them followed by the other. All combinations worked well, priming the immune system, the BBC quoted the study as saying on Monday. This knowledge could offer flexibility for vaccine rollout, the report quoted experts as saying.
-Inputs from PTI