WHO warns against mixing and matching COVID-19 vaccines

• The chief scientist of the WHO said that in terms of vaccine mix and match, we are in an area with no data and no evidence.
• Soumya Swaminathan said that if citizens start deciding when and who will take the second, third and fourth doses, it will be a “chaotic situation”.
• An earlier study showed that mixed vaccines produce a stronger immune response.

The chief scientist of the World Health Organization (WHO) warned on Tuesday against mixing and matching coronavirus vaccines, calling it a “dangerous trend.”

“There is a bit of a dangerous trend here. In terms of mixing and matching, we are in an area with no data and no evidence,” Soumya Swaminathan said at an online briefing.

“If citizens start deciding when and who will take the second, third and fourth doses, it will be a chaotic country.”

Hybrid COVID vaccine can provide a “powerful” immune response: research

An earlier study conducted in the United Kingdom found that using a mix-and-match approach to the COVID-19 vaccine can provide a stronger immune response.

Researchers running the Com-COV study led by the University of Oxford are investigating the possibility of using alternative immunizations for potential “initial” vaccination to the development of “booster” vaccination. They say that alternating doses of the two antibodies create solid resistance .

“The UK currently has enough vaccine supply to provide all adults with two doses of the same vaccine, so the test results will not immediately affect the country’s vaccination policy,” said Professor Jonathan Van Tam, the Deputy Chief Medical Officer of the UK. The exit was notified.

But because the highest antibody response was observed in people who received two doses of Pfizer vaccine, the two mixed regimens produced a better response than two doses of AstraZeneca vaccine, Van-Tam further said:

“Our non-mixed vaccination program has saved tens of thousands of lives in the United Kingdom, but we now know that mixed doses can provide greater flexibility to our enhanced program, while also supporting countries and countries that need to further promote vaccines. Who may encounter supply difficulties.”

Some countries are currently using mixed doses. For example, due to concerns about rare but real blood clots, Spain and Germany are offering Pfizer or Moderna mRNA vaccines as a second dose to younger people who have effectively obtained the first part of the AstraZeneca antibody.

On the other hand, another study published a few months ago showed that the third dose of the AstraZeneca vaccine increases the antibody and T cell immune response, while the second dose may be delayed for up to six months and also lead to enhancement immune response.

Professor Andrew Pollard, head of the Oxford Vaccine Group, has said that it is not clear whether people need booster injections in the fall, but new data shows that existing vaccines may be effective.