What to know about ‘bivalent vaccines’ that target Omicron

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MANILA, Philippines—As countries like the Philippines continue to administer primary and booster doses of vaccines against COVID, the United States (US) and United Kingdom (UK) will soon roll out a new tool against the virus: updated booster shots targeting a particular sub-variant.

Last week, the US Food and Drug Administration (FDA) and the US Centers for Disease Control and Prevention (CDC) have authorized the updated COVID booster shots—also called “bivalent vaccines” by Pfizer-BioNTech and Moderna.

READ: U.S. FDA okays two COVID boosters targeted at Omicron subvariants

While the current vaccines against COVID still provide protection against the disease and its most severe outcomes, the updated booster shots target the original strain of SARS-CoV-2 virus and the more contagious Omicron sub-variant.

The European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) and Health Canada have also approved both the PfizerBioNTech and Moderna bivalent shots.

READ:  EU regulator backs Omicron-adapted COVID shots

As early as December 2021, pharmaceutical companies that manufacture and distribute the current vaccines being used in the Philippines and other countries across the globe—Pfizer-BioNTech, Moderna, AstraZeneca, Sinovac, and Sinopharm—have been suggesting and discussing the possibility of a new vaccine dose against the latest COVID sub-variants.

Prior to the US, UK, and Canada’s decision to authorize the bivalent vaccine, in the Philippines, President Ferdinand “Bongbong” Marcos Jr. said the government will look into the Omicron-targeting vaccine.

“I was just told by Health Undersecretary Ma. Rosario Vergeire that there will be a vaccine against the new sub-variants of Omicron,” the President said during the PinasLakas vaccination campaign in Manila last August 17.

“We will study this, and if it is going to be helpful, then we will do everything to bring it here to the Philippines, and we can give it to those who need to receive the booster shot.”

READ: Marcos gov’t looks into COVID-19 vaccine targeting Omicron variant

With the rollout of updated boosters expected within days in the US, UK, and Canada, here are things Filipinos should know about the Omicron-targeted vaccines.

Updated boosters, bivalent shots, what is it?

The updated vaccines contain a genetic recipe that can detect and fight both the original strain of the SARS-CoV-2 virus and Omicron sub-variants BA.4 and BA.5.

According to the US FDA, “[t]he authorized bivalent COVID-19 vaccines, or updated boosters, include an mRNA component of the original strain to provide an immune response that is broadly protective against COVID-19 and an mRNA component in common between the omicron variant BA.4 and BA.5 lineages to provide better protection against COVID-19 caused by the Omicron variant.”

GRAPHIC Ed Lustan

The BA.4 and BA.5 lineages of the Omicron variant are currently the culprit behind most cast cases of COVID-19 in the US. Health experts said cases due to the said sub-variants might increase this fall and winter.

In the Philippines, as of August 16, the Department of Health (DOH) has recorded a total of 5,214 cases of infection with BA.5 Omicron sub-variant and 168 cases of BA.4 Omicron sub-variant.

READ: DOH records 1,011 more cases of BA.5 Omicron subvariant

“We deliberately picked BA.4 or 5,” Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research—which oversees vaccines, said last August 31 when asked why the updated shots specifically target the two Omicron sub-variants.

GRAPHIC Ed Lustan

During the massive surge in cases of BA.1 in the US earlier this year, both Pfizer-BioNTech and Moderna have tested vaccines based on the sub-variant. However, BA.1 was soon found to be no longer circulating in the country.

Last June, the US FDA asked vaccine manufacturers to develop a booster specifically targeting the Omicron BA.4 and BA.5 sub-variants.

“This gives us a variant that is most up-to-date, and most likely looks closer to something that may evolve further in the fall,” said Marks. “The more up-to-date you are, the better chance we have of [the vaccine] working for what comes afterward.”

Available doses: Who can get it?

Currently, there are four vaccine manufacturers that have developed bivalent vaccines against the highly contagious Omicron sub-variants. These include Pfizer-BioNTech, Moderna, Sinovac, and Sinopharm’s subsidiary China National Biotec Group (CNBG).

As of April, Sinovac and Sinopharm’s Omicron-specific vaccines were able to secure approvals for human clinical trials in Hong Kong.

READ: Omicron-specific Sinopharm, Sinovac vaccine candidates cleared for clinical trial

READ: Chinese-made Omicron vaccine trials get going

Pfizer-BioNTech’s Comirnaty Bivalent Original/Omicron BA.4/BA.5 vaccine, and Moderna’s Spikevax Bivalent Original/Omicron BA.4/BA.5 were authorized by the US FDA and US CDC for use as a single booster dose for certain individuals.

According to US FDA’s guidelines, Moderna’s bivalent vaccine is authorized for use as a single dose in individuals 18 years and older—if it has been at least two months since they have completed primary vaccination or have received the most recent booster dose with any authorized or approved monovalent COVID-19 vaccine.

Pfizer-BioNTech’s bivalent vaccine, on the other hand, is authorized for use as a single booster dose in individuals 12 years of age and older—if it has been at least two months since they have completed primary vaccination or have received the most recent booster dose with any authorized or approved monovalent COVID-19 vaccine.

