Status of residual IgG diphtheria antitoxin among people aged 5 - 40 years in Khanh Hoa province and prevention measures

Abstract

Diphtheria is a contagious and potentially fatal disease caused by the Corynebacterium diphtheriae bacteria’s toxin. In recent years, diphtheria outbreaks have appeared in some provinces in Vietnam’s Central and Highland regions. The study aimed to describe the current status of residual IgG diphtheria antitoxin among people aged 5 - 40 years in Khanh Hoa province and propose measures to prevent a diphtheria epidemic. The study was conducted on 1,195 subjects from 08 districts/cities of Khanh Hoa province from September 2021 to February 2023. Enzyme-linked immunosorbent assay (ELISA) was used to quantify the concentration of IgG diphtheria antitoxin in sera. The results showed that the percentage of people with adequate or long-term anti-diphtheria antibody levels was low (26.69%). The age group 5 - 10 has the highest average geometric mean concentration (GMC) - at an adequate protection level of 0.14IU/ml (except for the 5 – 10 year age group in Khanh Son district). The GMC fell to a partially protective level (< 0.1IU/ml) in most of the older age groups in all study sites. Recommended diphtheria prevention measures for Khanh Hoa province include organizing booster vaccination campaigns for at-risk age groups and areas; maintaining a high rate of regular vaccination with diphtheria toxoid-containing vaccines according to the vaccination schedule of the National Expanded Program on Immunization, giving booster vaccinations to the age group over 10 when there is a risk of an outbreak, strengthening health education on disease prevention.