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Added serotypes in PHiD-CV led to further reductions in IPD incidence
51st ICAAC
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CHICAGO — The pneumococcal Haemophilus influenzae protein D conjugate vaccine enhanced reductions in invasive pneumococcal disease incidence first seen after introduction of the 7-valent vaccine in Quebec City, Canada, according to findings reported here at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy.
Ngoc-Hang Khuc, of Greenwich Statistics in Paris, told Infectious Diseases in Children that changes have been seen in invasive pneumococcal disease (IPD) incidence as a result of introduction of the 7-valent pneumococcal conjugate vaccine (PCV7; Prevnar, Wyeth) and the pneumococcal Haemophilus influenzae protein D conjugate vaccine (Synflorix, GlaxoSmithKline ).
Quebec was the first jurisdiction in the world to recommend a 2+1 PCV schedule. The program was implemented in December 2004 with a catch-up for children aged younger than 5 years, according to the researchers. "The incidence of IPD changed quickly after implementation of the program," Khuc said. "The decrease was more than 63%, and a good portion of this was in children younger than 5."
Incidence of IPD in children aged younger than 5 years was 72/100,000 in 2001, decreased to 21/100,000 in 2006 and then increased to 30/100,000 in 2009, according to the results.
Vaccine-type IPD decreased in frequency by 99% between 2000 and 2009, but non-vaccine types — particularly serotype 19A — became more prevalent before the pneumococcal Haemophilus influenzae protein D conjugate vaccine was introduced. Among individuals aged 5 years and older, the decrease in frequency of vaccine-type IPD was about 75%. However, the emergence of other serotypes once again tempered the benefit.
The researchers analyzed cases of IPD reported to public health authorities between 2000 and 2010. Eligible isolates had been submitted to the provincial reference laboratories during that period.
“A 2+1 dose program with high uptake seems to be as effective as a 3+1 program for children,” the researchers concluded.
"What is of particular interest with these data is that the further decrease in the 6 to 11 months of age cohort does not seem to be only linked to the added serotypes in the PHiD-CV vaccines, indicating the importance to analyze the overall effect of these newer vaccines, rather than extrapolate the effect based on the serotype content only," Bernard Hoet, MD, FFPM, Director Global Medical Affairs for Synflorix in the department of Global Vaccine Development, GlaxoSmithKline Vaccines, told Infectious Diseases in Children.
Hoet also noted that a previous version of this article reported incorrectly that the vaccine used was the 13-valent pneumococcal conjugate vaccine, and not the pneumococcal Haemophilus influenzae protein D conjugate vaccine. — by Rob Volansky
Disclosure: Dr. Khuc reported no financial disclosures.
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After widespread immunization of children with pneumococcal conjugate vaccines, there have been reports of changes in rates of invasive disease in various age groups and in various geographic sites abound. In this report from Canada using a conjugate vaccine series consisting of only a two-dose priming schedule with a one-dose booster, the authors demonstrate a reduction in the rate of vaccine serotypes in both the immunized population and in older individuals. However, they also point out that serotype replacement has occurred and that the overall rates of invasive pneumococcal disease are not different now than before widespread conjugate vaccine use in children. In addition, the authors conclude that the two plus one series is as effective as the three plus one series, but do not provide data to support that contention. It is curious why different results are seen for the conjugate pneumococcal vaccine in different populations and with different dose schedules.
Kathryn M. Edwards, MD
Infectious
Diseases in Children Editorial Board member
Disclosure: Dr. Edwards reports no relevant financial disclosures.
For more information:
- DeWals P. #G3-781. Impact Of A 2+1-dose Pneumococcal Conjugate Vaccine Program on the Epidemiology of Invasive Pneumococcal Disease in the Province of Quebec, Canada. Presented at: 51st ICAAC. Sept. 17-20, 2011. Chicago.
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