Had a read through of the paper and am a bit confused about the data on transmission.
Both low dose/standard dose (LDSD) and standard dose/standard dose (SDSD) reduced incidence of symptomatic covid, but there was no impact on asymptomatic disease in the SDSD cohort. Which I would take to mean that combo doesn't stop you getting infected but stops you developing symptoms.
But how does this then relate to this part of the paper, which is used to determine impact on transmission?
"If there was no impact of a vaccine on asymptomatic infection, it would be expected that an efficacious vaccine would simply convert
severe cases to mild cases and mild cases to asymptomatic, with overall PCR positivity unchanged. A measure of overall PCR positivity is appropriate to assess whether there is a reduction in the burden of infection. Analyses presented here show that a single standard dose of the vaccine reduced PCR positivity by 67%, and that, after the second dose, the SD/SD schedule reduced PCR positivity by 49.5% overall. These data indicate that ChAdOx1 nCoV-19, used in the authorised schedules, may have a substantial impact on transmission by reducing the number of infected individuals in the population."
I'm clearly misunderstanding something - can anyone shed any light?