Question: Based on Sunday’s post about lasting immunity, would it make sense to take into account previous COVID infection as we prioritize who gets the vaccine?
Answer: Given what we currently know about lasting immunity and what our vaccine distribution/administration experience has been to date, I do not think that adding another criterion for vaccine prioritization would be helpful. First, immunity post-infection may not be lasting at the individual-level (described further below). Second, vaccine distribution has already been challenging in the US with a great deal more vaccines distributed than administered. As of Monday, 25.5M vaccines were distributed of which 9M vaccines were administered across the country. Adding yet another criterion will further complicate the roll-out.
Not everyone agrees with my assessment (believe it or not)! I just read in the Washington Post this morning that Ireland is contemplating asking those who have been previously infected to wait to get the vaccine. In the context of limited vaccine supplies, this could make sense. But the WaPo article also quotes Boston University epidemiologist, Dr. Eleanor Murray, who states, “Confirming whether or not someone has had covid already adds an unnecessary layer of red tape onto vaccine prioritization. Given that the prioritization is designed to get vaccine first to those people who are most likely to get infected and/or get very sick from infection, it makes sense to reduce the barriers to vaccinating this group as much as possible,”
More on Lasting Immunity: The study from Science I cited on Sunday found huge heterogeneity among participants in terms of their immune memory. That to say– the study indicates that at a population level, immunity seems to be lasting for at least many months, but given differences between individuals, this effect may not hold at the individual-level. To de-prioritize folks who have previously been infected– especially folks who remain at higher-risk due to their employment, age, or underlying conditions– may unduly put them at risk of reinfection. Note: cases of reinfection remain rare at this point, but they are indeed possible (see Q&A of 11/21) .