A serious lung infection called pneumococcal empyema has been on the rise in children since the PCV7 vaccination was introduced in 2000, according to researchers at the University of California, Davis, Children’s Hospital. The study appears in the January issue of Pediatrics.
The PCV7 vaccine prevents the development of pneumococcal disease. According to The New York Times, prior to its introduction, pneumococcal disease caused more than 700 cases of meningitis in children, 13,000 blood infections, about 5 million ear infections and 200 deaths in the U.S. each year. Use of the PCV7 vaccine has been credited with reducing the number of children hospitalized for pneumonia because of pneumococcus by 50 percent and bacterial pneumonias have decreased overall.
Unfortunately according to the study detailed in Pediatrics, there has been a 70 percent increase in the rate of a pneumonia complication called empyema. Empyema is a accumulation of dense pus between the outer surface of the lung and the chest wall. The infection interferes with breathing, and surgery is often needed, the Times said.
For their study, the UC Davis researchers analyzed data from the national Kids’ Inpatient Database for the years 1997, 2000, 2003 and 2006. From 1997 to 2006, the empyema-associated hospitalization rate for children aged 18 and younger increased 70 percent, from 2.2 per 100,000 to 3.7 per 100,000. The rate of complicated pneumonia — which includes empyema — increased 45 percent between 1997 and 2006, when the rate was 5.5 per 100,000.
The mean age of children hospitalized with empyema decreased from slightly more than seven in 1997 to just above six in 2006. Among children younger than 5, the rate of empyema increased 100 percent, from 3.8 per 100,000 in 1997 to 7.6 per 100,000 in 2006.
The researches surmised that the increase in empyema cases occurs because the PCV7 vaccine does not affect the types of microorganisms causing empyemas. Because the vaccine is so effective at reducing pneumococcal bacteria that cause most pneumonia and other types of invasive pneumococcal disease, levels of those remaining microorganisms may increase because they don’t have to compete against the other pneumococcal bacteria anymore.