Several countries have started to allow the mixing of novel coronavirus disease (COVID-19) vaccines to speed up their vaccination drive.
Some early studies have shown that combining vaccines produce a better immune response. But the efficacy of the vaccine combination is yet to be studied.
Canada, France, Norway, Spain, and the United Kingdom would allow a combination of Oxford-AstraZeneca and any other mRNA vaccines like Pfizer or Moderna.
AstraZeneca and Sputnik V are viral vector vaccines: It constitutes a safe virus that carries spike proteins of the novel coronavirus. mRNA vaccines such as Pfizer and Moderna trigger the human cells to make harmless coronavirus spike proteins.
A recent Oxford University-led study found that mixing AstraZeneca and Pfizer shots can amplify post-vaccination symptoms. China is testing a combination of vaccine doses developed by CanSino Biologics and Chongqing Zhifei Biological Products.
Russia had earlier approved clinical trials of mixing AstraZeneca and Sputnik V vaccines. But it later suspended the trial after a government ethical committee asked for more data from AstraZeneca.
The United States CDC has approved a mix of Pfizer and Moderna’s shots with a gap of at least 28 days between the two shots. As of now, India does not recommend the combination of COVID-19 vaccines due to the lack of scientific evidence.