Opposition to vaccination on political and religious grounds has been swaying parents across the country to refuse immunizations for their children. Recently this has resulted in two of the largest measles outbreaks in New York’s history, impacting haredi Orthodox Jewish neighborhoods. The opposition to vaccines is not confined to the Jewish community, but represents part of an ill-informed nationwide movement opposed to vaccines.As of last week there were 24 confirmed cases of measles in the Brooklyn neighborhoods of Williamsburg and Borough Park, and an additional 75 people in Rockland County had contracted measles as well. Additional cases are under investigation, and the number is expected to rise.Childhood vaccines preserve health, prevent disease and save lives. Proper vaccination is an essential public health strategy and parents must be made aware of the scientific research on this critical issue.Members of our faculty reported in the New England Journal of Medicine on the ability of the childhood viral disease mumps to spread rapidly among children in the close quarters of yeshiva study halls. Similarly, measles seems to thrive in these conditions……Measles may cause pregnant woman to give birth prematurely or to have a low-birth-weight baby. Subacute sclerosing panencephalitis (SSPE) is a rare fatal disease that results from a measles virus infection acquired earlier in life. SSPE generally develops seven to 10 years after a person has measles, even though the person seems to have fully recovered. The risk of developing SSPE may be higher for children who get measles before they are 2 years old.Several Jewish legal authorities have weighed in on requiring children to have vaccines or allowing religious exemptions for school children to avoid vaccination. Recently, in response to the outbreak of measles in the United States and Israel, many have called for universal vaccination. However, there still appears to be some resistance to requiring universal vaccination. One Jewish legal opinion written three years ago justified refusing vaccines on the grounds that the risks of contracting measles were low. These medical “claims” were erroneous then and are erroneous now.