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Need for improved vaccine safety surveillance
Vaccine 19 (2001) 1004 www.elsevier.com/locate/vaccine
Letter to the Editor
Need for improved vaccine safety surveillance Vaccines are administered mostly to healthy individuals. In industrialized countries, where risk of wild pollovirus infection is low and oral polio vaccine (OPV) is still routinely administered (e.g. Japan), adequate continuous monitoring of the safety of OPV is essential for appropriate risk-benefit policy decisions and maintaining public confidence in immunizations. In Japan, a two dose OPV schedule is routinely given to children 3–90 months of age with completeness maintained at \90%. Public vaccine providers conduct mass OPV immunization in every spring and fall. Japan is highly populated country (approximately 330 persons per square kilometre), and herd immunity by mass OPV immunization has contributed to elimination of either indigenous or imported poliomyelitis since 1981. In April 2000, a case of acute flaccid paralysis in a 13 months old boy and a fatal encephalitis case in a 38 months old girl were reported from Fukuoka Prefecture after both received OPV from the same lot c 39 produced by Japan polio institute during a mass immunization campaign. The paralysis case was concluded due to vaccine associated polio paralysis (VAPP), but etiology of the fatal encephalitis case remained unknown, although experts concluded that poliovirus is not cause of death. On May 16, 2000, the Japanese Ministry of Health and Welfare (MHW) announced concerns about the safety of lot c39 OPV and suspended mass immunization. Concurrently on May 15, 37 years old father in Miyazaki Prefecture developed quadriplegia after his 10 months old daughter received the same lot OPV MHW’s appointed experts reviewed 10 neurological adverse events after OPV reported to the Ministry’s active surveillance, but OPV was not attributable to any events. They assured its safety and immunization was restarted on June 7. Various issues concerning polio immunization strategies in Japan have been vigorously debated, in terms of immunization schedule, type of vaccine (live vs. inactivated), effects of simultaneous vaccination, and effectiveness of mass OPV immunization where child population is decreasing. The MHW announced that reporting rate of vaccinees’ VAPP and secondary VAPP are one in 4.4
million dose and one in 5.8 million dose, respectively. These figures are remarkably different from data from US [1]. Initial inactivated polio vaccine (IPV) followed by OPV will decrease VAPP 50–75% [2], but the need for more injections and weak herd immunity by IPV may compromise current high vaccination rate and community protection against invasion of the wild pollovirus [3]. In order to better clarify the concerns on rare vaccine risks in an era of elimination or near elimination of vaccine-preventable disease, vaccine safety surveillance is crucial. In Japan, the National Adverse Reaction Reporting System (NARRS) receives the VAPP cases of vaccinees only, so that the secondary VAPP case in Miyazaki was reported to the National Infectious Disease Surveillance System. These surveillance systems should be integrated and improved in a national vaccine safety monitoring system where new safety concerns can be addressed in a timely and scientifically rigorous manner by record linkage systems such as Vaccine Safety Datalink (VSD) [4]. Each national vaccine safety monitoring system should be standardized globally, respecting variation of vaccination schedule and vaccine type in the nation. References [1] Centers for Disease Control and Prevention. Poliomyelitis Prevention in the United States, MMWR, 2000; 49 (RR05); 1 –22. [2] Plotkin SA. Developed countries should use inactivated polio vaccine for the prevention of poliomyelitis. Medical Virology 1997;7:75 – 81. [3] Henderson DA. Developed countries should not use inactivated polio vaccine for the prevention of poliomyelitis. Medical Virology 1997;7:83 – 6. [4] Chen RT, DeStefano F, Davis RL, Jackson LA, Thompson RS, Mullooly JP, Black SB, Shinefield HR, Vadheim CM, Ward JI, Marcy SM. The Vaccine Safety Datalink: immunization research in health maintenance organizations in the USA. Bull World Health Organization 2000;78(2):186– 94.
