ACIP assesses pneumococcal vaccine, HPV, and more

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Immunization Update

Addressing areas of concern in the vaccine world was the focus of the June 25–26 meeting of CDC’s Advisory Committee on Immunization Practice (ACIP). As APhA’s representative to ACIP, I prepared this highlights summary for Pharmacy Today. More in-depth notes from the pharmacist’s perspective are online in the Immunization Center on pharmacist.com, and complete minutes of the meeting will be published on CDC’s website. In addition, three topics presented at June’s meeting on influenza vaccines, meningococcal vaccine, and vaccinations in immunocompromised patients are covered as separate articles in this issue’s Special Immunization Section on pages 42–46.

Pneumococcal conjugate vaccine

As mentioned at the February ACIP meeting, a three-dose, 13-valent pneumococcal conjugate vaccine (Prevnar 13 [PCV13]—Pfizer) schedule is used in many other countries, whereas the United States currently has a four-dose schedule. The ACIP working group was tasked with re-evaluating the current U.S. schedule.

CDC has been monitoring invasive pneumococcal disease and evaluating serotypes that have caused disease. The serotypes in the 7-valent pneumococcal conjugate vaccine (Prevnar 7 [PCV7]—Wyeth) have virtually disappeared, and the serotypes in PCV13 vaccine are rapidly disappearing. A Grading of Recommendations Assessment, Development, and Evaluation (GRADE) analysis for reducing the number of doses of PCV13 in the pediatric schedule demonstrated limited evidence for three versus four doses. The working group noted that it was still not ready to make a recommendation for change but will continue its evaluation.

The Community-Acquired Pneumonia Immunization Trial in Adults (CAPiTA) results were also presented. Although FDA licensed PCV13 for adults older than 50 years, ACIP has not recommended this use. CAPiTA was a randomized, controlled trial of PCV13 compared with placebo in 84,496 patients older than 65 years. The primary study tested the efficacy of PCV13 in preventing vaccine-serotype pneumococcal community-acquired pneumonia (CAP). The trial reported a 46% reduction in CAP, with 49 cases in the vaccine group compared with 90 cases in the placebo group.

The ACIP working group was tasked with considering if PCV13 should be administered routinely to all adults aged 65 years or older. Members estimated that the number needed to treat to prevent a single case of PCV13-type invasive pneumococcal disease was 20,400; 1,620 for inpatient CAP; and 1,110 for outpatient CAP. The GRADE analysis supported the use of PCV13 in adults; however, herd immunity may limit the need for PCV13 in the future.

Thus, ACIP concluded that a short-term recommendation may be warranted. Since a timely decision is needed for the 2014–15 respiratory season, the committee may meet over the summer to discuss the issue further.

Human papillomavirus vaccine

Clinical data on the new 9-valent human papillomavirus (HPV) vaccine by Merck were presented, continuing the presentation introduced at February’s meeting. The 9-valent HPV vaccine has proven to be very effective (97%) in reducting disease caused by the new HPV serotypes and noninferior to the serotypes in the original vaccine. In addition, the safety profile appears to be similar to that of the original vaccine, with local reactions the most common adverse effects.

Based on these studies, the 9-valent HPV vaccine will be licensed for girls and women aged 9 years to 26 years and for boys aged 9 years to 15 years. Studies have been performed evaluating a two-dose schedule, and the ACIP working group is evaluating whether decreasing to two doses from the current three doses should be considered.

Extending the interval between the doses may also be an important issue, and several ongoing trials are evaluating this factor. The ACIP working group plans to evaluate the 9-valent HPV vaccine and compare a two- versus three-dose schedule.

Yellow fever vaccine

While several yellow fever vaccines are used around the world, YF-Vax (Sanofi Pasteur) is approved for use in the United States. The vaccine is recommended for persons aged 9 months or older who are traveling or living in areas at risk. It is given in a single subcutaneous dose at intervals of 10 years. Many contraindications and precautions exist, and careful screening must be performed. Reviews of the literature show that 90% of vaccine recipients have high antibodies at 10 to 20 years. High titers have been detected as long as 60 years postvaccination, and very few vaccine failures have been reported.

In April 2013, the Strategic Advisory Group of Experts for the World Health Organization recommended eliminating the yellow fever vaccine booster. A GRADE analysis was applied by the ACIP working group; however, very few data are available. The working group recommended that booster doses no longer be administered to most travelers or laboratory workers. After discussion by several experts opposed to the recommendation because of limited data, ACIP postponed a vote until it reconvenes October 29–30.

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