Vaccine Studies Should Have Transmission Rate Data: Marks
CBER director Peter Marks says that in an ideal world vaccine clinical trial designs should evaluate the investigational vaccine’s effect on disease transmission. Having such data, particularly if the vaccine has a decent effect against transmission, would be beneficial in today’s age of growing vaccine hesitancy after the Covid-19 health emergency, he says, adding that such evidence helps when deploying a new vaccine.
Speaking at a 3/20 Duke Margolis Institute for Health Policy virtual program on generating evidence on the indirect benefits of infectious disease products, Marks said that for certain infectious diseases, vaccines do a very good job at preventing transmission. For example, the older pertussis vaccine both prevented disease and prevented the transmission of the infectious agent. However, he pointed out, while the first generation of Covid-19 vaccines saw an up to 50% reduction in transmission, “subsequently that fell off practically to zero or close to it. So we have this desire to try to have a combination of, ideally, direct benefit and indirect benefit baked into the vaccines.”
The trouble with designing vaccine trials to evaluate disease transmission is that it can be expensive to get the data. Marks said it’s also “much easier to look at individual surrogates of protection, or correlates of protection, such as antibody levels in an individual, or the prevention of disease in a given individual, than in a household context, etc. When this was suggested, for instance, during Covid-19, that a study be done that would formally look at the interruption of transmission, the cost became just insurmountable.
“So unless you had a particular population that you could use that was at risk, for instance, college students or those in the military population in a given closed location, it’s very hard to imagine that,” Marks continued. “But I think as we move forward, we need to think about generating this kind of evidence because we are going to need compelling evidence to help people feel convinced that vaccination is good for themselves, but also for their communities. And having that kind of information may be helpful.”
Marks said without compelling evidence of safety and vaccine effectiveness for the individual and potentially for the community, the U.S. will face significant mortality numbers if and when the next public health emergency arrives. After experiencing Covid-19, Marks recognizes that vaccine mandates are not the solution that will get the country to the other side of an emergency, rather it will be compelling evidence.
“Now it's up to people much smarter than me about how we’re going to end up communicating through some layers that would seem to not want to accept that vaccination is the public health triumph that it is,” he said. In a presumably subtle recognition of the new HHS leadership’s view on vaccines, Marks ended his discussion on this by saying he would like to come back to his desk the next morning.