While the correlation between initial efficacy and duration of protection is consistent across all the vaccines, their individual neutralizing antibody titers varied widely. The Pfizer and Moderna mRNA vaccines performed the strongest, with an initial efficacy of 95 percent that didn’t drop to 50 percent until around day 200. By contrast, the Johnson & Johnson and AstraZeneca adenovirus vaccines, which had an initial efficacy of 67 and 62 percent respectively, reached the 50 percent mark around day 50. At the far end of the spectrum was the Sinopharm vaccine, which had an initial efficacy of 50 percent in the first place and, within the same amount of time, offered next to no protection at all. If this predictive model is indeed an accurate reflection of reality, that means those who receive the Sinopharm vaccine will have the same level of protection immediately after immunization as those who received a Pfizer or Moderna vaccine 200 days prior. The Pfizer and Moderna vaccines also had immunization trajectories similar to those of recovered Covid-19 patients, while the Johnson & Johnson, AstraZeneca, and Sinopharm vaccines fared worse.