It looks like there’s more good news from the Israeli studies analyzing the effectiveness of the Pfizer-BioNTech vaccine. Pfizer recently reported that, two weeks after the second dose, not only is the vaccine 97% effective against symptomatic illness, hospitalizations, and deaths, but it also appears to be 94% effective against asymptomatic infections. (Pfizer Press Release: “Real-World Evidence Confirms High Effectiveness of Pfizer-BioNTech Covid019 Vaccine…”).
Asymptomatic carriers are those people who are infected with coronavirus but do not exhibit any symptoms (i.e. – they do not have fevers, sore throats, coughing, etc.). These people may end up unknowingly spreading it to others. In fact, the data suggests this happens quite a bit, as “transmission from asymptomatic individuals was estimated to account for more than half of all transmission.”(See JAMA Article: SARS-CoV-2 Transmission from People Without COVID-19 Symptoms) (emphasis added).
There was some question as to whether developed vaccines like Pfizer-BioNTech’s would be effective against asymptomatic carriers. We knew, based on preliminary analyses and clinical trials, that the vaccine (and Moderna’s) was extraordinarily effective at preventing severe disease, hospitalizations, and death. But only recently has this new data suggested that the vaccine protects against less severe/asymptomatic disease.
This is an extremely important finding, as it indicates this vaccine will have a significant effect in reducing transmission and stopping the spread. As always, more data and peer review are needed to better estimate the effectiveness in curbing transmission (particularly regarding other vaccines). Nonetheless, this is welcoming news—and timely news—given that we have now passed the one year mark since the pandemic was declared. At the same time, people should remain vigilant and continue following federal/state/city guidelines regarding social distancing, masking, and good hygiene practices.