Could be, but that's well outside my range for safe, ignorant, speculation. Experts (people who actually work with that stuff) figured out that schedule, who am I, to question it? Such questioning, particularly during this time of lying propaganda to get folks to not vaccinate undermines the efforts to save lives.Tangent:
With several tens of millions of COVID-vaccinated people to survey, a straightforward question could be asked: When did you get your shots, and how far apart were they? Please get an effectiveness test and report those results.
Most childhood vaccines that require two-plus shots are given 3 or 6 or 12 months apart, and they 'stick' for the long term. The current difficulty might be rooted in the two-to-six week schedule between shots being used.