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Causality assessment of serious neurologic adverse events following 2009 H1N1 vaccinationstar, open
S. Elizabeth Williamsa, Corresponding Author Contact Information, E-mail The Corresponding Author, Barbara A. Pahudb, 1, Claudia Vellozzic, Peter D. Donofrioa, Cornelia L. Dekkerb, Neal Halseyd, Nicola P. Kleine, Roger P. Baxtere, Colin D. Marchantf, Philip S. LaRussag, Elizabeth D. Barnettf, Jerome I. Tokarsc, Brian E. McGeeneyf, Robert C. Sparksa, Laurie L. Aukese, Kathleen Jakobg, Silvia Coronelf, James J. Sejvarc, Barbara A. Sladec and Kathryn M. Edwardsa
a Vanderbilt Vaccine Research Program, Vanderbilt University Medical Center, 1161 21st Ave. So. CCC 5323 MCN, Nashville, TN, United States
b Division of Pediatric Infectious Diseases, Stanford University School of Medicine, 300 Pasteur Drive, Room G312, Stanford, CA, United States
c Clinical Immunization Safety Assessment (CISA) Network, Immunization Safety Office, Division of Healthcare Quality and Promotion (DHQP), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Office of Infectious Diseases (OID), Centers for Disease Control and Prevention, Building 20, 1600 Clifton Road NE MS-D26, Atlanta, GA, United States
d Johns Hopkins University, Department of International Health, Disease Prevention and Control Program, Bloomberg School of Public Health, 615 North Wolfe Street, Room W5041, Baltimore, MD, United States
e Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, 16th Floor, Oakland, CA, United States
f Boston Medical Center, 670 Albany Street, 6th Floor, Suite 601, Boston, MA, United States
g Columbia University Medical Center, Division of Pediatric Infectious Diseases, 630 West 168th Street, P&S 3-435, New York City, NY, United States
Received 28 April 2011;
revised 18 August 2011;
accepted 22 August 2011.
Available online 3 September 2011.
Abstract
Background
Adverse events occurring after vaccination are routinely reported to the vaccine adverse event reporting system (VAERS). We studied serious adverse events (SAEs) of a neurologic nature reported after receipt of influenza A (H1N1) 2009 monovalent vaccine during the 2009?2010 influenza season. Investigators in the clinical immunization safety assessment (CISA) network sought to characterize these SAEs and to assess their possible causal relationship to vaccination.
Methods
Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) physicians reviewed all SAE reports (as defined by the Code of Federal Regulations, 21CFR?314.80) after receipt of H1N1 vaccine reported to VAERS between October 1, 2009 and March 31, 2010. Non-fatal SAE reports with neurologic presentation were referred to CISA investigators, who requested and reviewed additional medical records and clinical information as available. CISA investigators assessed the causal relationship between vaccination and the event using modified WHO criteria as defined.
Results
212 VAERS reports of non-fatal serious neurological events were referred for CISA review. Case reports were equally distributed by gender (50.9% female) with an age range of 6 months to 83 years (median 38 years). The most frequent diagnoses reviewed were: Guillain?Barr? Syndrome (37.3%), seizures (10.8%), cranial neuropathy (5.7%), and acute disseminated encephalomyelitis (3.8%). Causality assessment resulted in classification of 72 events as ?possibly? related (33%), 108 as ?unlikely? related (51%), and 20 as ?unrelated? (9%) to H1N1 vaccination; none were classified as ?probable? or ?definite? and 12 were unclassifiable (6%).
Conclusion
The absence of a specific test to indicate whether a vaccine component contributes to the pathogenesis of an event occurring within a biologically plausible time period makes assessing causality difficult. The development of standardized protocols for providers to use in evaluation of adverse events following immunization, and rapid identification and follow-up of VAERS reports could improve causality assessment.
