Thanks to my favorite troublemaker, Hank Campbell, the "who is more anti-vaccine" debate has sprung up again. In 2012, we co-authored a book, Science Left Behind, in which we argued that the anti-vaccine movement began with the political Left, but spread to religious conservatives and libertarians. However, because the most visible public spokespeople for the anti-vaccine movement (e.g., Robert F. Kennedy, Jr., Bill Maher, and Jenny McCarthy) are mostly on the political Left, we continue to believe that the Left should bear most of the blame. However, some writers argue that the anti-vaccine movement is truly a bipartisan phenomenon.

New CDC data helps shed some more light on the issue. The CDC has compiled an updated list which depicts vaccine exemption rates in each U.S. state. (See map.)

As shown above, 11 states have 4% or more of the kindergarten population exempted from vaccines. (Generally speaking, the number of religious/philosophical exemptions dwarfed the number of medical exemptions.) The worst 11 states are listed below, from most exemptions to least, in addition to their Obama-Romney 2012 presidential vote margin (as a quick-and-dirty proxy for how liberal or conservative the state is):

Oregon (7.1%); Obama +12

Idaho (6.4%); Romney +32

Vermont (6.2%); Obama +36

Michigan (5.9%); Obama +9

Maine (5.5%); Obama +15

Alaska (5.3%); Romney +14

Arizona (4.9%); Romney +9

Wisconsin (4.9%); Obama +7

Washington (4.7%); Obama +15

Colorado (4.6%); Obama +5

Utah (4.4%); Romney +48

*Note: Illinois, Minnesota, Missouri and Wyoming did not report 2013-2014 data. However, according to the CDC's 2012-2013 data, Illinois had a vaccine exemption rate of 6.1%. (Its vote margin was Obama +17.) The other states had exemption rates below 4%.

The award for the most anti-vaccine state in the country goes to Oregon. This is not a surprise; the citizens of Portland are also afraid of fluoride. Thus, 4 of the 5 most anti-vaccine states are solid blue. (If Illinois is included, 5 of the 6 most anti-vaccine states are solid blue.) Including Illinois, 8 of the 12 most anti-vaccine states voted for Obama.

Which states are the most pro-vaccine (i.e., the states with exemption rates below 1%)?

Mississippi (<0.1%); Romney +11

West Virginia (0.2%); Romney +26

Virginia (0.6%); Obama +4

Alabama (0.7%); Romney +23

Delaware (0.8%); Obama +19

Louisiana (0.8%); Romney +17

New York (0.8%); Obama +28

Kentucky (0.9%); Romney +22

The two most pro-vaccine states are solid red, and 5 of the 8 most pro-vaccine states overwhelmingly voted for Romney.

There are a few other points worth making. First, the anti-vaccine movement has a strong presence in the West. The Western U.S., particularly states like Alaska, Idaho, and Washington, have a strong libertarian streak. This libertarianism surely plays a significant role in anti-vaccine ideology. Second, as a whole, the conservative and religious Deep South is the most pro-vaccine part of the country.

The bottom line is that the CDC data makes it very difficult to argue that conservatives and liberals share equal blame in the anti-vaccine war. Anti-vaxxers are clearly more associated with the political Left.

Source: Centers for Disease Control and Prevention. "Vaccination Coverage Among Children in Kindergarten — United States, 2013–14 School Year." MMWR 63 (41): 913-920. (Oct. 17, 2014.)

(AP photo)