To health experts' dismay, many parents who decide against vaccinating their children are not only from poor or marginalised communities but from well-off families too.
Measles, a potentially deadly disease that was once eliminated in the US, has made a comeback in recent years.
It has reached college-going students whose families in affluent areas are skipping vaccinations.
"It's that hybrid-car community that says, 'We're not going to put chemicals in our children,'" Nina Shapiro of University of California was quoted as saying.
Measles cases are on the rise throughout California. The Los Angeles County Department of Public Health has issued a reminder to doctors that they must report all measles cases as soon as possible.
"Parents have varied reasons for choosing not to immunise their children. Some are concerned that vaccinations raise the risk of autism although study after study has debunked this myth," Shapiro was quoted as saying in a Los Angeles Times report.
These diseases do exist and we are already seeing some of them make a comeback in well-to-do families, she added.
Even in places where vaccinations are required, exemptions are easily obtained for religious or other reasons.
Some people, it seems, have forgotten how devastating many communicable diseases are, she emphasised.
Some private schools have vaccination rates as low as 20 percent.
"Parents are willingly paying up to $25,000 a year to schools at which fewer than one in five kindergartners has been immunised against diseases like measles, polio, meningitis and pertussis," Shapiro explained.
Measles is a highly contagious respiratory disease caused by a virus; symptoms include rash, fever, runny nose and cough.
