Health practitioners are advising against the use of different brands of COVID-19 vaccines.

During the continuation of the Senate Committee of the Whole's inquiry on the government's immunization program Friday, Health Secretary Francisco Duque III said the protocol was to give individuals two doses of the coronavirus vaccines of the same brand.

"You wouldn't want to toy with the idea of giving different vaccines for the simple reason that if an adverse event following immunization does happen, or (if there is) an adverse event of special interest, we are going to struggle which of these two different vaccines must have caused it," Duque said after Senate President Vicente Sotto III raised questions from the public on the possibility of using different brands of vaccines, and whether or not they can get doses of vaccine from another brand after they are inoculated.

Dr. Lulu Bravo of the Philippine Medical Association (PMA) said using different brands of coronavirus vaccines is not recommended due to the lack of studies on its results.

"This is not recommended, your honor. Interchangeability -- that is what we call it -- is actually a no-no, because no company will be willing to do a study on that kind of a process," she said.

"Most of the results that we will get, if these were done, will not really be based on standard procedures. This is not a recommended procedure that you will interchange or use another vaccine after you have used another one before," she stressed.

Duque last January 11 said that brands of COVID-19 vaccines have various specifications which will be considered before they are administered to the beneficiaries of the government's inoculation program.

The vaccines will be used depending on the characteristics of the recipients, he said.