In the United Kingdom, a study showed that
4 years after a single dose of MMR vaccine the seropositivity
rates were 85% for the Urabe strain, compared
with 81% for the Jeryl Lynn strain (69). In
Canada, a study found that 5–6 years after one dose
of MMR vaccine the seropositivity rate was 93%
for the Urabe strain, compared with 85% for the
Jeryl Lynn strain