The third dose: More Filipinos now marked for anti-COVID booster shots

By: Kurt Dela Peña - 3 years ago

Dr. Glenn Mathew Baggao, chief of the Cagayan Valley Medical Center (CVMC), gets his booster shot of Pfizer vaccine against COVID-19 on Wednesday, Nov. 17. (Photo courtesy of CVMC)

MANILA, Philippines––A third shot has been deemed by experts as needed because of the waning efficacy of two doses of vaccines against SARS Cov-2, the virus that causes COVID-19.

In the Philippines, this third dose has been administered starting on Nov. 17 on health care workers after health authorities declared that booster shots were necessary, too.

READ: Health workers get first crack at COVID-19 booster shots

Last March 1, the government rolled out its vaccination campaign giving priority to health workers. By Oct. 28, the Department of Health (DOH) said 95.2 percent—1,560,938 out of 1,638,917—of health care workers had already received complete vaccine doses.

Vaccines, according to the World Health Organization-led Global Alliance for Vaccines and Immunization (GAVI), offer “life-saving protection against a disease that has killed millions.”

Last May, the DOH said while vaccinated individuals may still contract the virus, vaccines prevent severe illness and death, essential to those at high infection risk.

Graphic by Ed Lustan

However, Dr. Rontgene Solante, who is part of the government’s Vaccine Expert Panel, told INQUIRER.net that protection from COVID provided by vaccines “waned through time,” saying that individuals, six months after receiving the second dose, could develop infection and symptoms.

This was the reason why vaccine czar Carlito Galvez said last October that the government wanted to give booster shots to health care workers, taking into consideration the reality that vaccines have “waning efficacy”.

Starting Nov. 22, the government will administer booster shots to the elderly and also to individuals with immunodeficiency and active malignancy, people with HIV, transplant patients and those getting immunosuppressive treatments.

READ: Seniors, persons with comorbidities to get booster jabs starting Nov. 22 — DOH

Diminishing?

Last July, calls for the government to give booster shots, especially to health care workers, grew louder as Chinese researchers said antibodies triggered by Sinovac Biotech’s vaccine had waned six months after the second dose.

While the Chinese study was not yet peer-reviewed, it said among individuals who took part in the research—those who received two doses with an interval of two or four weeks—16.9 percent to 35.2 percent retained antibody protection.

A study by Public Health England last September revealed that 20 weeks after the second dose, the efficacy of Oxford’s AstraZeneca in preventing symptomatic COVID-19 illness, especially cases of the highly transmissible variant Delta, fell from nearly 70 percent to 50 percent.

The effectiveness of Pfizer-BioNTech’s vaccine likewise waned 10 weeks after the second dose—from 90 percent to 70 percent, the United Kingdom data showed, emphasizing that results indicated that there is “waning effectiveness against symptomatic disease.”

It said, however, that the effectiveness of the two vaccines in preventing hospitalization and death is still high 20 weeks after the second dose—Pfizer-BioNTech with 95 percent and 90 percent in preventing hospitalization and death while AstraZeneca having 80 percent efficacy in preventing hospitalization and death.

Vaccines of Moderna and Johnson & Johnson, a United States study published in Science said, saw declines in effectiveness against infection six months after the complete dose—Moderna with 89.2 percent to 58 percent while Johnson & Johnson’s Janssen with 86.4 percent to 13.1 percent.

The research showed that the vaccines “remained protective against death” in individuals who were infected by Delta—Moderna with 81.5 percent efficacy while Janssen with 73 percent.

While there were declines in efficacy, researchers said vaccines still provided protection against severe complications and death, adding that getting vaccinated against SARS Cov2 was essential as it can protect an individual against the worst outcomes of the disease.

Last Nov. 4, considering the waning efficacy of vaccines, OCTA Research’s Guido David said cases in the Philippines could increase again if booster shots were not administered, explaining that there were nations which experienced a rise in cases because the efficacy of vaccines has already diminished.

READ: OCTA Research warns spike in COVID cases if booster shots not given

PH way

The Philippines’ plan to give booster shots, especially to health care workers, dates back to May 18 when the Department of Science and Technology (DOST) told the Philippine News Agency that there was a need to conduct clinical trials on a third vaccine dose.

