• Journal of agricultural medicine and community health
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• v.47 no.2
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• pp.61-66
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• 2022

Objectives: In the epidemiology of communicable diseases, the term epidemic period, also referred to as "wave" is often used in the general and academic milieu. A wave refers to a natural pattern of increase in the number of sick individuals, a defined peak, and then a decline in the number of cases. It implies a pattern of peaks and valleys after a particular peak is taken. The idea of epidemic waves is a useful tool for predicting the course as well as helping to accurately describe an epidemic. However, in many domestic and foreign news as well as in various research results in Korea, most of the reports either had no standard, were inaccurate, had a questionable classification of the period of the epidemic, or the basis for classification of a given wave was not presented. Methods: The author reviewed and organized related literature with epidemic wave. The author made several suggestions of an epidemic wave as follows. Results: To start with, it should be based on the number of incident cases in consideration of the size of the outbreak, then the period from the bottom to the peak and then reaching the next bottom; also, the period over a certain scale based on the number of incident cases; and the period according to the change in the major infection type (mutation-dominant species). In addition, according to the period of change in the vaccination rate (formation of herd immunity), as well as the content and duration of the intervention, that is, classification according to the applied quarantine stage. Furthermore, the classification of epidemic periods by the time-dependent reproduction number or time-varying reproduction number (Rt), and lastly the application of mathematical methodology. Conclusions: Therefore, classifying the epidemic period into generally known and accepted time frames is considered to be a very important task for future research analysis and development of intervention strategies.

• Pediatric Infection and Vaccine
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• v.6 no.2
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• pp.245-252
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• 1999

Purpose : The aim of this study is to determine the age-specific seropositivity and the level of measles specific IgG in adults and to evaluate herd immunity to measles in Korea, the measles specific IgG were measured from the sera of adults over ages of 20 in Korea. Methods : 156 sera were collected from 156 out-patients over ages 20, who had visited clinical laboratory from June to July in 1997 at Korea University Ansan Hospital. The histories of natural measles or vaccination were not undertaken. Measles specific IgG titers were measured using ELISA method($SIA^{TM}$ Measles IgG Kit Co. St. Louis. Mo). Results : The results obtained from this study were as follows. 1) The seropositivity of measles specific IgG in adults was 94.9%. And there were no significant differences in their age and gender. 2) The mean measles-specific IgG titer was $238{\pm}84AU/mL$. And there were no significant differences in age and gender, except significant lower in 4th decades than other age groups. And there were no significant correlations between age and measles specific IgG level. Conclusion : In conclusion, a seropositivity of in adults was 94.9% which was higher than that of adolescents(91.2% in previous study), and antibody level was similar with adolescents. The herd immunity of the adults were considered to enough for protecting the transmission of measles in the community. For the eradication of measles in Korea, more efforts will be required to increase the vaccine coverage rate in children and adolescents.

• Clinical and Experimental Pediatrics
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• v.45 no.8
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• pp.980-986
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• 2002

Purpose : Although the number of patients with measles have dramatically decreased since the introduction of measles vaccines in 1965, measles outbreaks have occurred periodically every 4-6 years during the 1990s(1989-1990 and 1993-1994). During 2000-2001, measles prevailed all over the country again. A characteristic of current epidemics is that the majority of affected population was infants and school-aged children. This study was designed to analyze the epidemic and clinical features of measles prevalence during 2000-2001 and to find ways to overcome vaccination failure. Methods : We reviewed the records of 59 patients with mealses admitted in the Pediatric Department of Pusan National University Hospital from January 2000 to October 2001 for patient's age, month of admission, history of vaccination, clinical features and complications. Antibody titers of measles-specific IgM and IgG were measured by enzyme immunoassay. Results : The epidemic show two peaks in the age distribution. Forty three patients(72.9%) were under 2-years of age and 14 patients(23.7%) were over 5-years of age. Outbreaks had high incidence in July to August, 2000 and March to April, 2001, then faded away after July, 2001. Vaccinated group comprised 30.5% and unvaccinated group comprised 69.5% and their mean age was $9.25{\pm}4.27$ years old and $0.95{\pm}0.30$ years old respectively. Positive rate of IgM was 86.7% in vaccinated group and 90.3% in unvaccinated group. This means there was primary vaccine failure; 13 cases of 15 vaccinated patients were positive in IgM antibody. During the prevalence, two patients died with mealses complication. One of them was immunocompromised. Conclusion : To prevent another prevalence of measles in the future, we must enhance revaccination at ages 4-6 and check vaccination status when children enter elementary school. These will produce over 95% of herd immunity, with catch-up MMR vaccination which has been completed already.