Non-medical vaccine exemptions appear to have contributed to a 2010 pertussis, often called whooping cough, outbreak in California, a study published Sept. 30 in the journal Pediatrics reports. The study compared geographic clusters of individuals that refused the pertussis vaccine to pertussis cases reported to the California Department of Public Health.
Study authors note an increase in pertussis cases over the past decade had been attributed to decreased effectiveness of the vaccine, which has been available since the 1940s. Other factors, such as the cyclical nature of the disease, were also blamed for the outbreak.
The study “Nonmedical Vaccine Exemptions and Pertussis in California, 2010” sought to determine if vaccination refusal was also a contributing factor to the outbreak of more than 9,000 reported cases. In California, families may apply for a Personal Belief Exemption from vaccination mandates.
The study found that areas with high rates of nonmedical vaccine exemptions had higher rates of pertussis cases leading study authors to conclude that voluntary refusal of the vaccine had contributed to the disease outbreak in 2010. Higher levels of nonmedical vaccine exemptions and whooping cough cases were found in areas of the state with higher socio-economic characteristics such as lower population density, higher median income and higher education levels.
Prior to the development of a pertussis vaccine, whooping cough was the leading cause of death among children in the United States. The 2010 outbreak in California resulted in 10 deaths. The pertussis vaccine is combined with vaccines for diphtheria and tetanus in the DTaP vaccination. Children receive a series of 5 doses beginning at 2 months of age. The final dose is usually administered before the child begins kindergarten.
Pertussis usually starts with cold-like symptoms — runny nose, low-grade fever, mild cough and, in infants, pauses in breathing (apnea). This stage can continue for two weeks before advancing to the next stage when the patient begins to suffer fits of rapid coughs followed by a “whoop” sound, vomiting and exhaustion.
The disease is especially dangerous for infants younger than 1 year of age. According to the Centers for Disease Control (CDC), 50 percent of infants contracting pertussis require hospitalization. Of those hospitalized, 23 percent get pneumonia, nearly 2 percent have convolutions, 67 percent suffer slowed or stopped breathing, and nearly 2 percent die.
The most common complications suffered by teens and adults with whooping cough are weight loss, loss of bladder control, broken ribs from excessive coughing and passing out.
Pertussis is generally treated with antibiotics. It is important to begin treatment early as antibiotics are ineffective after three weeks of illness. Over-the-counter cough medicines will not help, and cough and cold medicine manufacturers do not recommend their products for children younger than 4 years of age.