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PCV13 reduced colonization with PCV6+ in Alaskan children, adults
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Since the 13-valent pneumococcal conjugate vaccine replaced the 7-valent pneumococcal conjugate vaccine, colonization with the six additional serotypes significantly declined among both rural and urban children younger than 5 years and among adults older than 18 years in Alaska, researchers from the Arctic Investigations Program at the CDC reported.
“By 2009, the six additional serotypes included in the PCV13 accounted for 55% of all invasive pneumococcal disease cases in Alaska,” the researchers wrote in the Journal of Infectious Diseases. “The proportion of Alaskan children age-appropriately vaccinated was high and comparable with children in the general US population. Vaccinating children with PCV13 resulted in decreased colonization by vaccine serotypes directly among children and indirectly among unvaccinated adults during 2011-2012.”
Children in Alaska began receiving PCV13 (Prevnar 13, Pfizer) vaccination in April 2010. From 2008 to 2012, the researchers collected 18,207 nasopharyngeal swabs, of which 16,098 were collected from rural sites. The remainder was collected from two urban pediatrics clinics. The swabs were analyzed to identify and serotype Streptococcus pneumoniae isolates.
Among children younger than 5 years, vaccine coverage ranged from 81% to 89% in rural children and from 89% to 92% in urban children. The proportion of participants who were colonized was stable throughout the study period, with an average prevalence of 66% for rural children, 35% for urban children and 14% for adults older than 18 years.
The researchers identified 36 different pneumococcal serotypes. The prevalence of PCV13 serotypes declined significantly in all age groups. Colonization with the six additional (PCV6+) serotypes declined from 25% to 5% among rural children younger than 5 years, from 22% to 9% among urban children younger than 5 years and among adults older than 18 years.
“Additional years of data should be collected to understand the full efficacy of the vaccine and to determine whether the reduced prevalence of PCV6+ serotypes will be sustained,” the researchers wrote. “The increase in colonization by non-vaccine serotypes is of concern because this might result in increased rates of invasive pneumococcal disease. Therefore, ongoing invasive pneumococcal disease surveillance is necessary in order to monitor the impact of emerging serotypes.”
Disclosure: Two researchers conducted PCV13 research sponsored by Pfizer.
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