Sputnik Astra Zeneca combo

[goji]

Extrapolation does not always work. A half size first dose of the Astra Zeneca vaccine achieves better results than a full first dose (in both cases, followed by a second dose).

[Moses]

Extrapolation does not always work. A half size first dose of the Astra Zeneca vaccine achieves better results than a full first dose (in both cases, followed by a second dose).

It is not about extrapolation, it is about immunity what person already has at time of vaccination.

Simplest example Sputnik or Oxford. Both are vector type on base of adeno-viruses. If person at time of vaccination already has immunity to adeno-virus-A then vaccine with vector adeno-virus-A will not develop immunity against COVID from this injection and here will come second injection which is based on adeno-virus-B. There is possibility what about 8-10% of population already has immunity to adeno-A and adeno-B, and at that case another vaccine based on adeno-C and adeno-D will help, because population who has immunity to all 4 viruses is significantly lower than population with immunity to only 2 of them. That why combination of 2 vector vaccines will work better than solo vaccine.

Half dose of Oxford at fist shot was better than full dose because immunity which body got from first shot was too much strong against vector in second shot, and that immunity (from first shot) kills vector from the second shot before it had chance to develop immunity against COVID.