Pneumococcal vaccine decreases by 100% IPD caused by vaccine serotypes

IDSA 49th Annual Meeting

BOSTON — Early data on the use of the 13-valent pneumococcal conjugate vaccine in Alaskan children indicate a sharp decline in invasive pneumococcal disease just 12 months after the introduction of the vaccine in that state, according to a poster presented here.

After 1 year of widespread use of the 13-valent pneumococcal conjugate vaccine (PCV13, Prevnar-13, Pfizer), invasive pneumococcal disease caused by the vaccine serotypes decreased 100% in non-Alaska Native children younger than 5 years and 71% in Alaska native children, according to data presented by Michael Bruce, MD, MPH, from the CDC’s Arctic Investigations Program, Anchorage, Alaska, during the IDSA 49th Annual Meeting.

“We’ve seen essentially a disappearance of the 13-valent types among non-native Alaska children. The rates went from about 20 to zero. In Alaska Native children, we have also seen rates go from about 84 per 100,000 in Alaskan Native children younger than 5 to rates of 24 per 100,000 in the post-vaccine period,” he told Infectious Diseases in Children. “This is a significant decline.”

A decrease was also reported in strains not included in the 13-valent pneumococcal conjugate vaccine (PCV13, Prevnar-13, Pfizer) among Alaska Native children, similar to patterns seen after introduction of 7-valent pneumococcal conjugate vaccine (PCV7, Prevnar, Pfizer).

Rates of IPD declined after statewide introduction of the PCV7 in 2001, but non-PCV7 serotypes began increasing after 2002. The researchers reported that serotypes included in the 13-valent pneumococcal conjugate vaccine comprised 48% of invasive pneumococcal disease before introduction of the 13-valent vaccine in 2010. A herd effect among older patients has not yet been observed, according to Bruce, and the potential development of herd immunity or replacement disease will be evaluated through continued surveillance.

“To me, the important message is that we are seeing effects of this vaccine in the children younger than 5 even at one year,” he said. “We hope this lasts and that we don’t see replacement with the other non-vaccine serotypes.”

Bruce said that additional data he analyzed through September 2011 indicates that the trends are holding true, “so we are still seeing a statistically significant decline in disease rates of the 13-valent types.”

Using the Alaska-wide laboratory based surveillance, the researchers isolated pneumococci from sterile sites and serotyped them using standard methods. Vaccine coverage was evaluated from electronic medical records at Alaska Native medical facilities and the National Immunization Survey. The investigators defined a pre-vaccine time period as April 2006 through March 2009 and a post-vaccine time period as April 2010 through March 2011. The period between April 2009 and March 2010 was excluded because PCV13 was introduced pre-licensure in one high-risk region in 2009.

Previous studies have shown that Alaska-Native children have some of the highest reported rates of invasive pneumococcal disease in the world. — by Cassandra A. Richards

Disclosures: Dr. Bruce reports no relevant financial disclosures.

For more information:

Bruce M. #656. Presented at: IDSA 49th Annual Meeting. Oct. 20-13, 2011. Boston.

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