Last week Pfizer/BioNTech declared that its coronavirus vaccine will protect people for around six months following the second dose. But it did lower its effectiveness level from 95%, declared in November 2020, to 91% . That modification doesn’t surprise Carlos Malvestutto, MD, an infectious disease expert at The Ohio State University Wexner Medical Center. Real world effectiveness is generally lower than clinical trial efficacy in many cases because clinical trial participants are a chosen population of motivated people , he explained.
Dr. Malvestutto took the time to answer a few questions for Medical Daily.
Q. Why would the consequences of a real-world study be so far away from people in a controlled trial, in which 10s of thousands of people were participating ?
A. real-world effectiveness is generally lower than clinical trial efficacy in many instances because clinical trial participants are a selected population of motivated individuals . The results of the observational study in health-care employees are not very far away from the randomized clinical trial vaccine efficacy estimates. You have to take into account the wide confidence intervals of these estimates [68%-97%) for full vaccination and 59-90%) for partial vaccination, so the actual efficacy falls somewhere within those confidence intervals. To me, these real-world efficacy trials confirm the high vaccine efficacy reported in the clinical trials.
Q. Do these results surprise you?
A. Not at all. These results are consistent with the exceptional vaccine efficacy in the large phase 3 clinical trials for the Pfizer and Moderna/BioNTech vaccines. it’s also very encouraging to find that partial immunization can provide a very large level of protection. Other observational studies are also always showing high levels of efficacy in most populations.
Q. The study was conducted from December to March, during which time the variations were out there. Does that fact implies that the mRNA system is even better than what the research results are?
A. We are aware that the clinical trials were conducted before the B1.117 along with other variants of concerns were beginning to circulate in the U.S. This study will be doing genomic sequencing of the virus to determine the prevalence of the variants but we can assume that at least a substantial percentage of these cases in this study were due to the B1.117 and other new variations which strengthens the conclusion that these vaccines are highly effective even in the presence of these new variants .
Q. There don’t appear to be any similar studies regarding the J&J vaccine. Would you anticipate that vaccine to have similar effectiveness in a real world setting?
A. We will finally see similar studies for the J&J vaccine. It received Emergency Use Authorization last month and it has just recently begun to be administered so there wouldn’t be enough individuals vaccinated with this vaccine yet to do a real-world efficacy research . I am positive that we will have similar data on this vaccine in the long run .
Carlos Malvestutto, MD, is an infectious disease specialist at The Ohio State University Wexner Medical Center. Ohio State University
Carlos Malvestutto, MD, an infectious disease specialist at The Ohio State University Wexner Medical Center.