A SENIOR citizen got injected with his first dose of the Sinovac vaccine at the Mega vaccination facility at the Marikina Sports Complex on June 15. — PHILIPPINE STAR/ MICHAEL VARCAS

By Brontë H. Lacsamana 

THOUGH booster shots of coronavirus disease 2019 (COVID-19) vaccines have been proven safe based on a few limited studies, their efficacy remains inconclusive amid ongoing trials, according to doctors in a webinar on booster shots organized by the University of the Philippines (UP).   

“More antibodies produce stronger affinity,” said the Department of Science and Technology’s Vaccine Expert Panel chief Dr. Nina G. Gloriani, referring to antibodies that develop over time after vaccination. “Therefore, there is wisdom in waiting for the right time to boost. Hindi po pwedeng agad-agad. [We can’t do it right away].”  

She cited a study by Wang et al. which found that a third booster dose of an inactivated vaccine produced better neutralization of COVID-19.  

“The optimal timing for when to get a booster also depends on each vaccine’s dosage requirement or duration of immunity,” Dr. Gloriani said. 

According to National Institutes of Health professor Dr. Marie Carmela M. Lapitan, there are, thus far, 21 reports worldwide on boosters, all of which show a significant increase in antibody titers that are effective in preventing infection — they are, however, observational studies that have short follow-ups and thus provide low certainty evidence.  

There are ongoing trials, one of which is being conducted in UP-Philippine General Hospital.  

Huwag muna tayo tumalon agad sa ating mga booster shots kung ang vaccines natin ngayon under emergency use authorization (EUA) pa,” said Food and Drug Administration (FDA) Director-General Rolando Enrique D. Domingo. “Aaralin pa natin nang husto ’yan. [Let’s not jump the gun on booster shots while our vaccines are still under EUA. We need to conduct further studies.]”  

Emergency use of booster shots, he added, will be granted on the condition that they are effective, that the potential benefits outweigh risks, and that there is no adequate alternative treatment.  

Six congressmen recently filed a resolution for the government to provide booster shots for frontline health workers and patients. While the FDA recently allowed Pfizer and Moderna vaccines to be used for children as young as 12 years, the Philippine government has said that health workers, seniors, and people with comorbidities will still be prioritized due to supply issues.   

In light of the growing number of individuals getting a third shot ahead of those who haven’t even gotten a first, the World Health Organization and the Department of Health both previously warned the public in August that boosters do not guarantee protection against the Delta variant of the coronavirus.  

The Philippines has received close to 66 million doses of coronavirus vaccines. Around 19.38 million people or 25.12% of adults had been fully vaccinated as of Sept. 22.