Vaccine Effectiveness: 90% vs 44%

Some traders were confused by the market’s volcanic response to yesterday’s news that Pfizer has a covid vaccine with 90% effectiveness. Well, as DB’s Jim Reid explains today, “it’s easy to see why there is so much excitement over Pfizer’s news yesterday. When we compare the average 10 year effectiveness of the flu vaccine (44%) with vaccines for other diseases it falls well short and expectations were benchmarked around trying to beat this rather than compete with the most successful vaccines.”

However, the early Pfizer number – which one must take with a ton of salt as it appeared not in a peer reviewed journal but in a corporate press release, and was oddly timed to hit just after the election – puts the vaccine effectiveness up there with that seen for Chickenpox, Mumps, Polio and Whooping Cough, which as Reid notes, is “a long way to go but very encouraging.”

Or said otherwise, of the 94 cases of covid contracted by participants in the Pfizer study, 86 occurred in the control group. If you tossed a coin 94 times, the chances of getting 86 or more heads is infinitesimally small so its safe to say the vaccine works.

Of course, Pfizer is just one of many companies rushing to come to market with a working vaccine (whether the population will voluntarily take it is an other matter entirely). However, one thing is certain: as vaccine news permeates over the coming weeks and months the world will move on to discussing how to rebuild the world post covid; in this context any future push by administrations to enforce more mandatory quarantines and shutdowns will not be greeted well by the broader population.