Skip Navigation
  • Text Size: A A A
  • Print
  • Email
  • Facebook
  • Tweet
  • Share
  • Print
  • Email
  • Facebook
  • Tweet
  • Share

Letter from the Chair to the Assistant Secretary for Health, RE: NVAC – April 23, 2010 Meeting

Howard K. Koh, M.D., M.P.H
Assistant Secretary for Health
Department of Health and Human Services
200 Independent Avenue, SW, Rm. 701-H
Washington DC 20201

RE: NVAC – April 23, 2010 Meeting

Dear Dr. Koh:

I am pleased to transmit to you a report on 2009 H1N1 Vaccine Safety that was adopted unanimously today by the National Vaccine Advisory Committee (NVAC) during its public teleconference meeting. The draft report (enclosure) was developed by the NVAC H1N1 Vaccine Safety Risk Assessment Working Group (VSRAWG) chaired by Dr. Marie McCormick.

Reports adopted by the NVAC normally are transmitted through the National Vaccine Program Office to the ASH as an attachment to a letter from the NVAC chair reporting on the discussion and recommendations of the NVAC meeting. However, the NVPO has requested that this report be transmitted quickly because the current interest in the H1N1 vaccination program.

To summarize, the NVAC endorses the VSRAWG's conclusion that the available data are adequate to assess the presence or absence of a safety signal related to H1N1 vaccine.  In addition, the NVAC endorses the VSRAWG’s findings in three areas:

  1. A potential weak signal between H1N1 vaccine exposure and Guillain-Barré syndrome (GBS) was initially detected in the Emerging Infections Program (EIP) data.  Additional analyses with updated information on estimates of vaccine coverage and accounting for variation in the estimation of vaccination coverage rates further weakened the signal.  The Working Group will continue to monitor these data including an updated analysis from the EIP with data from March (current data is through February).
  2. A weak signal between H1N1 vaccine exposure and Bell’s palsy emerged in two monitoring systems.  In one system, several analyses to examine this finding yielded inconsistent results with some comparisons providing support for the signal while others did not.
  3. A weak signal between H1N1 vaccine exposure and thrombocytopenia/idiopathic thrombocytopenic purpura emerged in three monitoring systems.  In these systems the cases are being reviewed to see if the diagnoses are valid.  More rigorous comparisons between cohorts with H1N1 vaccine exposure and other vaccines or no exposure are planned.

The NVAC endorses the VSRAWG’s conclusion that the evidence suggests a weak signal between receipt of H1N1 vaccine and the indicated adverse events that requires further validation, and that these results do not necessitate any other immediate response.

The NVAC endorses the VSRAWG’s recommendation that the federal government continue to monitor H1N1 vaccine safety as the body of evidence accumulates. Moreover, the NVAC recommends that the federal agencies and departments prepare and present analytic plans to assess the validity of the observations noted, define end-of-season analyses for adverse events, and conduct analyses across monitoring systems to have sufficient power to assess the effect of H1N1 exposure on relatively rare events and to assess the consistency of estimates across the different databases.

The VSRAWG will hold its next meeting on May 3, 2010 to review progress in further analyzing these weak signals.  The NVAC will hold its next public teleconference meeting on May 21, 2010 at which time it will receive an update from the VSRAWG.  The NVAC stands prepared to meet at any time as needed if the emerging data indicate a significant concern.

Please let me know if you have any questions.



Guthrie S. Birkhead, M.D., M.P.H.
Chair, National Vaccine Advisory Committee