GRAPHIC Ed Lustan

“The COVID-19 vaccines, including boosters, continue to save countless lives and prevent the most serious outcomes (hospitalization and death) of COVID-19,” said FDA Commissioner Robert M. Califf.

“As we head into fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against currently circulating variants.”

The European Union’s drug regulator, meanwhile, authorized the use of Pfizer-BioNTech’s Comirnaty Original/Omicron BA.1 and Moderna’s Spikevax bivalent Original/Omicron BA.1. Health Canada authorized only the latter version.

Although the authorized updated booster shots in UK and Canada are not the same as the ones approved in the US—in a sense that they specifically target only the B1 Omicron sub-variant—clinical trials found that they were also effective in combatting the BA.4 and BA.5 sub-variants.

According to clinical trial results, this is due to the spike protein in BA.1, which can also be found in BA.4 and BA.5.

Half of the updated booster shots to be used in the US is made up of the mRNA codes for the spike protein of the virus that originally emerged in Wuhan, China in 2019. The other half codes for the spike protein in BA.1.

“Clinical trial results showed that a booster dose of the bivalent Moderna Spikevax vaccine triggers a strong immune response against both Omicron (BA.1) and the original SARS-CoV-2 virus strain,” Health Canada said in a statement.

“It was also found to generate a good immune response against the Omicron BA.4 and BA.5 sub-variants, and is expected to extend the durability of protection,” it added.

Rollout soon, but…

As the US awaits doses of the BA.4-BA.5 vaccines, some health experts have raised concerns regarding the new boosters.

Pfizer-BioNTech and Moderna were originally developing new boosters focusing on the first Omicron sub-variant, BA.1. Up until June—when the US FDA requested to switch gears and target BA.5 sub-variant instead—human clinical trials showed promising results despite some side effects similar to those of the original vaccines.

READ: Moderna begins trial of Omicron-specific vaccine booster

Both companies, however, did not have enough time to conduct human clinical trials for the BA.4-BA.5 boosters due to abrupt changes made by the US FDA. Instead, Pfizer and Moderna submitted animal and lab data for the new booster shots.

“They have not released those data publicly, although at the June FDA meeting, Pfizer presented preliminary findings in eight mice given BA.4/BA.5 vaccines as their third dose,” an article published in Science—the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS)—stated.

“Compared with the mice that received the original vaccine as a booster, the animals showed an increased response to all Omicron variants tested: BA.1, BA.2, BA.2.12.1, BA.4, and BA.5.”

According to the companies, clinical trials for the BA.4-BA.5 vaccines will begin next month.

The companies need to secure full approval for their updated vaccines—their recent submissions and approval from the US FDA were only for emergency use authorization (EUA).

Several members of the CDC’s independent advisory committee, however, expressed reservations about the boosters’ lack of human data.

“There’s a lot of vaccine hesitancy already — we need the human data,” said Pablo Sanchez, a professor of pediatrics at Ohio State University and the only CDC committee member who voted against the authorization of the BA.4-BA.5 boosters.

Is it safe?

Despite concerns due to lack of human data, health officials maintain that the bivalent vaccines are safe and that granting EUA for vaccines even with data only from lab and animal trials is something that has already been done before.

Using animal and lab data to solicit regulatory approval for retooled vaccines is not without precedent, it is done regularly for flu vaccines that are revamped each year to combat new variants.

“We’re pretty confident that what we have is very similar to the situation that we’ve done in the past with influenza changes where we don’t do clinical studies for them in the United States,” said Marks.

“We know from the way the vaccine works, and from the data that we have, that we can predict how well the vaccine will be working.”

According to the US FDA, the EUAs for Pfizer-BioNTech and Moderna’s bivalent vaccines were based on earlier human trials for the BA.1 Omicron vaccines.

“Based on the data supporting each of these authorizations, the bivalent COVID-19 vaccines are expected to provide increased protection against the currently circulating omicron variant.”

“The agency will work quickly to evaluate future data and submissions to support authorization of bivalent COVID-19 boosters for additional age groups as we receive them.”

CDC Director Rochelle P. Walensky urged the public to get the updated boosters as these help provide increased protection against COVID-19 disease and death.

“The updated COVID-19 boosters are formulated to better protect against the most recently circulating COVID-19 variant. They can help restore protection that has waned since previous vaccination and were designed to provide broader protection against newer variants,” Walensky said in a statement.

“This recommendation followed a comprehensive scientific evaluation and robust scientific discussion. If you are eligible, there is no bad time to get your COVID-19 booster and I strongly encourage you to receive it,” she added.

Vaccine status in PH

While clinical human trials and rollout of the bivalent vaccines are underway overseas, the Philippines continues to inoculate its population.

GRAPHIC Ed Lustan

Data as of September 4 showed that a total of 160,946,965 vaccine doses for CVID-19 have been administered nationwide.

At least 70,131,973 individuals have already received their first dose, 72,620,347 have been inoculated with second dose, and at least 18,194,645 already had their booster dose.

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