Sputnik is two vectors: Ad26 and Ad5. That looks like the reason why they kept having a high efficacy (today's press release from Gamaleya says 92%). Dosing is

Sputnik is two vectors: Ad26 and Ad5. That looks like the reason why they kept having a high efficacy (today's press release from Gamaleya says 92%). Dosing is done in Phase 1 trials, which also included antibody level testing. This has been already taken into account in the current trials.