Taipei, June 21 (CNA) Taiwan's Central Epidemic Command Center (CECC) on Monday said the concept of a mix-and-match approach to COVID-19 vaccines will not become an option at the moment due to the lack of clinical evidence showing it works.

Chang Shan-chwen, who chairs the CECC's advisory panel, said the national Advisory Committee on Immunization Practices (ACIP) has already held a virtual discussion on the matter and advised against this idea on Sunday.

His statement came after some medical experts have called for the CECC to update its COVID-19 vaccination guidelines to allow people to receive a second dose of a different vaccine, as Taiwan recently reported several deaths among people who had received their first dose of the AstraZeneca (AZ) vaccine.

The deaths, according to the CECC, have so far not been linked to the vaccine.

Chang explained that ACIP experts have advised against vaccine mixing due to the lack of clinical evidence on such a practice, including on how it may affect a vaccine's safety or efficacy.

He said there is currently no information on the possible effects of mixing AZ with Moderna, two types of vaccine brands which Taiwan has in its inventory.

Although Taiwan's vaccination guidelines currently prohibit the practice of vaccine mixing, he said the CECC will make an exception on a case-by-case basis for people who suffer a severe allergic reaction after receiving their first dose.

The usage of vaccine mixing could possibly become a norm based on future scientific findings, Chang said.