Pfizer-BioNTech Begin Studies on Omicron-Based COVID-19 Vaccines

Pfizer and BioNTech announced today they have begun a clinical study looking at their Omicron-Based COVID-19 vaccine.

“Vaccines continue to offer strong protection against severe disease caused by Omicron,” BioNTech CEO and Cofounder Ugur Sahin said. “Yet, emerging data indicate vaccine-induced protection against infection and mild to moderate disease wanes more rapidly than was observed with prior strains.”

The trial will look at 3 groups and study up to 1420 people.

The cohorts include:

• Cohort #1 (n = 615): These participants will have received 2 doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; participants will receive 1 or 2 doses of the Omicron-based vaccine
• Cohort #2 (n = 600): Received 3 doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; in the study, participants will receive 1 dose of the current Pfizer-BioNTech COVID-19 vaccine or the Omicron-based vaccine.
• Cohort #3 (n=205): Participants who will receive 3 doses of the Omicron-based vaccine.

Studies are showing mixed results with the booster doses. They are affording some level of protection, but not at the levels previously seen. In a study done in Israel, health care workers who received a Pfizer-BioNTech COVID-19 vaccine booster dose were significantly less likely to contract SARS-CoV-2 than those who received 2 doses.

Participants in the study had previously received a 2-dose series of the Pfizer-BioNTech COVID-19 vaccine at least 1 month before study enrollment, and 1650 (85.6%) received a booster dose.

During the study, 44 participants contracted COVID-19, including 39 who hadn’t received the booster dose and 5 who had, for an incident rate of 116 per 100,000 person-days compared with 12.8. Compared with those who only received two doses of the vaccine, the adjusted hazard ratio for SARS-CoV-2 infection after booster was 0.07 (95% CI, 0.02-0.20). Of the infections, 31 (70.5%) were symptomatic and 13 (29.5%) were asymptomatic.

Also the study showed those who were not administered a booster dose were more likely to be symptomatic than those among boosted participants (71.7% compared with 60% respectively).

Conversely, another study done in Israel administered a fourth dose of the Pfizer-BioNTech COVID-19 vaccine demonstrated it did raise antibodies but was only partially efficacious against the Omicron variant.

Still, the world is trying to find out the best strategy for looking at vaccines going forward. There has been talk of periodical vaccines including an annual vaccine given like the current influenza vaccines.

"This study is part of our science-based approach to develop a variant-based vaccine that achieves a similar level of protection against Omicron as it did with earlier variants but with longer duration of protection,” Sahin added.