About 2 p.m. on April 30, Donald Herbert announced that he wanted to speak to his wife.

Nothing unusual about that. Except Herbert had been silent since 1995. The former firefighter suffered brain damage when a roof collapsed on him, and doctors thought he?d never speak again. But there he was, asking for his wife.

It?s amazing how much we don?t know about the human body.

?We need to study hundreds if not thousand of patients like this so we can make generalizations,? Dr. Joseph Fins of Cornell University told CNN. ?Right now we can?t predict which patient will have this kind rebooting and who will remain in permanent unconsciousness.?

Further brain study is important. But we?d all benefit if doctors showed the same curiosity about whether our childhood vaccination policy needs improvement. Sadly, doctors seem less interested in that.

?I disagree with your article on vaccinations,? a pediatrician from Boulder, Colo. e-mailed after my column recommending we delay -- not cancel -- some childhood vaccinations. He extolled the virtues of one in particular. ?Chickenpox killed 150 children a year -- previously healthy children -- and they died horrible deaths,? he wrote. ?Recent data in the New England journal showed a reduction in deaths of children 1-4 years of age of 92 percent with the chickenpox vaccine.?

Saving 150 lives sounds impressive, but if we want to save the most children possible, we should forget about vaccinations and instead ban automobiles. The National Highway Traffic Safety Administration says an estimated 41,800 people died in crashes in 2000. That includes 2,835 children younger than 15. All of those deaths could be prevented if we gave up our cars.

But we?re willing to accept those deaths, because we think that getting to our jobs, the grocery store, soccer practice and so forth is worth the risk. In other words, we?ve compared the risks of cars with the rewards.

However, we haven?t really calculated the long-term risks that may be associated with vaccinations. Consider: The number of vaccines the Centers for Disease Control recommends before a child turns two has almost tripled since 1988 (chickenpox is one of those new vaccines). Meanwhile, a report by the state Department of Development Services showed the number of autism cases in California increased more than six times between 1987 and 2002.

Coincidence? The Boulder pediatrician thinks so. ?The incidence of autism parallels the increase of funding by the federal government for that diagnosis in school children,? he wrote. ?As one expert, James Cherry, MD of Stanford says, ?If you go outside in the rain and there are frogs on the ground, you cannot conclude it rained frogs.?? Continued...