The World Health Organization (WHO) has warned there will be “chaos” if people start mixing different types of Covid-19 vaccine.
The organisation’s chief scientist Soumya Swaminathan insists public health authorities must use the available data to decide how vaccines are administered, claiming individuals shouldn't take it upon themselves to mix and match jabs from different manufacturers, or decide when to have them.
Some countries are planning to roll out a third vaccine, or a booster shot, to those most at risk of becoming seriously ill from Covid-19 before winter hits later this year and there is concern about how this will be monitored.
“It’s a little bit of a dangerous trend here,” Swaminathan said during an online briefing on Monday when asked about booster shots. “It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose.”
“Individuals should not decide for themselves, public health agencies can, based on available data,” Swaminathan later said in a tweet. “Data from mix and match studies of different vaccines are awaited – immunogenicity and safety both need to be evaluated.”
A clinical trial is currently being carried out by the University of Oxford in the U.K. to determine the viability of having an AstraZeneca vaccine followed by a second dose of Pfizer or vice versa, with the Novovax Inc and Moderna Inc also being considered.
Other studies have shown no negative effects from mixing vaccines, but further research is required to validate the findings.
Some countries have considered mixing vaccines if there is a short supply of a particular one, and last month, WHO said Pfizer vaccinations could be administered after a first dose of AstraZeneca if there was no alternative.