Moderna testing 3 COVID-19 booster vaccines on omicron variant, Pfizer ready to adapt

COVID-19 has given rise to many variants in the last two years, but none have so far managed to evade the authorized vaccines that have been administered to millions around the world. Should that ever change, Pfizer and Moderna said they stand ready to act. 

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The emergence of the omicron variant has renewed fears of the novel coronavirus acquiring mutations that would allow it to evade existing vaccines. Scientists in South Africa announced the new variant’s discovery this week and said it shows several mutations and clues it could be highly infectious.

An advisory panel of the World Health Organization on Friday classified the worrying new variant as a highly transmissible virus of concern, naming it "omicron" under its Greek-letter system.

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The U.N. health agency also said early evidence on the variant, until now known by the technical term B.1.1.529, has shown an increased risk of reinfection compared to other highly transmissible variants, indicating that people who contracted COVID-19 and recovered could be more subject to catching it again with omicron. 

The WHO suggested that the variant could pose greater risks than the delta variant, which was first detected in India and has been ravaging countries worldwide.

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The advisory group faced spiraling worries about the variant, as stock markets plunged and the European Union announced a pause to flights to and from southern Africa, just as it sought to lay out the real threat that it might pose even as uncertainties and a lack of complete data about it remain in its early phase.

"We understand that people are concerned," said Maria Van Kerkhove, the WHO’s technical lead on COVID-19, in a video statement provided by the agency. "The good thing is that we have a monitoring system around the world to detect these variants."


An illustrative image of a person holding a medical syringe and a vaccine vial in front of the Pfizer logo displayed on a screen. On Thursday, October 21, 2021, in Edmonton, Alberta, Canada. (Photo by Artur Widak/NurPhoto via Getty Images)On Thursday

She noted that omicron has a large number of mutations, and has said it will take weeks before scientists can assess its possible effect on vaccines, for example.

After news of the burgeoning omicron variant triggered travel bans around the world Friday, Moderna announced that it is testing several current booster vaccine candidates against the variant and developing a booster dose meant to target omicron specifically.

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"The Moderna COVID-19 vaccine is authorized as a booster for many populations at the 50 µg dose level. The Company is working rapidly to test the ability of the current vaccine dose to neutralize the Omicron variant and data is expected in the coming weeks," Moderna wrote in its announcement.

The company’s strategy includes testing three existing COVID-19 vaccine booster candidates against the omicron variant, should the currently authorized 50 µg booster dose of mRNA-1273 prove insufficient to boost waning immunity.

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Moderna has already tested a higher dose booster of mRNA-1273 in healthy adults, and is already studying two multi-valent booster candidates in the clinic that were designed to anticipate mutations such as those that have emerged in the omicron variant.

Additionally, Moderna said it will rapidly advance an omicron-specific booster candidate (mRNA-1273.529).

"From the beginning, we have said that as we seek to defeat the pandemic, it is imperative that we are proactive as the virus evolves. The mutations in the Omicron variant are concerning and for several days, we have been moving as fast as possible to execute our strategy to address this variant," said Stéphane Bancel, chief executive officer of Moderna. 

"We have three lines of defense that we are advancing in parallel: we have already evaluated a higher dose booster of mRNA-1273 (100 µg), second, we are already studying two multi-valent booster candidates in the clinic that were designed to anticipate mutations such as those that have emerged in the Omicron variant and data is expected in the coming weeks, and third, we are rapidly advancing a Omicron-specific booster candidate (mRNA-1273.529)," Bancel said.

Pfizer, meanwhile, said if a variant ever evades the protection offered by its FDA-approved COVID-19 vaccine Comirnaty, it expects to be able to produce a "tailor-made" vaccine against that variant in approximately 100 days, pending approval from federal regulators.

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"Pfizer and BioNTech are remaining vigilant, and we are constantly conducting surveillance efforts focused on monitoring for emerging variants that potentially escape protection from our vaccine. As always, we will continue to follow the science as we examine the best approaches to protecting people against COVID-19.

It’s too soon to know how infectious the omicron variant is and how well the vaccine protects against it. South Africa, the country with the most cases of that variant, has only a small percentage of its population vaccinated. And researchers haven’t had enough time to learn all the risks posed by the variant.

The last variant to cause international concern was delta. It proved able to cause a high number of breakthrough infections, which happen when a fully-vaccinated person contracts the virus.

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The WHO announcement marks the first time in months that it has classified a COVID-19 variant as the highly-transmissible "variant of concern." The classification also applies to delta, which has become the world’s most prevalent variant. It comes amid a surge in cases of delta in Europe in particular, and at a time when many countries had eased lockdown measures and travel restrictions.

Variants of concern, which include alpha, beta and delta, have shown to spread more easily, cause more serious disease, or dent the effectiveness of vaccines and other COVID-fighting tools. They’re more worrying than the so-called variants of interest — like mu and lambda — that have affected aspects like transmissibility and severity of the disease but aren't as transmissible.

Still, breakthrough patients endured illnesses far milder than their unvaccinated counterparts. The vaccines remained highly effective at preventing severe illness and death.

This story was reported from Atlanta. The Associated Press contributed..