The seroprevalence, waning rate, and protective duration of anti-diphtheria toxoid IgG antibody in Nha Trang, Vietnam

Kitamura, Noriko; Le, Lien Thuy; Le, Thao T.; Nguyen, Hien-Anh Thi; Edwards, Tansy; Madaniyazi, Lina; Bui, Minh Xuan; Thai, Hung; Dang, Duc-Anh; Toizumi, Michiko; Fine, Paul E. M.; Yoshida, Lay-Myint

doi:10.1016/j.ijid.2022.01.025

Cited by 7 publications

(6 citation statements)

References 29 publications

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“…We previously measured the duration of protective immunity using 2-year cohort data in a well-vaccinated community in Vietnam. 45 This study showed that IgG remains above 0.1 IU/ml for 4.3 years (95%CI:3.5,5.3) after the fourth dose of DTP was given at 18 months of age. This result supports the recommendation for a school-entry booster dose.…”

Section: Discussionmentioning

confidence: 63%

Waning rate of immunity and duration of protective immunity against diphtheria toxoid as a function of age and number of doses: Systematic review and quantitative data analysis

Kitamura

Bahkali

Chem

et al. 2022

Human Vaccines & Immunotherapeutics

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Although the burden of diphtheria has declined greatly since the introduction of vaccines, sporadic outbreaks continue to be reported. WHO recommends booster doses after a primary series, but questions remain about the optimal interval between these doses. We conducted a systematic review and quantitative data analysis to quantify the duration of protective immunity after different numbers of doses. Fifteen cross-sectional seroprevalence studies provided data on geometric mean concentration (GMC). Single-year age-stratified GMCs were analyzed using a mixed-effect linear regression model with a random intercept incorporating the between-country variability. GMC was estimated to decline to 0.1 IU/ml in 2.5 years (95% CI: 0.9–4.0), 10.3 years (95% CI: 7.1–13.6), and 25.1 years (95% CI: 7.6–42.6) after receiving three, four and five doses, respectively. The results drawn from cross-sectional data collected in countries with different epidemiologies, vaccines, and schedules had several limitations. However, these analyses contribute to the discussion of optimal timing between booster doses of diphtheria toxoid-containing vaccine.

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Section: Discussionmentioning

confidence: 63%

Waning rate of immunity and duration of protective immunity against diphtheria toxoid as a function of age and number of doses: Systematic review and quantitative data analysis

Kitamura

Bahkali

Chem

et al. 2022

Human Vaccines & Immunotherapeutics

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“…Nevertheless, 50% of the population >17 years of age were susceptible, which explains why all age groups have been recently affected by diphtheria ( 4 ). A school-entry booster dose will be recommended to prevent future cases because the infant immunization program appeared to create low immunity in school age children ( 15 ). Conversely, low immunity in preschool age children would be another reason for the recent epidemic in Quang Ngai Province.…”

Section: Discussionmentioning

confidence: 99%

“…We stratified age into 4 groups, 1–5, 6–17, 18–40, and 41–55 years of age; children attend primary through high school between the ages of 6 and 17 years in Vietnam. On the basis of previously obtained age-stratified seroprevalence in Vietnam ( 14 , 15 ), the required sample size for each age stratum was estimated to be 350, 400, 400, and 350, respectively, with 10% precision, a 3.5 design effect, and an 80% response rate.…”

Section: Methodsmentioning

confidence: 99%

“…Regarding the nonepidemic area, Nha Trang (city) in Khanh Hoa Province was selected because the population is well-vaccinated and has not reported any diphtheria cases since 2013. Moreover, the age-stratified seroprevalence data among persons 1–55 years of age were investigated in Nha Trang during 2017 ( 15 ). Therefore, we compared the immunity pattern of the population in Quang Ngai Province with that for Nha Trang.…”

Section: Methodsmentioning

confidence: 99%

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Seroepidemiology and Carriage of Diphtheria in Epidemic-Prone Area and Implications for Vaccination Policy, Vietnam

Kitamura¹,

Hoan²,

Hung³

et al. 2023

Emerg. Infect. Dis.

