"The study will evaluate up to 1,420 participants across the three cohorts:
"Cohort #1 (n = 615): Received two doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; in the study, participants will receive one or two doses of the Omicron-based vaccine
"Cohort #2 (n = 600): Received three doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; in the study, participants will receive one dose of the current Pfizer-BioNTech COVID-19 vaccine or the Omicron-based vaccine
"Cohort #3 (n=205): Vaccine-naïve participants will receive three doses of the Omicron-based vaccine"
I realize that we are dealing with different strains and that coronaviruses never generated much permanent immunity, but the idea that an actual viral infection does not result in immunity as (or more) effective as a vaccine goes against my clinical expectations. I thought that reinfection rates have remained fairly low despite shifts in SARS-CoV-2 strains. Is it possible that, when we study vaccine effectiveness, we are measuring immunity to Delta or Omicron in a fairly specific or limited way, thus missing other ways in which an actual infection might generate immunity? Should we perhaps be calling it "measurable Omicron immunity" instead?
Pfizer just announced that they're starting their Omicron vaccine trial: https://investors.pfizer.com/Investors/News/news-details/2022/Pfizer-and-BioNTech-Initiate-Study-to-Evaluate-Omicron-Based-COVID-19-Vaccine-in-Adults-18-to-55-Years-of-Age/default.aspx. From the press release:
"The study will evaluate up to 1,420 participants across the three cohorts:
"Cohort #1 (n = 615): Received two doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; in the study, participants will receive one or two doses of the Omicron-based vaccine
"Cohort #2 (n = 600): Received three doses of the current Pfizer-BioNTech COVID-19 vaccine 90-180 days prior to enrollment; in the study, participants will receive one dose of the current Pfizer-BioNTech COVID-19 vaccine or the Omicron-based vaccine
"Cohort #3 (n=205): Vaccine-naïve participants will receive three doses of the Omicron-based vaccine"
I realize that we are dealing with different strains and that coronaviruses never generated much permanent immunity, but the idea that an actual viral infection does not result in immunity as (or more) effective as a vaccine goes against my clinical expectations. I thought that reinfection rates have remained fairly low despite shifts in SARS-CoV-2 strains. Is it possible that, when we study vaccine effectiveness, we are measuring immunity to Delta or Omicron in a fairly specific or limited way, thus missing other ways in which an actual infection might generate immunity? Should we perhaps be calling it "measurable Omicron immunity" instead?