Varicella emergency vaccination seemed instrumental in declining chickenpox incidente in Guangzhou, Southern China

March 19, 2013

Dear Editor

Chickenpox (Varicella zoster) is an acute common disease caused by the varicella zoster virus (VZV)⁹. It is highly communicable with an infection rate of 90% in close contacts³. As the largest trading city in southern China with over 7.94 million registered inhabitants and 4.76 million floating population, Guangzhou is located in the southern subtropical. Chickenpox is becoming an extremely common airborne and contact transmission disease, and public health authorities are concerned about its increased incidence.

Chickenpox is not a national reportable disease in China, so it is impossible to correctly evaluate incidence rate of population. However, since 1995, Guangzhou local government has legislated and included chickenpox into local reportable disease inventory. That means like the other national reportable disease, physicians who diagnose suspected or confirmed cases must report these cases to Guangzhou Centers for Disease Control and Prevention (GZCDC) through the National Notifiable Disease Report System (NNDRS). For a patient's illness to meet the case definition for chickenpox the clinical signs (characteristic rash, fever, nausea, hyporexia, aching muscles, and headache) must be present and samples should be taken for laboratory confirmation (4-fold rise in antibody titer, antigen detected in blood, or genetic material detected by PCR).

Different from the immunization strategy of measles, polio, et al., chickenpox is not incorporated into Expanded Program on Immunization (EPI) in China; it is administered as part of the voluntary vaccination program. Although routine childhood varicella vaccination has been strongly recommended by the government, the incidence of chickenpox in Guangzhou is increasing annually. From 2006 to 2011, the average incidence of chickenpox was 132.89, 143.68, 149.22, 168.26, 179.73, and 182.35 per 100,000 inhabitants respectively. A much higher incidence rate was shown than that of Japan⁸, Korea¹ and the other Asian regions,²,⁴,¹⁰ .

In 2012, Guangzhou conducted a varicella emergency vaccination program (VEVP): once the chickenpox outbreak was detected, a free dose varicella vaccination was used immediately to immunize all contacts exposed to the same grade, room, family, office, building and other probable risk areas for the patients. The injection work was required to be completed in three days. As result, the one-year implementation of VEVP seemed to play a positive and effective role in the mitigation of chickenpox. According to the NNDRS data, statistics showed that the incidence rate of chickenpox reported in 2012 showed the first declining trend. Compared to the average incidence rate of the past six years, the incidence rate in 2012 decreased by 30.19% (159.35 per 100000 VS. 111.45 per 100000) (Fig. 1).

Fig. 1
Annually incidence rate of chickenpox in Guangzhou, South China, 2006-2012.

The emergency vaccination has been proved effective in many diseases. For example, LI et al. reported that emergency vaccination could effectively alleviate highly pathogenic porcine reproductive and respiratory syndrome virus (HPPRRSV) infection during experimental contact exposure⁵. In England, this strategy was also evaluated for efficacy and feasibility to control rabies in hypothetical rural areas immediately after a disease outbreak⁷.

Taken together, Universal varicella vaccination program is unavailable to public in previous China. A major obstacle is the high cost of this vaccine, which is 10 times more expensive than the rubella vaccine and 75 times more expensive than the measles vaccine in China⁶. We reported varicella emergency vaccination as useful and an instrumental measure to decline chickenpox incidence in Guangzhou, southern China. This information will be used to establish strategies for the prevention of the increasing chickenpox in other regions or countries where the financial backing is not big enough to support a universal varicella vaccination and where the varicella vaccination remained of low coverage.

Tiegang LI
Guangzhou Center for Disease Control and Prevention, Guangdong Province, 510440, China. E-mail: [e-mail]

REFERENCES

• ¹
  Cho SB, Oh SH, Ahn BK, Kim HS, Park JM, Lee JH, et al. Incidence of chickenpox in young South Korean soldiers and correlation with atopic dermatitis. Clin Exp Dermatol. 2009;34:668-71.
• ²
  Khaleel HA, Abdelhussein HM. Clinical epidemiology of chickenpox in Iraq from 2007-2011. Glob J Health Sci. 2012;5:180-6.
• ³
  Lee BR, Feaver SL, Miller CA, Hedberg CW, Ehresmann KR. An elementary school outbreak of varicella attributed to vaccine failure: policy implications. J Infect Dis. 2004;190:477-83.
• ⁴
  Lin YH, Huang LM, Chang IS, Tsai FY, Chang LY. Disease burden and epidemiological characteristics of varicella in Taiwan from 2000 to 2005. J Microbiol Immunol Infect. 2009;42:5-12.
• ⁵
  Li X, Qiu L, Yang Z, Dang R, Wang X. Emergency vaccination alleviates highly pathogenic porcine reproductive and respiratory syndrome virus infection after contact exposure. BMC Vet Res. 2013;9:26.
• ⁶
  Ma H, Fontaine R. Varicella outbreak among primary school students--Beijing, China, 2004. MMWR Morb Mortal Wkly Rep. 2006;55(Suppl 1):39-43.
• ⁷
  Singer A, Smith GC. Emergency rabies control in a community of two high-density hosts. BMC Vet Res. 2012;8:79.
• ⁸
  Toyama N, Shiraki K. Epidemiology of herpes zoster and its relationship to varicella in Japan: a 10-year survey of 48,388 herpes zoster cases in Miyazaki prefecture. J Med Virol. 2009;81:2053-8.
• ⁹
  Wood MJ. History of varicella zoster virus. Herpes. 2000;7:60-5.
• ¹⁰
  Zhang Y, Zang GQ, Tang ZH, Yu YS. Universal varicella vaccination needs to be high on the agenda in China. Rev Inst Med Trop Sao Paulo. 2012;54:237-8.

Publication Dates

• Publication in this collection
  May-Jun 2013