COVID-19 vaccine recipients may need booster shots amid new variants: expert

Kristine Sabillo, ABS-CBN News

Posted at Mar 25 2021 01:33 PM | Updated as of Mar 25 2021 04:53 PM

Video courtesy of the Philippine Medical Association

MANILA — COVID-19 vaccine recipients may need booster shots to give added protection against variants of concern, vaccine experts said Thursday. 

“I actually foresee that happening. After 'yung primary series na tinatawag natin 'yung 2 doses nitong Sinovac or AstraZeneca or itong incoming vaccines, we need another dose or a booster shot,” Dr. Nina Gloriani, who heads the country’s vaccine expert panel (VEP) for COVID-19 vaccines, said at a forum organized by the Philippine Medical Association, the Philippine Foundation for Vaccination and the Pharmaceutical & Healthcare Association of the Philippines.

(I actually foresee that happening. After what we call the primary series — the 2 doses of Sinovac or AstraZeneca or any of the incoming vaccines, we need another dose or a booster shot).

Gloriani said the booster shot “may not be the original one (vaccine) but something that may cover the variants as well.”

Multivalent COVID-19 vaccines or those made to immunize against two or more variants will be needed in the future, she said. 

Experts have previously explained that while most variants are harmless, there are some that may cause the virus to be more transmissible or have an effect on the immune system.

Dr. Lulu Bravo, a vaccine advocate who now heads the National Adverse Events Following Immunization Committee (NAEFIC), said COVID-19 vaccines will probably be like flu vaccines, which are given ever year and contain antigens for different strains.

“As time goes by we do not know yet how many variants we will have. It will be quite difficult to treat and therefore has to be included in the vaccine,” she said.

Gloriani said flu vaccines are currently based on biosurveillance data.

“Nakikita natin ano 'yung nagcicirculate na strains o serotypes during the last year or two. 'Yun ang nagiging basehan for the new vaccines,” she said.

(We see what the circulating strains or serotypes are during the last year or two. And that is the basis for the new vaccines.)

Gloriani said that for COVID-19 there are only 3 variants of concern right now — the B.1.1.7 first detected in the United Kingdom, the B.1.351 detected in South Africa and the P.1 detected in Brazil.

As of Wednesday, there are 223 UK variant cases in the Philippines, 152 South African variant cases and 1 Brazil variant detected in a returning overseas Filipino.

“I foresee that the 2nd generation vaccines will contain these variants, 'yung antigens corresponding to the variants,” she said.

A cause of concern in particular is the E484K mutation, which is said to enable the virus to “escape” the body’s immune system. The said mutation is found in both the South African and the Brazil variant. 

Gloriani said that some vaccine developers are already studying how the variants of concern affect vaccine efficacy.

She said the Novavax COVID-19 vaccine was 96% efficacious in a trial one in the United Kingdom but when it was tested in South Africa against the South African variant, the vaccine efficacy went down to 60%. It went further down to 49.3% for those with HIV infection.

“The same is true with Jansen - Johnson and Johnson, which is another platform. The vaccine efficacy in US trials was 74%. With the Brazil variant, it was 66%. With the South African variant it was 52%,” she said.

While there are no efficacy rates yet for Pfizer and Moderna, both vaccines were said to have shown lesser efficacy although they reportedly still provide adequate protection.

For AstraZeneca’s vaccine, which has an efficacy rate of 75% to 84%, a small study involving 2,000 people showed only 10% efficacy.

Like the World Health Organization, Gloriani explained that the study is small compared to the other vaccines and more information is needed. 

She also explained that vaccines should not be compared based on their efficacy rates since their clinical trials involve different populations. Some may have had more variant cases than others.

There are now more than 500,000 people in the Philippines vaccinated with COVID-19 vaccines from Sinovac or AstraZeneca. 

“Even amid the variants we still need to vaccinate. That is our only hope. I always say, we are racing against time here. The sooner we vaccinate the 70 to 80 percent we need for herd immunity, the better for us,” she explained.

Asked if vaccine developers can catch up with the variants, she said, “Hindi madali. Complicated talaga itong pandemic na ito, the virus itself, but we have to try.”

(It’s not easy. This pandemic is complicated. The virus too. But we have to try.)

Gloriani said what is needed now is the cooperation of everyone - to follow minimum health protocols - in order to curb the spread of the disease and the emergence of more harmful variants.