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I am a 68 yr old American living in Mexico. Traveled to CA 4/2021 (pre-Delta) for J&J vaccine. Received a booster shot on 9/21, approx 5 months after 1st shot. Yesterday, preliminary findings say optimum J&J booster recommended 2 months after original. So, my question is: how protected would you say I am? I have also seen the published info released yesterday re: 'mix 'n match' detailing J&J recipients boosting w/Moderna or Pfizer...thoughts? Thank you kindly in advance.
Two doses of J&J vaccine separated by 2 months was formally studied in a large phase 3 efficacy study, called Ensemble 2. The study results were announced September 21, 2021 and there was 94% efficacy against moderate-severe Covid infection. There is also data that shows when you have two doses of J&J vaccine separated by 6 month, there can be a significant booster effect with the second dose--antibodies boosted to 12-fold higher.
The announcement of data from the NIH mix and match study consisted of very small sample sizes but are encouraging in that it suggests that a J&J single dose vaccination followed by another J&J or any of the mRNA vaccines results in very significant boosted antibody responses. These data should be interpreted with some caution as the antibody levels may not correlate completely with actual protection. Nonetheless, these data are encouraging.
My answer is that you’ve done your best to be protected through vaccination. But we all have to continue to layer on the additional measures to reduce risk of infection and transmission to others. This means we should continue to observe physical distancing and masking.
