Table 1 Variables tested in the regressions models that were tested for an association with wild and VDPV outbreaks

 Under-immunised

Smoothed % of children under 5 yo with >2 OPV doses

AFP

Both

Y

Y

 Zero-dose

Smoothed % children under 5 yo with 0 OPV doses

AFP

Both

Y

Y

 Routine immunisation

% under 1 yo that received 3+ doses of the DTP vaccine

WHO/Unicef

Both

Y

Y

 Stool surveillance

% AFP cases under 15 yo with adequate^a stool samples processed

AFP

Discrete

Y

Y

 npAFP rate

Number of non-polio AFP cases per 100,000 population under 15 yo

AFP

Discrete

Y

Y

 Wild-type outbreaks

Number of wild-type outbreaks reported in last 4 years

WHO

Both

Y

Not tested

 Wild-type multi-case outbreaks

Number of wild-type outbreaks with >1 case reported in last 4 years

WHO

Both

Y

Not tested

 cVDPV outbreaks

Number of VDPV outbreaks reported in last 4 years

Not tested

Y

 cVDPVs multi-case outbreaks

Number of VDPV outbreaks with >1 case reported in last 4 years

Not tested

Y

 Proximity

Wild-type outbreak present in a bordering country in last 6 months

Cluster description

Discrete

Y

Not tested

 Proximity scaled

The number of poliomyelitis cases in bordering countries in previous six months

Cluster description

Continuous

Y

Not tested

 Migrants

Number of migrants multiplied by incidence within country in previous 6 months

www.migrationdrc.org

Both

Y

Not tested

 Refugees

Number of refugees multiplied by incidence within country in previous 6 months

UNHCR

Both

Y

Not tested

 Displaced

% total population registered as refugees and internally displaced persons

UNHCR

Discrete

Y

Y

 Other events (Ebola)

Adverse humanitarian events that have occurred in the previous 4 years

Expert opinion

Discrete

Y

Y