Myth: A mixed vaccination is more effective.

Facts: COVID-19 vaccines developed by different technical approaches are not interchangeable.

The World Health Organization's（WHO) chief scientist, Soumya Swaminathan, advised people on July 12 against mixing and matching COVID-19 vaccines from different manufacturers, calling it a "dangerous trend" since there was little data available about the health impact. "It's a little bit of a dangerous trend here. We are in a data-free, evidence-free zone as far as mix and match," she said in an online briefing.

However, she later tweeted that data from mix and match studies of different vaccines are awaited - and immunogenicity and safety both need to be evaluated.

According to the Vaccination Guidance in China, vaccines of the same product type can be administered sequentially or mixed. Vaccines from different technical approaches are not interchangeable.

If special circumstances make it impossible for the vaccine recipients to complete the vaccination with the same vaccine from the same manufacturer, it is feasible to be injected with vaccine developed by the same technical approach and produced by different manufacturers.

Some scientists are conducting clinical trials on sequential immunization of COVID-19 vaccines in order to provide efficient solutions to further enhance the immune response and effectiveness of vaccines developed by various technical approaches.