World Health Organization scientist Soumya Swaminathan advised individuals not to mix Covid vaccines themselves from different manufacturers, saying such decisions should be left to public health authorities.
"There is a dangerous trend here," Swaminathan told an online conference Monday after a question about boosting doses. "It will be a chaotic situation if citizens start deciding when and who will take the second dose. third and fourth. "
"Individuals should not decide for themselves, but should decide public health agencies can, based on available data," he wrote on Twitter.
Some studies are showing positive results from mixing vaccines, but these are in the first phase of research and need further study. Mixing vaccines is seen as an option in some countries where supply does not have a specific vaccine.
The WHO Strategic Advisory Group on Vaccines said in June that the Pfizer vaccine could be used as a second dose after an initial dose of AstraZeneca if the latter is not available. A Spanish study found that the Pfizer-AstraZeneca combination is very safe and effective, according to preliminary results.