0264-410X/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 4 - 4 1 0 X ( 0 0 ) 0 0 3 1 8 - 2
Hiroshi Takahashi Infectious Disease Sur6eillance Centre National Institute of Infectious Diseases Toyama 1 -23 -1 Shinjuku-ku, Tokyo 162 -8640 Japan E-mail address: [email protected]
Letter to the Editor
Need for improved vaccine safety surveillance Vaccines are administered mostly to healthy individuals. In industrialized countries, where risk of wild pollovirus infection is low and oral polio vaccine (OPV) is still routinely administered (e.g. Japan), adequate continuous monitoring of the safety of OPV is essential for appropriate risk-benefit policy decisions and maintaining public confidence in immunizations. In Japan, a two dose OPV schedule is routinely given to children 3–90 months of age with completeness maintained at \90%. Public vaccine providers conduct mass OPV immunization in every spring and fall. Japan is highly populated country (approximately 330 persons per square kilometre), and herd immunity by mass OPV immunization has contributed to elimination of either indigenous or imported poliomyelitis since 1981. In April 2000, a case of acute flaccid paralysis in a 13 months old boy and a fatal encephalitis case in a 38 months old girl were reported from Fukuoka Prefecture after both received OPV from the same lot c 39 produced by Japan polio institute during a mass immunization campaign. The paralysis case was concluded due to vaccine associated polio paralysis (VAPP), but etiology of the fatal encephalitis case remained unknown, although experts concluded that poliovirus is not cause of death. On May 16, 2000, the Japanese Ministry of Health and Welfare (MHW) announced concerns about the safety of lot c39 OPV and suspended mass immunization. Concurrently on May 15, 37 years old father in Miyazaki Prefecture developed quadriplegia after his 10 months old daughter received the same lot OPV MHW’s appointed experts reviewed 10 neurological adverse events after OPV reported to the Ministry’s active surveillance, but OPV was not attributable to any events. They assured its safety and immunization was restarted on June 7. Various issues concerning polio immunization strategies in Japan have been vigorously debated, in terms of immunization schedule, type of vaccine (live vs. inactivated), effects of simultaneous vaccination, and effectiveness of mass OPV immunization where child population is decreasing. The MHW announced that reporting rate of vaccinees’ VAPP and secondary VAPP are one in 4.4
million dose and one in 5.8 million dose, respectively. These figures are remarkably different from data from US [1]. Initial inactivated polio vaccine (IPV) followed by OPV will decrease VAPP 50–75% [2], but the need for more injections and weak herd immunity by IPV may compromise current high vaccination rate and community protection against invasion of the wild pollovirus [3]. In order to better clarify the concerns on rare vaccine risks in an era of elimination or near elimination of vaccine-preventable disease, vaccine safety surveillance is crucial. In Japan, the National Adverse Reaction Reporting System (NARRS) receives the VAPP cases of vaccinees only, so that the secondary VAPP case in Miyazaki was reported to the National Infectious Disease Surveillance System. These surveillance systems should be integrated and improved in a national vaccine safety monitoring system where new safety concerns can be addressed in a timely and scientifically rigorous manner by record linkage systems such as Vaccine Safety Datalink (VSD) [4]. Each national vaccine safety monitoring system should be standardized globally, respecting variation of vaccination schedule and vaccine type in the nation. References [1] Centers for Disease Control and Prevention. Poliomyelitis Prevention in the United States, MMWR, 2000; 49 (RR05); 1 –22. [2] Plotkin SA. Developed countries should use inactivated polio vaccine for the prevention of poliomyelitis. Medical Virology 1997;7:75 – 81. [3] Henderson DA. Developed countries should not use inactivated polio vaccine for the prevention of poliomyelitis. Medical Virology 1997;7:83 – 6. [4] Chen RT, DeStefano F, Davis RL, Jackson LA, Thompson RS, Mullooly JP, Black SB, Shinefield HR, Vadheim CM, Ward JI, Marcy SM. The Vaccine Safety Datalink: immunization research in health maintenance organizations in the USA. Bull World Health Organization 2000;78(2):186– 94.
0264-410X/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 4 - 4 1 0 X ( 0 0 ) 0 0 3 1 8 - 2
Hiroshi Takahashi Infectious Disease Sur6eillance Centre National Institute of Infectious Diseases Toyama 1 -23 -1 Shinjuku-ku, Tokyo 162 -8640 Japan E-mail address: [email protected]