CBS News reports on a study in Pediatrics that has found that parental refusal to vaccinate children may be directly linked to a pertussis outbreak. Pertussis, or whooping cough, is a contagious respiratory infection that is usually spread through coughing or sneezing. The study looked at data of children who were uneligable to get the pertussis vaccine, either because of allergies or other medical conditions or religious or personal beliefs, and “matched this exception list to the number of pertussis cases in the 2010 California pertussis outbreak. Researchers found that patients in the exemption group were about 2.5 times more likely to develop whooping cough. Pediatricians and other health care officials are urging parents to get their children vaccinated.