As we reported recently, a new study has found that the Tdap booster meant to prevent whooping couch in children — a vaccine that is mandated in many states — isn’t effective after a few years. It also raises what has become a growing questions — should vaccines be mandatory for school children?

The anti-vaccination movement has been growing by leaps and bounds in recent years, arguing that vaccines can result in autism in children and questioning just how effective they are. The scientific community overwhelmingly disagrees with them, but it hasn’t stopped the anti-vaccination movement from gaining new followers even as critics slam them for recklessly allowing the return of long-eradicated diseases. Now, they’re likely to have more ammo with the report that the Tdap booster’s effectiveness in preventing pertussis, or whooping cough, declines to as low as 9 percent of children in the fourth year — a booster that is required in many states.

California last year signed into law a controversial measure that would remove most of the state’s exemptions for vaccinations, removing from parents the right to refuse vaccinations in almost all cases. The move stemmed from a recent measles outbreak at Disneyland.

The law sparked anger among parents who complained that the government was trying to force parents to make decisions they did not feel were in the best interest of their children. However, many praised the laws as a necessary measure in a society where diseases were back on the rise because of a lack of vaccinations, according to a Today.com report.

But there is some concern that the California bill will only inflame anti-vaccination parents and also push some on the fence about the subject squarely onto the anti-vacciation side. Whether that actually happens is the big question in the coming years, as other states examine their own pro-vaccination measures.