Table 1.

Vaccine efficacy (VE) parameters quantified for each of the vaccines evaluated within a selected study using data from vaccinated and unvaccinated control groups within a study. These parameters were quantified from data extracted from selected transmission and challenge experiments

Parameter	Estimation	Description
VE to stop transmission in vaccinated infected birds (VE T )	Based on the value of $\mathrm{R}$ that was directly retrieved from the studies. For a vaccine to be effective to stop transmission ${\mathrm{R}}_{\mathrm{vac}}<1$	$\mathrm{R}$ is the reproduction number estimated in both the vaccinated ${\mathrm{R}}_{\mathrm{vac}}$ and unvaccinated groups ${\mathrm{R}}_{\mathrm{unv}}$. This parameter was obtained only from studies performing transmission experiments. For the study to be valid for data extraction ${\mathrm{R}}_{\mathrm{unv}}$ had to be > 1
VE to reduce susceptibility to infection in vaccinated birds (VE s )	${\mathrm{VE}}_{\mathrm{s}}=1-{\mathrm{S}}_{\mathrm{vac}}/{\mathrm{S}}_{\mathrm{unv}}$	$\mathrm{S}$ is the proportion of infected animals following direct inoculation of the virus estimated for the vaccinated ${\mathrm{S}}_{\mathrm{vac}}$ and unvaccinated ${\mathrm{S}}_{\mathrm{unv}}$ groups
VE to reduce mortality in vaccinated infected birds (VE m )	${\mathrm{VE}}_{\mathrm{m}}=1-{\mathrm{M}}_{\mathrm{vac}}/{\mathrm{M}}_{\mathrm{unv}}$	$\mathrm{M}$ is the proportion of birds dying following infection estimated for the vaccinated ${\mathrm{M}}_{\mathrm{vac}}$ and unvaccinated ${\mathrm{M}}_{\mathrm{unv}}$ groups
VE to reduce virus shedding in vaccinated infected birds (VE sh )	${\mathrm{VE}}_{\mathrm{Sh}}=1-{\mathrm{L}}_{\mathrm{vac}}/{\mathrm{L}}_{\mathrm{unv}}$	$\mathrm{L}$ is the level of virus shed (log10 transformed) in the vaccinated ${\mathrm{L}}_{\mathrm{vac}}$ and unvaccinated ${\mathrm{L}}_{\mathrm{unv}}$ groups
VE to reduce susceptibility and shedding in vaccinated infected birds (VE s,sh )	${\mathrm{VE}}_{\mathrm{s},\mathrm{sh}}={\mathrm{VE}}_{\mathrm{s}}+{\mathrm{VE}}_{\mathrm{sh}}-\left({\mathrm{VE}}_{\mathrm{s}}*{\mathrm{VE}}_{\mathrm{sh}}\right)$	According to the above‐described VEs and VEsh