Story highlights A lawmaker introduced an amendment to a bill reforming the state's foster care system

The so-called "anti-vaccination amendment" sparked heated debate among Republicans

(CNN) Debate about a bill before the Texas House about improving care for foster children quickly broke down into a heated argument about vaccinations on Wednesday, with one of the state's most conservative lawmakers saying vaccines weren't important for public health.

The anti-vaccination forces ultimately won, voting to bar doctors from vaccinating foster children during initial examinations. When one Republican tried to get an exemption for the human papillomavirus vaccine, tempers flared.

The vote signified a major victory for the growing influence of the tiny but well-funded anti-vaccination crowd in Texas, one political observer said.

"It's analogous to a very tiny tail wagging a very massive dog," said Mark Jones, a political science professor at Rice University. "The anti-vax forces are a tiny group that holds an exceptionally minority position on the effectiveness of the vaccinations but are influencing public policy."

The debate came after Rep. Gene Wu, D-Houston, introduced a bill to reform the state's foster care system. Wu seemed surprised when conservatives questioned him about a provision requiring foster children to get prompt exams from doctors to determine whether they've been abused, neglected or abandoned.