It’s an irrational faith in natural foods and yoga as all we need to protect against viral infection. He’s had this faith for a while. In 2005:

Bill Maher has again discussed his anti-vaccination views, this time on Larry King. Among other claims, Maher says that polio was wiped out due to better sanitation, and that getting the flu shot increases your chances of developing Alzheimer’s. Orac has more detail on the claims and the dubious source of the “Alzheimer’s/flu shot” link. I wonder how Maher would explain the decrease in African measles that’s followed an increase in measles vaccination there?

via Bill Maher and his anti-vaccination claims. Again. – Aetiology

It continues today:

I had a Spanish teacher in high school whose leg was ravaged by polio and a friends father who was missing a leg from the knee down due to his bout with polio as a child. No one my age had polio, we all had vaccines, I would venture to guess not all of us ate healthy food.

Could vaccines be improved? Possibly and they probably will be. The NIH and the CDC are working to do that every day. Are they centers of huge profit for these companies? No. Revenue? Yes. Profit? No. Pharmaceutical companies are steadily abandoning vaccine production. They make more money selling over the counter and prescription drugs.

The basic schedule of vaccines our country recommends for the constituencies of babies, toddlers and pregnant mothers do not provide pharmaceutical companies with high profit margins. Vaccines are one of the most important advancements in public health science. Its a shame that two comedians have become two prominent and largely unchallenged voices in popular media regarding vaccines. Jenny McCarthy enabled by Oprah attributes autism to vaccinations and Maher whose disbelief in the science that brought us vaccinations is not compatible with his belief in evolution.

If you think its harmless, or it would just affect the kids who don’t get vaccines, you have only to examine how a few anti-vaccine parents can threaten children with compromised immune systems or even perfectly healthy human beings.