MANILA – A member of the Department of Science and Technology's (DOST) vaccine expert panel has allayed fears that vaccines would no longer work after months of inoculation, amid reports that antibodies they generate also decline as time goes by.

Dr. Rontgene Solante said that aside from neutralizing antibodies, vaccines also generate what is called cell-mediated immunity or T-cells.

These cells along with another type of lymphocyte called B-cells respond to viral infections and stimulate immune response even if the level of vaccine-generated antibodies decrease.

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“Ang nakikita natin palagi na mine-measure (what we see all the time that is being measured) especially in the studies is the neutralizing antibody titer. But doon sa mga sa clinical trials they also measure the cell-mediated immunity, 'yung T-cell response which is also as equally as important as your antibody," said Solante.

"Your antibody protects us from getting the infection. But your T-cell is the one that will really kill the virus once it goes inside the body,” he added.

T-cells, or memory cells, are able to recall antibodies upon recognizing a viral infection like COVID-19, which Solante said are “responsible for the durability of protection.”

But T-cells also wane through a process known as immunosenescence. This is the depletion of T-cells occur among the elderly, in immunocompromised patients and post transplant patients who are on medication that suppresses the immune system.

This makes them at higher risk of developing severe COVID-19, he said.

BOOSTER SHOTS

While booster shots are seen by some as necessary to be able to sustain protection from the disease, Solante said current data showed that those who are fully vaccinated against the disease, or those who had 2 jabs, are still protected from developing severe to critical illness.

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He pointed out that this is also despite the presence of more transmissible COVID-19 variants.

The government earlier said they would try achieving "population protection" by the end of the year against COVID-19.

Population protection, according to the health department, means immunizing a large part of the priority sectors to prevent deaths and hospitalization due to COVID-19.

• READ: No more 'herd immunity'; gov't now eyes 'population protection' vs COVID-19

This is different from herd immunity, where the goal is "continuous" protection from the virus, which may include booster shots, among other things, amid the presence of variants.

But even if booster shots are given at the right time, government should also consider the limited COVID-19 jabs the country currently has.

“Ang unknown lang dito, kung kailangan mag-booster, at what point in time? Kasi alam naman natin na ang mga bakuna meron talagang hangganan 'yung tinatawag nating protection," he said.

(When do we need boosters? Vaccines, for a fact, really have an end when it comes to protection)

“Government is really targeting for herd immunity. If you use a booster and give it sa mga nabakunahan na instead to the non-vaccinated, medyo dehado ang hindi nababakunahan," he added.

(If you use boosters to those already vaccinated, those who are unvaccinated are on the losing end.)

He said the country should "evaluate further" if boosters would be needed at this point.

"Kung kailangan man, tingnan natin kung sino ang bibigyan ng booster dose. Depende na 'yan sa kung sino ang at risk of getting severe infection, those with comorbiditiess, immunocompromised,” explained Solante.

(If it is already needed, let us see who really needs those booster doses. It depends on who are at risk.)

Some Filipinos, especially in the capital region, have reportedly sought getting booster shots or a third dose against COVID-19 despite millions still waiting to get their first jab against the disease amid limited supply.

The National Task Force Against COVID-19 earlier warned "vaccine hoppers"— or those who get additional virus shots by going to a different local government unit— that their actions are illegal and immoral.

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Government data collected by the ABS-CBN Investigative and Research Group showed Philippine authorities have so far administered 28.3 million virus doses, of which over 15.5 million are first shots.

A total of 12.7 million people, meanwhile, are fully vaccinated against the disease.

The A3 priority sector, or people with comorbidities, is the group that has the most number of individuals fully vaccinated so far, according to the health department.

– with reports from Job Manahan, ABS-CBN News