и возможность заразиться зависит от наличия антител.

Как тогда объяснить тот факт, что уже после первой прививки по данным Pfizer риск заразиться снижался на 91,7% на фоне малого количества или полного отсутствия нейтрализующих антител?

The benefit of BNT162b2 immunization started ~11 days post-dose 1, with 91.7% VE from 11days post-dose 1 until dose 2. The study cannot provide information on persistence of protection after a single dose, as 98.5% of participants received dose 2 as scheduled during the blinded study period. As recently reported, although non-neutralizing viral antigen-binding antibody levels rise between the first and second BNT162b2 dose, serum neutralizing titers are low or undetectable during this interval. Early protection against COVID-19 without robust serum neutralization indicates that neutralizing titers alone do not appear to explain early BNT162b2- mediated protection from COVID-19. Other immune mechanisms (e.g., innate immune responses, CD4+ or CD8+ T-cell responses, B-cell memory responses, antibody-dependent cytotoxicity) may contribute to protection.