What proportion of children are required to be immunized before starting school?

The understanding that the proportion of children required to be immunized before starting school varies by state reflects the decentralized approach to vaccination requirements in the United States. Each state has its own laws and guidelines regarding immunizations, which typically include a series of vaccinations for diseases such as measles, mumps, rubella, polio, and varicella.

These requirements are set to ensure high vaccination coverage to promote herd immunity, protecting not just vaccinated children but also those who cannot be vaccinated for medical reasons. While there are common vaccinations that are often required, the specific vaccines and their timing can differ from one state to another, leading to the conclusion that there is no universal standard applicable to all children uniformly.

Thus, the correct answer recognizes the variability among states, acknowledging that most states do have some form of vaccination requirement, which supports public health initiatives while adapting to local policies and public health needs.