In the April 24 Kyodo article, "Some municipalities set to deny services to illegal foreign residents: poll," I was appalled to read that "33 [municipalities] said they will not vaccinate illegal foreigners against tuberculosis and other diseases" (when the revised basic resident registration law takes effect).

Don't they know what vaccination programs are for? Vaccination protects the population as well as the individual. Public health research indicates that the "herd immunity threshold" — the proportion who need to be vaccinated to stop the chain of disease transmission — is around 80 to 95 percent of the population. Herd immunity is our only protection for infants too young to be vaccinated and for those with weakened immune systems.

If the 33 municipalities do not see sense — if nativism trumps public health — I would advise mothers to keep their kids away from illegal aliens until they've had their jabs.

The opinions expressed in this letter to the editor are the writer's own and do not necessarily reflect the policies of The Japan Times.

peter mcarthur