Amid the global shortage of vaccines against the coronavirus disease (COVID-19), a vaccine expert on Saturday, April 24, said that mixing different vaccine brands for the first and second doses may affect its efficacy rate.

While it remains to be investigated, Dr. Lulu Bravo, executive director of the Philippine Foundation for Vaccination, said in a public briefing that mixing different vaccine brands could pose "no harm" to a person

“Actually, it remains to be investigated. But there is no harm. In general, maraming mga nangyayaring ganiyan, even before, hindi lang dito sa maaaring mangyaring sa COVID (In general, a lot of things similar to that happen, even before, not just on what might happen in COVID),” Bravo said.

She said that no company has done studies where they mix their vaccines with that of other vaccine manufacturers. “That is never done before.”

But in the face of the global vaccine shortage, she noted that some companies were said to have started to consider studying the use different vaccine for the second dose.

Bravo said that mixing different vaccines could have no harm but she noted that there is a possibility that the efficacy rate will change if a different vaccine will be used.

“Kasi ganito iyan, hindi naman makakasama kaya lang iyong efficacy magbabago (This could not cause harm but the efficacy might change),” she said. “May possibility talaga na mag-iiba kung ang ginamit mo ay ibang bakuna (there is actually a possibility that it will vary if you use a different vaccine).”

“Sabi nga natin, posibleng magdagdag ka ng efficacy or tumaas, posible rin na bumaba or posibleng the same, it remains to be seen (As what we have said, it is possible that you could increase the efficacy, it is also possible that it will decrease or possibly will remain the same, it remains to be seen,” she added.