People should not do ‘vaccine shopping’ by deciding to mix and match jabs themselves, WHO warns

Soumya Swaminathan says it should be public health bodies who make these decisions

The World Health Organisation’s chief scientist has warned people against “vaccine shopping” whereby individuals decide to mix-and-match coronavirus vaccines themselves.

Soumya Swaminathan said people should follow all relevant public health advice before taking such decisions.

“I really want to caution folks because there is a tendency now for people in countries with enough availability of vaccines to voluntarily start thinking about an additional dose,” she told a press conference.

“There are people who are thinking about mixing and matching. We receive a lot of queries from people who say they have taken one and are planning to take another one.”

The WHO’s chief scientist said it was a “little bit of a dangerous trend” and there was “limited data” on a mix-and-match approach to Covid vaccines.

“There are studies going on. We need to wait for that. Maybe it will be a very good approach,” Dr Swaminathan said.

“But at the moment we only have data on the AZ vaccine – Oxford-AstraZeneca – followed by Pfizer.”

Research has found doses of these two jabs can be mixed and matched to produce a strong immune response against Covid-19, according to findings published towards the end of last month.

Countries such as France and Germany have decided to give second Pfizer doses to people who had initially received the AstraZeneca jab, which has been linked to rare blood clots in some recipients.

A growing number of countries are looking at switching to different Covid-19 vaccines for second doses or booster shots amid supply delays and safety concerns that have slowed their vaccination campaigns.

But Dr Swaminathan warned against people making their own decisions over vaccines before any public health decisions are taken in their home countries.

“It will be a chaotic situation in countries if citizens start deciding when and who should be taking a second, third or fourth dose,” she said.

Writing on Twitter, she added: “Individuals should not decide for themselves, public health agencies can, based on available data.

“Data from mix and match studies of different vaccines are awaited – immunogenicity and safety both need to be evaluated.”

Several medical studies to test the efficacy of switching Covid-19 vaccines are ongoing.

The results of a further clinical trial led by the University of Oxford that will look at mixing AstraZeneca and Pfizer as well as Moderna and Novovax vaccines is underway.

Additional reporting by Reuters