These curves describe precisely the clinical outcomes seen over the past several months.
July - mild breakthroughs
August - some more serious breakthroughs
September - hospitalizations ticking up
October - ICU/ventilator use rising
November - deaths beginning
So, the experiment of two doses of an mRNA vaccine 21 or 28 days apart, or one dose of J&J, as an adequate or completed primary series is over. It never should have been described as such.
The 15X-50X rise in antibodies after a third dose suggests, but does not prove, that a third dose will complete an adequate primary series. Lots of vaccines need three doses distributed over 6-12 months to induce long-lasting immunity.
When I advise unvaccinated adults who want vaccination now, I suggest 0, 2 and 6 months with an mRNA vaccine, I don’t recommend J&J at present.
Hence the recommendations for a booster at six months.
Which will become a recommendation for a booster every six months in perpetuity.
What boosters would you recommend for someone who has had the J&J vaccine? A J&J booster? One additional mRNA booster? Two?