Last Nov. 17, as 2,488 health care workers were the first to receive booster shots, the Philippines became the sixth nation in Southeast Asia to administer the third dose. The Philippines was next to Singapore, Cambodia, Brunei, Malaysia, and Thailand.

READ: Priority groups to get COVID-19 booster shots starting November – Galvez

Looking back, here’s the Philippines’ way of giving out the booster dose:

May 18, 2021

The DOST and DOH agreed to conduct clinical trials, saying that experts will try using the same brand of vaccine for the first and second doses and a different brand for the booster shot.

July 27, 2021

The DOH said the Vaccine Expert Panel is still looking at the possibility of giving out booster doses to individuals who received Sinovac Biotech’s COVID-19 vaccine. Health Secretary Francisco Duque III said the “immunocompromised will likely be prioritized.”

Aug. 27, 2021

The DOH said giving out booster shots is still not recommended because of lack of evidence to back its safety and the lack of a steady count of doses for individuals who have not yet received first and second doses.

Sept. 5, 2021

The DOST, through the Task Group on Vaccine Evaluation and Selection, said the DOH will have the final decision regarding the booster doses, explaining that the DOST will only give a recommendation.

Sept. 14, 2021

Galvez said the government is already in active discussion with four companies producing the vaccine brands Pfizer-BioNTech, Moderna, Coronavac of Sinovac and Astrazeneca for possible purchase of booster doses.

Oct. 8, 2021

Galvez said the government wants to give out booster doses to health care workers by November or December to give them additional protection against the disease.

Oct. 18, 2021

The DOST said the dry run for the mix and match clinical trials of vaccines started in Marikina City to “know if you can have a third dose of a vaccine brand that is different from that of your first two shots.”

READ: As booster shots loom, mix and match of vaccines get closer look

Oct. 21, 2021

Duque approved an Oct. 13 recommendation by the Health Technology Assessment Council (HTAC) to give booster shots to selected individuals provided that there was enough vaccine supply and the Philippines’ initial vaccination targets are reached first.

READ: DOH approves COVID-19 booster shots for health workers, seniors

Oct. 25, 2021

The DOH said it was still waiting for the complete recommendation of the Strategic Advisory Group of Experts on Immunization, saying that it is already planning how to give booster doses while waiting for the Food and Drug Administration’s (FDA) Emergency Use Authorization (EUA).

Oct. 26, 2021

As Duque approved the recommendation of the HTAC, Galvez said health care workers, the immunocompromised and the elderly will be first in line for the third doses, explaining that two million doses will be allocated for health care workers and five million for the immunocompromised and the elderly.

Nov. 3, 2021

The FDA said four vaccine makers asked the agency for amendments to their EUA to include a third dose, sending scientific data available for FDA experts to look at.

Nov. 15, 2021

The DOH announced that health care workers, starting Nov. 17, may already receive booster doses, saying that the guidelines will be released by the National Vaccine Operations Center (NVOC).

Nov. 16, 2021

The FDA approved the use of four vaccine brands as booster doses for completely vaccinated individuals—Pfizer-BioNTech, Astrazeneca, Coronavac by Sinovac and Sputnik. It said the doses will be given to health care workers, the elderly and those with existing illnesses.

Nov. 17, 2021

The Philippines started giving booster doses to health care workers, allowing them to choose the brand of vaccine they want. The DOH likewise issued a 15-page guideline.

READ: Health workers can choose COVID-19 booster shot, says DOH

Nov. 20, 2021

The Inter-Agency Task Force for the Management of Emerging Infectious Diseases approved the administration of booster shots to overseas Filipino workers. However, it has not yet been given a definite date.

Nov. 21, 2021

The DOH announced that starting Nov. 22, the elderly may already receive booster doses while individuals with immunodeficiency and active malignancy, people living with HIV, transplant patients and those getting immunosuppressive treatments may already have the third dose.

Things to know

Solante said there are two types by which vaccines can boost the primary series—homologous and heterologous. If you’re already set to get a booster dose, here’s what you need to know:

Homologous means giving out an additional dose from the same brand of vaccine used in the primary series. Heterologous means administering an additional dose of a brand different from the brands used in the primary series.

Graphic by Ed Lustan

The DOH said those who are willing to receive the booster dose may opt to use the same brand of vaccine or a brand different from what they received in the primary series. Here’s a list of the DOH’s recommended interval and booster dose combinations:

Sinovac