Genetic characterization of measles viruses that circulated in Thailand from 1998 to 2008.

During the period between 1998 and 2008, 48 representative measles viruses (MeVs) circulating in Thailand were subjected to genetic characterization. Three genotypes, G2, D5, and D9 were detected. The results suggested that measles genotype D5, which has been circulating since at least 1998, is the endemic genotype in Thailand. Genotype G2 was detected between 1998 and 2001. In addition, almost all of the MeVs detected throughout the country in 2008 were genotype D9. This is the first report of genotype D9 in Thailand. This report provides important baseline data about measles genotypes in Thailand and this information will be needed to help verify measles elimination in Thailand.

Low Measles Seropositivity Rate among Thai Adolescents in the Thai National Immunization Program.

To achieve the goal of measles elimination, herd immunity with 95% seroprotection in the community is required. This study aimed to describe the measles seropositivity rate among Thai children and adolescents. A cross-sectional study was conducted among children aged 3−18 years in Bangkok and its suburbs. Measles IgG antibodies were measured using a EUROIMMUN enzyme-linked immunosorbent assay kit. Seropositivity is defined as a measles IgG titer of ≥200 IU/L, due to a correlation with a >85% positive rate with a plaque reduction neutralizing titer of >120. Factors associated with seropositivity were analyzed using logistic regression analysis. From May to July 2020, 570 children with a median (IQR) age of 11.7 (9.4−14.8) years were enrolled. The geometric mean titer (GMT) of anti-measles IgG was 281 IU/L (95% CI; 257−306). The proportion of children with seropositivity was inversely correlated with age; 3−5 years 85.3%, 6−9 years 72.5%, 10−14 years 50.7%, and 15−18 years 56.3%. Adolescents aged 10−18 years had a lower measles seropositivity rate compared with young children; aOR 0.29 (95% CI 0.17−0.48). Only half of the adolescents who received two doses of measles-containing vaccine maintained measles IgG above the seropositive level. A measles booster dose for young adults may be needed to achieve the measles elimination goal.

Immunogenic response in obese patients undergoing rabies post-exposure prophylaxis with combined equine rabies immunoglobulin and rabies vaccination.

BACKGROUND: Obesity is a risk factor for increased morbidity and mortality associated with many vaccine preventable infectious diseases such as influenza. Moreover, higher volume of passive rabies immunoglobulin (RIG) due to weight based dosing might suppress vaccine-induced immune responses in obese patients. This study aimed to evaluate the effect of obesity on humoral immune responses to combined equine RIG and rabies vaccine treatment among patients with WHO category III exposure to a rabies suspected animal. METHODS: A single centre, prospective, open-labelled study among WHO category III rabies exposed patients was conducted to compare serum rabies virus neutralizing antibody (RVNA) responses measured by rapid fluorescent focus inhibition test between obese (body mass index, BMI > 30 kg/m2) and control (BMI < 25 kg/m2) patients after combined immunization with equine rabies immunoglobulin and purified chick-embryo cell rabies vaccine for post exposure prophylaxis treatment. RESULTS: Post-vaccination geometric mean titer (GMT) of RVNA concentrations between two groups at day 7 were 0.33 (95% CI: 0.23, 0.46) vs 0.39 (95% CI: 0.27, 0.55), 4.61 (95% CI: 3.20, 6.63) vs 3.78 (95% CI: 2.77, 5.16) at day 14, and 7.45 (95% CI: 5.86, 9.49) vs 5.93 (95%CI: 4.46-7.90) at day 28 for obese and control patients, respectively. There was no statistically significant difference of RVNA GMT between two groups. Seroconversion to at least adequate concentration (RVNA titer ≥0.5 IU/mL) rates were 34% at day 7 and 100% at days 14 and 28 in both groups. There were no immediate hypersensitivity reaction and no serious adverse events observed during the study period. CONCLUSIONS: There was no evidence of immunosuppression of antibodies' responses in obese patients. Combined ERIG and rabies virus vaccination for post exposure treatment is safe.