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D iphtheria is an infectious disease caused by toxigenic strains of Corynebacterium diphtheriae, C. ulcerans, and, rarely, C. pseudotuberculosis (1-3). Although the diphtheria toxoid vaccine contributed to a decrease in the number of diphtheria cases globally, the disease remains a threat to public health, particularly in South and Southeast Asia (4,5).Currently, the World Health Organization recommends 3 primary doses of the diphtheria-tetanuspertussis (DTP) vaccine in young infants (i.e., at 6, 10, and 14 weeks of age), followed by 3 booster doses at 12-23 months, 4-7 years, and 9-15 years of age, to protect all age groups. Nevertheless, many low-and middle-income countries have not introduced all booster doses.The Vietnamese Ministry of Health (MOH) first introduced DTP in 1981, targeting infants 2, 3, and 4 months of age. A booster dose targeting children 18 months of age was introduced during 2011 (6). Because of efforts in vaccination, reported diphtheria cases in Vietnam decreased to nearly zero by 2010. However, several small diphtheria outbreaks in remote districts in central and western Vietnam have been observed since 2013 (7).Supplemental immunization activities (SIAs), in which vaccination is delivered to all targeted persons regardless of their previous vaccination history, were conducted in the areas surrounding Quang Ngai Province when diphtheria cases were identified during 2013-2019 (8). However, most of the population of Quang Ngai Province has not been covered by SIAs as of October 2019. According to the national surveillance program, Quang Ngai Province reported 2 laboratory-confirmed cases in 2017-2018 and 47 in 2019-2020, among an estimated population of 1,231,697 (9). Among these cases, 36 (73%) cases were in school-age children (6-17 years of age). Among confirmed cases, 3 (6%) were fatal.Although national administrative coverage of 3 doses of DTP among infants has been maintained

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“…A total of 510 subjects aged 0–55 years were recruited by simple random sampling based on population census data, and serum samples were collected from the participants. The detailed survey method is reported elsewhere [21]. Of the 510 participants, 100 were randomly selected and recruited in 2019 to compare the TNT and ELISA methods.…”

Section: Methodsmentioning

confidence: 99%

Evaluation and validation of a commercial ELISA versus the in vitro toxin neutralization assay for determination of diphtheria anti-toxin in human serum

Kitamura

Endo

et al. 2023

Journal of Medical Microbiology

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Introduction. Diphtheria is a potentially life-threatening infection and remains endemic in many low- and middle-income countries (LMICs). A reliable, low-cost method for serosurveys in LMICs is warranted to estimate the accurate population immunity to control diphtheria. Hypothesis/Gap Statement. The correlation between the ELISA results against diphtheria toxoid and the gold standard diphtheria toxin neutralization test (TNT) values is poor when ELISA values are <0.1 IU ml−1, which results in inaccurate estimates of susceptibility in populations when ELISA is used for measuring antibody levels. Aim. To explore methods to accurately predict population immunity and TNT-derived anti-toxin titres from ELISA anti-toxoid results. Methodology. A total of 96 paired serum and dried blood spot (DBS) samples collected in Vietnam were used for comparison of TNT and ELISA. The diagnostic accuracy of ELISA measurement with reference to TNT was assessed by area under the receiver operating characteristic (ROC) curve (AUC) and other parameters. Optimal ELISA cut-off values corresponding to TNT cut-off values of 0.01 and 0.1 IU ml−1 were identified by ROC analysis. A method based on the multiple imputation approach was also applied to estimate TNT measurements in a dataset that only included ELISA results. These two approaches were then applied to ELISA results previously generated from 510 subjects in a serosurvey in Vietnam. Results. The ELISA results on DBS samples showed a good diagnostic performance compared to TNT. The cut-off values for ELISA measurement corresponding to the TNT cut-off values of 0.01 IU ml−1 were 0.060 IU ml−1 in serum samples, and 0.044 IU ml−1 in DBS samples. When a cut-off value of 0.06 IU ml−1 was applied to the 510 subject serosurvey data, 54 % of the population were considered susceptible (<0.01 IU ml−1). The multiple imputation-based approach estimated that 35 % of the population were susceptible. These proportions were much larger than the susceptible proportion estimated by the original ELISA measurements. Conclusion. Testing a subset of sera by TNT combined with ROC analysis or a multiple imputation approach helps to adjust ELISA thresholds or values to assess population susceptibility more accurately. DBS is an effective low-cost alternative to serum for future serological studies for diphtheria.

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The seroprevalence, waning rate, and protective duration of anti-diphtheria toxoid IgG antibody in Nha Trang, Vietnam

Cited by 7 publications

References 29 publications

Waning rate of immunity and duration of protective immunity against diphtheria toxoid as a function of age and number of doses: Systematic review and quantitative data analysis

Waning rate of immunity and duration of protective immunity against diphtheria toxoid as a function of age and number of doses: Systematic review and quantitative data analysis

Seroepidemiology and Carriage of Diphtheria in Epidemic-Prone Area and Implications for Vaccination Policy, Vietnam

Evaluation and validation of a commercial ELISA versus the in vitro toxin neutralization assay for determination of diphtheria anti-toxin in human serum

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