Immunization Update and ACIP Highlights - February 2012

March 16, 2012
The Advisory Committee on Immunization Practices (ACIP) of the CDC met February 22 and 23 to provide updates on vaccines. Below are the key highlights:


  • Tdap vaccine has been given a full recommendation for all adults, including those age 65 years and older.
  • There has been a mild influenza season so far. ACIP continues to recommend antivirals for treating influenza.  The vaccine subcommittee of the FDA has recommended 2 new vaccine strains for the 2012-13 season.
  • No recommendation at this time for providing PCV13 (Prevnar) to adults
    • ACIP will likely vote on a recommendation for use of PCV13 in the immunocompromised in June
    • ACIP will wait for results of CAPITA study in the Netherlands before voting on use in healthy adults ages 65 years old and older


Tdap Vaccine in Older Adults


The ACIP voted to approve the following expansion of the Tdap recommendation in older adults: “For adults ages 19 years and older who previously have not received a dose of Tdap, a single dose of Tdap should be given.”
Previously, Tdap was given a permissive recommendation in adults age 65 years and older, with a full recommendation for those in close contact with infants.  Now all adults ages 65 years and older are fully recommended to receive a dose of Tdap if they have not previously received a dose.
Immunogenicity and safety data were reviewed for Tdap in older adults.  Data is not available in regards to efficacy of the vaccine and incidence of disease in this age group, which are both assumed to be lower than adolescents and young adults.  Cost-effectiveness modeling was conducted by both the CDC and GSK using data known and assumptions for those factors where data was lacking.  The vaccine was considered to be cost-effective in the population ages 65 years and older.
ACIP recognized that only one brand of Tdap is approved by the FDA for use in populations ages 65 and above. The group does not want to create missed opportunities for vaccination by showing preference for one brand over another and recommends that both brands are valid. ACIP commented that BOOSTRIX has been approved by the FDA for all ages 10 and older, while Adacel did not receive FDA approval for ages 65 years and above because non-inferiority criteria were not met when comparing antibody response to the 4-dose Daptacel series.
Adolescent data was reviewed showing a reduced burden of pertussis in adolescents, but no evidence of “herd immunity.”  The burden of pertussis in children under age 10 years appears to be a “cohort effect” from the shift from whole-cell pertussis (wP) to acellular pertussis (aP) vaccines.

The next efforts concerning Tdap by ACIP include the production of a revised, consolidated single statement, and then review of data for recommendations around revaccination with Tdap.
No new influenza recommendations were made by ACIP.  Early treatment of disease using antivirals was re-emphasized.  All current circulating strains of influenza are susceptible to both Oseltamivir and Zanamivir.
Currently, only California has widespread influenza activity.  Type A (H3) has been the predominant strain in the nation, and A(H1N1) has been predominant in Utah.  Very little type B activity has been seen so far this year.  This year appears to be a milder season than previous years, but it may just be delayed as the peak has not yet occurred.

The new high-dose influenza and intradermal vaccines have continued to be monitored for safety.  No safety concerns have been seen with either product.
VRBPAC met the week after the ACIP meeting and decided on the three strains of influenza virus to be included in the 2012-2013 season vaccine.  The committee voted to retain the A/California/7/2009 (H1N10-like virus (the H1N1 pandemic strain), and have replaced the A/Perth/2009 (H3N2) strain with A/Victoria 361/2011 (H3N2)-like virus.  The influenza B/Brisbane/60/2008-like virus will be replaced by the B/Wisconsin/1/2010-like virus.  Due to changes in 2 strains, the 2-dose algorithm for children may be revised and will be voted on at the June ACIP meeting. 
13-Valent Pneumococcal Conjugate Vaccine (PCV13) 
PCV 13 was recently approved by the FDA for use in adults ages 50 years and above.  The approval was based on immunogenicity studies showing non-inferiority to PPSV23 in the 12 serotypes that are common to both vaccines, and with the caveat that post-licensure study would occur.  The ACIP plans to vote on a recommendation for immunocompromised adults in the June 2012 meeting and plans to delay recommendations for the general adult population age 65 and above until 2013 when the results of the CAPITA trial are expected.  ACIP is using an evidence based approach in evaluating the use of PCV13 in adults.  There is limited efficacy data for PCV13 at this time.  Currently, a study in HIV positive adults in Malawi shows efficacy of PCV7 vs. placebo against pneumococcal bacteremia, but does not have data concerning pneumonia as an endpoint.  The CAPITA trial is looking at efficacy of PCV13 vs. PPSV23 against pneumococcal pneumonia. 
The other confounder is herd immunity protection of adults due to the use of PCV13 in children.  The herd effect of PCV7 was dramatic in adults.  At this time it appears that there may be herd immunity developing for children under age 2 years for the new PCV13 vaccine, but there is not enough data yet for adults.  If there is enough herd immunity provided by the vaccination of children, the use of PCV13 in adults may not be an appropriate public health strategy.
Immunocompromised adults have a 20-fold higher incidence of invasive pneumococcal disease than healthy adults.  If the Malawi data are extrapolated to the United States population, it is estimated that the number needed to vaccinate to prevent one case of invasive disease would be 2,011.  ACIP will consider voting on a recommendation to vaccinate immunocompromised adults of all ages with PCV13 in the June 2012 meeting. 
Future Recommendations 
ACIP continues to review:
• PCV13 vaccination in adults
• Meningococcal vaccination in infants
If you have any questions regarding immunization, feel free to contact Tamara Sheffield, MD, MPA, MPH, Medical Director, Community Health and Prevention, Intermountain Healthcare, at (81) 442-3946.