Influenza Vaccine's Efficacy Far From Perfect

The findings of the meta-analysis and the CIDRAP report are generally correct, but they aren’t new. We all know that influenza vaccine is a good vaccine, but far from a perfect vaccine. We’ve always known about the limitations of flu vaccine and the limitations of the data in various age groups, particularly in older persons. But I think there are ample data to show some efficacy of the vaccine. Some people don’t get sick, some get milder illness, and we do prevent deaths and hospitalizations (which was not addressed in the CIDRAP paper). Do we prevent them all? No. But preventing some is a very good thing.

I don’t agree with the exclusion of studies that used serologic end points. I think that there are many people who would not simply throw out all those studies, and would say that although they’re not perfect, they have merit if you add them all together, and they all point in the same direction, and they provide information that’s consistent with other studies. The objective should be to interpret the entirety of the evidence.

The recent pace of vaccine advances should also be acknowledged. The last 5 years have seen more research aimed at producing better influenza vaccines than there had been in the previous 40 years. Indeed, Fluzone High-Dose vaccine, which is much more immunogenic than the older TIV, has recently been approved for adults aged 65 and older. Efficacy studies of that vaccine are ongoing. In addition, both adjuvanted vaccines and cell-based influenza vaccines have already been approved in Europe and are expected to receive U.S. licensure soon. The last few years have just opened up the spigot on flu vaccine research. There’s a lot of it going on.

William Schaffner, M.D., is professor and chair of preventive medicine and professor of medicine at Vanderbilt University in Nashville, Tenn., serves on the data safety monitoring board for Sanofi-Pasteur and Merck, and is an occasional consultant for Novartis, GlaxoSmithKline, and Pfizer.