Pfizer announced on Saturday that its tweaked COVID-19 vaccines meant to target the Omicron variant are safe and effective and deliver a “substantially higher immune response” against the highly transmissible strain.
The company, along with its partner BioNTech, made the announcement as the FDA considers ordering an updated vaccine from both Pfizer and Moderna in the hopes that modified boosters can better protect against the anticipated surge in cases come fall and winter.
The company tested two types of vaccines: one that is monovalent, meaning that it specifically and solely targets omicron, and another that is bivalent, which combines the monovalent vaccine with the company’s existing vaccine that targets the original COVID-19 strain. The company also tested different dosage amounts, seeing whether to keep the current 30 micrograms dose or to double it.
According to the data collected by the companies, studies “found that a booster dose of both Omicron-adapted vaccine candidates elicited a substantially higher immune response against Omicron BA.1 as compared to the companies’ current COVID-19 vaccine.”
The study looked at 1,234 adults over the age of 56 who already had three doses of the vaccine. Researchers saw an increase in protection against the Omicron variant in both the monovalent and bivalent vaccine groups, and the higher dosage of 60 micrograms was found to offer more protection.
“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,” Albert Bourla, Chairman and Chief Executive Officer of Pfizer, said in a press release. “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 Omicron-only booster saw a 13.5- and 19.6-fold increase in neutralizing the virus, while the bivalent vaccine exhibited a 9.1- and 10.9-fold increase in protection against Omicron. Even though the monovalent vaccine appears to offer the highest protection, many experts believe combination shots are the best way to go, as they keep up protections against the original strain and still up Omicron-fighting antibodies.
On June 30, the FDA’s scientific advisers will discuss the data as they decide whether or not to recommend a new recipe for the vaccines.