Highlights
► We reviewed 212 neurological SAEs after H1N1 vaccine reported to VAERS. ► We applied modified WHO causality criteria to case reports. ► The most frequent diagnoses were GBS (37%) and seizure (11%). ► Causal assessment resulted in 72 possible, 108 unlikely, and 20 unrelated to vaccine.
http://www.sciencedirect.com/science/article/pii/S0264410X11013636
S. Elizabeth Williamsa, Corresponding Author Contact Information, E-mail The Corresponding Author, Barbara A. Pahudb, 1, Claudia Vellozzic, Peter D. Donofrioa, Cornelia L. Dekkerb, Neal Halseyd, Nicola P. Kleine, Roger P. Baxtere, Colin D. Marchantf, Philip S. LaRussag, Elizabeth D. Barnettf, Jerome I. Tokarsc, Brian E. McGeeneyf, Robert C. Sparksa, Laurie L. Aukese, Kathleen Jakobg, Silvia Coronelf, James J. Sejvarc, Barbara A. Sladec and Kathryn M. Edwardsa
a Vanderbilt Vaccine Research Program, Vanderbilt University Medical Center, 1161 21st Ave. So. CCC 5323 MCN, Nashville, TN, United States
b Division of Pediatric Infectious Diseases, Stanford University School of Medicine, 300 Pasteur Drive, Room G312, Stanford, CA, United States
c Clinical Immunization Safety Assessment (CISA) Network, Immunization Safety Office, Division of Healthcare Quality and Promotion (DHQP), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Office of Infectious Diseases (OID), Centers for Disease Control and Prevention, Building 20, 1600 Clifton Road NE MS-D26, Atlanta, GA, United States
d Johns Hopkins University, Department of International Health, Disease Prevention and Control Program, Bloomberg School of Public Health, 615 North Wolfe Street, Room W5041, Baltimore, MD, United States
e Kaiser Permanente Vaccine Study Center, 1 Kaiser Plaza, 16th Floor, Oakland, CA, United States
f Boston Medical Center, 670 Albany Street, 6th Floor, Suite 601, Boston, MA, United States
g Columbia University Medical Center, Division of Pediatric Infectious Diseases, 630 West 168th Street, P&S 3-435, New York City, NY, United States
Received 28 April 2011;
revised 18 August 2011;
accepted 22 August 2011.
Available online 3 September 2011.
Abstract
Background
Adverse events occurring after vaccination are routinely reported to the vaccine adverse event reporting system (VAERS). We studied serious adverse events (SAEs) of a neurologic nature reported after receipt of influenza A (H1N1) 2009 monovalent vaccine during the 2009?2010 influenza season. Investigators in the clinical immunization safety assessment (CISA) network sought to characterize these SAEs and to assess their possible causal relationship to vaccination.
Methods
Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) physicians reviewed all SAE reports (as defined by the Code of Federal Regulations, 21CFR?314.80) after receipt of H1N1 vaccine reported to VAERS between October 1, 2009 and March 31, 2010. Non-fatal SAE reports with neurologic presentation were referred to CISA investigators, who requested and reviewed additional medical records and clinical information as available. CISA investigators assessed the causal relationship between vaccination and the event using modified WHO criteria as defined.
Results
212 VAERS reports of non-fatal serious neurological events were referred for CISA review. Case reports were equally distributed by gender (50.9% female) with an age range of 6 months to 83 years (median 38 years). The most frequent diagnoses reviewed were: Guillain?Barr? Syndrome (37.3%), seizures (10.8%), cranial neuropathy (5.7%), and acute disseminated encephalomyelitis (3.8%). Causality assessment resulted in classification of 72 events as ?possibly? related (33%), 108 as ?unlikely? related (51%), and 20 as ?unrelated? (9%) to H1N1 vaccination; none were classified as ?probable? or ?definite? and 12 were unclassifiable (6%).
Conclusion
The absence of a specific test to indicate whether a vaccine component contributes to the pathogenesis of an event occurring within a biologically plausible time period makes assessing causality difficult. The development of standardized protocols for providers to use in evaluation of adverse events following immunization, and rapid identification and follow-up of VAERS reports could improve causality assessment.
Highlights
► We reviewed 212 neurological SAEs after H1N1 vaccine reported to VAERS. ► We applied modified WHO causality criteria to case reports. ► The most frequent diagnoses were GBS (37%) and seizure (11%). ► Causal assessment resulted in 72 possible, 108 unlikely, and 20 unrelated to vaccine.
http://www.sciencedirect.com/science/article/pii/S0264410X11013636