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Any updates on whether recent vaccine for other diseases offers protection against COVID?

Note: No Q&A tomorrow. Happy Labor Day!

Question: Yesterday’s post on Vitamin D reminded me of another (relatively simple) approach that’s hypothesized to offer protection against infection — recent vaccine for other diseases. I think you’ve written about this in previous posts. Any updates?

Answer: Yes! We’ve discussed the hypothesis that other vaccinations — like MMR, BCG, and polio — could prove protective against COVID-19 infection (see Q&A of 6/24 #Polio and Q&A of 4/27 #TB). Now there’s a bit more research out on BCG, and here’s the scoop:

  • Last week, Cell published “ACTIVATE: RCT of BCG Vaccination against Infection in the Elderly.” The study, though not focused on COVID-19, found promising results that very much relate to COVID-19. Specifically, analyzing data from their prospective, randomized control trial that included individuals ages 65+, authors found that recent BCG vaccination increased time to first infection (11 weeks among placebo vs. 16 weeks among BCG intervention), decreased the incidence of new infection (42% among placebo vs. 25% among intervention), was especially protective against viral respiratory tract infections (79% reduction in risk among BCG intervention compared with placebo), with no difference in the frequency of adverse events (i.e. it’s safe among the elderly!).
  • Two weeks ago, Clinical Infectious Diseases published, “BCG vaccination in infancy does not protect against COVID-19. Evidence from a natural experiment in Sweden.” Using birth cohort data from just before and just after BCG vaccination at infancy was introduced in Sweden (i.e. around 1975), the authors tested whether BCG vaccination at birth proved protective against COVID-19 infection, hospitalization, or death in middle age. Alas, they found no such protective effect. These findings diminish the hypothesis put forward by some scientists that cross-country differences in COVID-19 incidence and severity can be attributed to BCG vaccination policy. This study cannot, however, tell us anything about the immunity benefit of recent BCG vaccination on COVID-19 incidence and outcomes.