Hae Ji Kang1, Young Woo Han1, Su Jin Kim1, You-Jin Kim1, A-Reum Kim1, Joo Ae Kim1, Hee-Dong Jung1, Hye Eun Eom2, Ok Park3, Sung Soon Kim4. 1. Division of Respiratory Viruses, Center for Infectious Diseases, National Institutes of Health, Korea Centers for Disease Control & Prevention, Cheongju-si, Chungbuk, Republic of Korea. 2. Division of Vaccine-Preventable Diseases Control and National Immunization Program, Centers for Disease Prevention, Korea Centers for Disease Control & Prevention, Cheongju-si, Chungbuk, Republic of Korea. 3. Division of Risk Assessment & International Cooperation, Centers for Emergency Operations, Korea Centers for Disease Control & Prevention, Cheongju-si, Chungbuk, Republic of Korea. 4. Division of Respiratory Viruses, Center for Infectious Diseases, National Institutes of Health, Korea Centers for Disease Control & Prevention, Cheongju-si, Chungbuk, Republic of Korea. Electronic address: sungskim63@gmail.com.
Abstract
BACKGROUND: In Korea, measles occurs mainly in infants <12months of age, who are unvaccinated. In addition, vaccine populations, including adolescents and young adults, can become infected though importation. Thus, the question arises whether the current level of herd immunity in Korea is now insufficient for protecting against measles infection. METHODS: Age-specific measles seroprevalence was evaluated by performing enzyme immunoassays and plaque reduction-neutralization tests on 3050 subjects aged 0-50years (birth cohort 1964-2014) and 480 subjects aged 2-30years (birth cohort 1984-2012). RESULTS: The overall seropositivity and measles antibody concentrations were 71.5% and 1366mIU/mL, respectively. Progressive decline in antibody levels and seropositivity were observed over time after vaccination in infants, adolescents, and young adults. The accumulation of potentially susceptible individuals in the population was confirmed by comparing data from 2010 and 2014 seroprevalence surveys. The statistical correlation between measles incidence and measles seronegativity was determined. CONCLUSIONS: Waning levels of measles antibodies with increasing time post-vaccination suggests that measles susceptibility is potentially increasing in Korea. This trend may be related to limitations of vaccine-induced immunity in the absence of natural boosting by the wild virus, compared to naturally acquired immunity triggered by measles infection. This study provides an important view into the current measles herd immunity in Korea.
BACKGROUND: In Korea, measles occurs mainly in infants <12months of age, who are unvaccinated. In addition, vaccine populations, including adolescents and young adults, can become infected though importation. Thus, the question arises whether the current level of herd immunity in Korea is now insufficient for protecting against measles infection. METHODS: Age-specific measles seroprevalence was evaluated by performing enzyme immunoassays and plaque reduction-neutralization tests on 3050 subjects aged 0-50years (birth cohort 1964-2014) and 480 subjects aged 2-30years (birth cohort 1984-2012). RESULTS: The overall seropositivity and measles antibody concentrations were 71.5% and 1366mIU/mL, respectively. Progressive decline in antibody levels and seropositivity were observed over time after vaccination in infants, adolescents, and young adults. The accumulation of potentially susceptible individuals in the population was confirmed by comparing data from 2010 and 2014 seroprevalence surveys. The statistical correlation between measles incidence and measles seronegativity was determined. CONCLUSIONS: Waning levels of measles antibodies with increasing time post-vaccination suggests that measles susceptibility is potentially increasing in Korea. This trend may be related to limitations of vaccine-induced immunity in the absence of natural boosting by the wild virus, compared to naturally acquired immunity triggered by measles infection. This study provides an important view into the current measles herd immunity in Korea.
Authors: Kyunghyun Song; Ju Mi Lee; Eun Ju Lee; Bo Ram Lee; Ji Young Choi; Jihee Yun; Se Na Lee; Mi Young Jang; Han Wool Kim; Han-Sung Kim; Song Mi Moon; Yong Kyun Kim Journal: Eur J Clin Microbiol Infect Dis Date: 2022-01-09 Impact factor: 3.267