Pfizer’s Omicron-Adapted Candidate Vaccines Show Positive Results

Pfizer and BioNTech have announced positive safety, tolerability and immunogenicity data for two Omicron-adapted COVID-19 mRNA candidate vaccines – but for an earlier strain of Omicron than those that are currently globally dominant. 

The two Omicron-adapted vaccine candidates were given to 1,234 participants aged 56 years and older as boosters, and “elicited substantially higher neutralizing antibody responses against Omicron BA.1 when compared to the companies’ current COVID-19 vaccine,” according to the announcement. 

The monovalent vaccine candidate, which was designed to immunize against a single antigen, elicited a 13.5- and 19.6-fold increase in neutralizing titers against Omicron BA.1, Pfizer said in its release. 

The bivalent candidate, which is a combination of the traditional Pfizer vaccine and a vaccine targeting the spike protein of BA.1, exhibited a 9.1- and a 10.9-fold increase against Omicron.

However, the dominant strains of Omicron worldwide are currently BA.4 and BA.5. Preliminary laboratory studies show that the candidates neutralize BA.4 and BA.5, but to a lesser extent.

“Omicron has newly evolving sublineages that have outcompeted BA.1 and exhibit a trend of increasing potential for immune escape,” explained Prof Ugur Sahin, CEO of BioNTech. “We will therefore remain vigilant and are prepared to rapidly adapt our Omicron-adapted vaccine candidates to emerging sublineages if epidemiological and laboratory data suggest.”

Meeting with FDA

The companies will submit the results and discuss them with the US Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee on 28 June and with the International Coalition of Medicines Regulatory Authorities on 30 June.

“Based on these data, we believe we have two very strong Omicron-adapted candidates that elicit a substantially higher immune response against Omicron than we’ve seen to date,” said Pfizer CEO Albert Bourla. “We look forward to discussing these data with the scientific community and health authorities so we may rapidly introduce an Omicron-adapted booster as soon as possible if authorized by regulators.”

The vaccines were also shown to be safe and have no additional side effects than the original vaccine.

Moderna Omicron vaccine also shown effective

Earlier this month, Moderna announced that it too had an updated COVID-19 booster shot that is more effective against stopping Omicron infection than its original jab. 

“We are thrilled to share the preliminary data analysis on mRNA-1273.214, which is the second demonstration of superiority of our bivalent booster platform against variants of concern and represents an innovation in the fight against COVID,” Moderna CEO Stéphane Bancel said in a company news release.

“Looking at these data alongside the durability we saw with our first bivalent booster candidate, mRNA-1273.211, we anticipate more durable protection against variants of concern with mRNA-1273.214, making it our lead candidate for a fall 2022 booster,” Bancel continued. “We are submitting our preliminary data and analysis to regulators with the hope that the omicron-containing bivalent booster will be available in the late summer.”

Like Pfizer, the company did not yet have any firm data on the vaccine’s effectiveness against BA.4 and BA.5.

Cases on the rise 

The Omicron variant was first spotted in Botswana and labeled as a variant of concern in April. BA.4 and BA.5 are its newest mutations and have been spotted in dozens of countries worldwide, causing a surge in cases because they can spread faster than other circulating variants.

On some days, more than 730,000 new daily COVID-19 cases are being reported daily, according to World O Meters – with more than 4.2 million reported in the last seven days.

The country with the highest number of new daily cases is the United States, followed by Germany and Brazil.


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