In the words of the courts and Google Translate: The child's right to health is more than the rights of parents to the (wrong) choice.
Croatia's vaccine mandate has been to the great benefit of the country's public health:
No occurrences of diphtheria, whooping cough (pertussis), measles, parotitis and poliomyelitis often called polio or infantile paralysis have been registered in recent years, while tetanus rates have been reduced by 97%, tuberculosis by 93% and hepatitis B, with mandatory vaccination against this disease introduced in 1999, by 65%.
No measles? You're beating America. But anti-vaccination movements are on the rise everywhere that science-averse reactionaries possess a modicum of paranoia and spare time: 28 children in Croatia weren't vaccinated in 2012, then 143 in 2013, and this court decision is the result of a petition signed by 10,000 people who think that "the vaccination of healthy children poses a threat to their health." Superstition, besting science since the beginning of time.