“Vaccine for All? Math model supports mass smallpox inoculation” failed to mention an important complication for any type of smallpox-inoculation program: The vaccine might not work. A smallpox outbreak could be caused by a viral strain purposely engineered to evade any commercially available vaccine. Also, how likely is it that a new smallpox vaccine would produce the same successful result in me that I got when I was vaccinated as a child? How about side effects from a modern vaccination? I need more information about the science of smallpox inoculation before I’ll willingly submit to a booster-immunization strategy.

Hector Sanchez
Pine Bluff, Ariz.

Your article’s assumption of a close to 30 percent death rate from smallpox infection is unrealistic. For adults it is 10 to 15 percent. Sure, if you want to you can model a worst-case scenario. How about: The terrorists have a genetically engineered version of smallpox that can kill most of those vaccinated with present smallpox vaccines. Vaccines kill one out of a thousand, not the one out of a million as presently assumed, and injure over one out of a hundred. (The one-in-a-million figure is based on old data that applied before the American people suffered so much autoimmune disease as at present.) Would you still conclude that mass vaccination is a good option?

Gary M. Cohen
Milwaukie, Ore.