With the phrasing of the FDA authorization, it seems that this will be an individual decision between a patient and their medical team, balancing the risk of the third dose, such as risk of rejection in organ transplant patients, versus the benefits. It is also possible to use antibody levels as a surrogate for how much immune protection the patient had, and to include the results of these tests as part of the clinical decision-making.

There is evidence emerging that immunity after vaccinations might wane slightly over time and also that some patient groups might just not develop immunity from the usual vaccine doses. Because of this, there is a lot of interest in boosters for both certain patient cohorts, such as immune suppressed patients with an organ transplant or on cancer therapy, as well as the larger community—in particular, more vulnerable members, such as the very elderly. Next there will be discussions about boosters for health care workers because they have the highest risk of exposures working at front lines and then, finally, the general population. All these decisions should keep in mind health equity issues among populations within the U.S. as well as globally, as some countries have had very little access to vaccines, let alone boosters. Accordingly, our first consideration needs to be identifying populations at the highest risk from COVID-19 who might not be protected by the standard vaccinations—immune suppressed patients and possibly the elderly in the next wave.

They generally review available evidence and decide. We have shared our data with the FDA and other regulatory authorities. The best type of evidence is usually considered a randomized controlled trial.