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On-line version ISSN 1678-9946
Rev. Inst. Med. trop. S. Paulo vol.54 no.4 São Paulo July/Aug. 2012
LETTER TO THE EDITOR
Yi ZhangI, II; Guo-Qing ZangI; Zheng-Hao TangI; Yong-Sheng YuI
IDepartment of Infectious Diseases, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, P. R. China
IIMedical College of Soochow University, Suzhou, P. R. China
Shanghai, June 3rd, 2012
Varicella is highly contagious, with a clinical attack rate of 60%-90% following household exposure of susceptible individuals4. It was not a notifiable infectious disease in China, national data on incidence rate and statistics concerning hospitalizations and deaths attributable to varicella were not available until 2005. Since then, varicella has been required to be reported to the National Notifiable Diseases Reporting System (NNDRS). According to the data from NNDRS, the incidence of varicella in China is increasing annually. Thus, it is estimated that the national average incidence of varicella was 12.0, 20.6, 23.8, 24.1 and 24.3 per 100,000 inhabitants from 2006 to 2010 respectively11,12. However such incidence rates may be underestimated, the actual incidence rates should be much higher. A recent study of epidemiological data on varicella in Shanghai Zhabei district between 2005 and 2006 revealed that more than half of the outbreak cases were not reported to NNDRS3. The main reason for this is that the rate of missing reports on varicella from the medical institutions is extremely high3. Therefore, the varicella monitoring and reporting system in China needs to be improved.
Before introduction of the varicella vaccine, there were about four million cases of varicella annually in the United States, with an average of 11,000-13,500 hospitalizations and 100-150 deaths2,7. After implementation of the varicella vaccination program in 1995, varicella age-specific incidence rates significantly declined for all age groups6. During 1995-2005, in two US varicella active surveillance sites where high vaccine coverage was achieved in young children, the incidence of varicella among children aged 0-14 years declined by 90% and that among adults aged > 20 years declined by 74%6. In addition, varicella-related hospitalizations and deaths decreased substantially7. It has been demonstrated that one dose of varicella vaccine was 84.5% effective (median; mean 80.7%) in preventing all varicella and 100% effective (median and mean) in preventing severe varicella9.
Besides the United States, varicella vaccine has been licensed for the universal vaccination of children in a number of developed countries1. Furthermore, it has been expanding in Latin American countries, for example Brazil and Uruguay8. Nonetheless, varicella vaccination of children aged > 12 months has not been incorporated into the national or provincial childhood immunization schedules in China. A major obstacle is the high cost of this vaccine, which is 10 times more expensive than rubella vaccine and 75 times more expensive than measles vaccine in China5. Statistics showed that only 26.9% children < 12 years of age in Shanghai received varicella vaccine during 1999-200510.
In addition to having positive effects on disease prevention and control, mathematical models indicate that routine childhood vaccination against varicella may provide economic benefits for the individual and society1. A recent study suggested that the universal varicella vaccination program was worthwhile in China and the benefit-cost ratio of one dose of routine varicella vaccine was 4.1913. Assessment of the epidemiology of varicella and evidence for the effectiveness of varicella vaccination provide support for the routine childhood vaccination in China. Therefore, in our own opinion, China should make a decision on the implementation of the universal varicella vaccination program.
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10. Wu HY, Zhang AX, Ren H, Li YT. An epidemiological investigation on varicella vaccination among children in some areas of Shanghai (Chinese). Shanghai Yu Fang Yi Xue Za Zhi. (Shanghai Journal of Preventive Medicine). 2006;18:437-9. [ Links ]
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Department of Infectious Diseases, Shanghai Sixth People's Hospital
Shanghai Jiao Tong University, 600 Yishan Road, 200233 Shanghai, P. R. China
Phone: + 86 21 64369181-58673. Fax: + 86 21 24058384