The Department of Science and Technology (DOST) is eyeing to start in July the "mix-and-match" clinical trial for the vaccines against coronavirus disease, an official said on Thursday.

Some 3,000 individuals 18 years old and above will take part in the trial, said DOST Undersecretary Rowena Guevarra in the "Laging Handa" public briefing.

She said that all the vaccines in the country will be used in the mix-and-match trial with Sinovac brand as the based vaccine.

"We will have the enrollment of 3,000 participants, ages 18 and above. Now, we will have 12 experiments to be conducted with 250 (participants) each," the official said.

"Our target is by July they can start (the clinical trial)," she said.

She said the priority groups A1 or health workers, A3 or individuals with comorbidities, and A4 or economic frontliners will participate in trial using the combination of Sinovac and AstraZeneca vacine; Sinovac and Sputnik V vaccines; Sinovac and Sputnik 5 adenovirus 5 vaccines; Sinovac and Pfizer vaccines; and Sinovac and Moderna vaccines.

Guevarra said another experiment will be conducted for the "booster" using Sinovac as first and second doses and the third dose will either be AstraZeneca, Sputnik V adeno 5, Sputnik V adeno 26, Pfizer or Moderna vaccines.

"Based on this mix-and-match, we will learn whether the immune system of our people increases," she said.

According to the official, the main purpose of the mixing and mtching of the vaccines is to know if it will work.

"It means, does the efficacy of our vaccines will improve if we mix-and-match or still the same? Second, we want to ensure the safety of doing this mixing and matching because in other countries, they are also trying it, but we want to know if this mixing and matching is effective to Filipino ethnicity," Guevarra explained.

Guevarra said the DOST will secure this month the necessary clearance to conduct the clinical trial from the Food and Drug Administration and the Ethics Review Board. Celerina Monte/DMS