The Great Promise of a One-Dose Vaccine
The U.S. Food and Drug Administration’s expert advisory committee is meeting today to discuss the emergency use authorization of Johnson & Johnson’s Covid-19 vaccine. If authorized, it will be the first single-dose Covid-19 vaccine. Despite some confusing data about its efficacy compared with other vaccines, this new one-shot vaccine has the potential to substantially ease the logistical problems that we’ve seen to date. Healthcare systems, especially in the 130 countries that have yet to give out their first shots, should pay close attention. Americans should, too. First, consider the efficacy issue. Compared to the eye-popping 95% efficacy levels of the two-dose Moderna and Pfizer vaccines, Johnson & Johnson’s 66% efficacy at preventing moderate and severe disease might seem disappointing. But it is important to realize that 66% is a very high efficacy level in absolute terms.