Smallpox doesn't kill everyone. It seems only about thirty percent actually die from it. The rest are usually disfigured. Older people and those with weak immune systems are at more risk. That's wild -- as opposed to bioengineered -- smallpox that has the 30% fatality rate. I think something like 50% of those exposed to the Soviet bioengineered variety that was let loose in Kazakhstan around 1970 died.
3 of 7 died. All 3 had not been vaccinated. The problem is that the sample size is too small.