Efficacy, safety, and immunogenicity of an inactivated, adjuvanted enterovirus 71 vaccine in infants and children: a multiregion, double-blind, randomised, placebo-controlled, phase 3 trial.

BACKGROUND: Children are susceptible to severe or fatal enterovirus 71 (EV71) infections. We aimed to evaluate the efficacy, safety, and immunogenicity of EV71vac, an aluminium phosphate-adjuvanted inactivated EV71 vaccine in children aged 2-71 months. METHODS: We did a randomised, double-blinded, placebo-controlled, phase 3 trial at five hospitals in Taiwan and two in Vietnam. Children aged 2-71 months were stratified by country and age, and randomly assigned (1:1) to receive two doses of EV71vac or placebo via intramuscular injection 56 days apart. Children aged 2-23 months received a third booster dose on day 366. The primary endpoint was the clinical efficacy of the total vaccinated cohort against EV71-associated diseases during the follow-up period, from 14 days after the second dose to when 15 cases of EV71 infections were confirmed in the per-protocol population. Our safety analysis included all participants who received at least one dose of EV71vac. This trial is registered with ClinicalTrials.gov, NCT03865238, and is complete. FINDINGS: Between April 23 and Dec 25, 2019, of 3663 children assessed, 3061 were randomly assigned, of whom 3049 were vaccinated: 1521 children in the EV71vac group and 1528 in the placebo group. By May 20, 2021, our primary efficacy analysis included 2959 children, with 1476 children in the EV71vac group and 1483 children in the placebo group. The vaccine efficacy of EV71vac was 96·8% (95% CI 85·5-100) against EV71 associated diseases (p<0·0001). The percentage of participants who reported solicited adverse events were similar in both groups: 865 (56·9%) in the EV71vac group and 852 (55·8%) in the placebo group. Almost all reported solicited adverse events were mild and self-limited. INTERPRETATION: EV71vac is safe, well-tolerated, and highly effective in preventing EV71 associated diseases in children aged 2-71 months. FUNDING: Medigen Vaccine Biologics and A+ Industrial Innovative R&D Program of the Ministry of Economic Affairs, Taiwan.

Seroprevalence of SARS-CoV-2 among high-density communities and hyper-endemicity of COVID-19 in Vietnam.

OBJECTIVE: To assess the magnitude of active and recovering COVID-19 patients among at-risk communities and to identify the factors associated with positive serology. METHODS: Four hundred and eighty-three close contacts of COVID-19 patients residing in Ho Chi Minh City, Vietnam, during the fourth wave of the COVID-19 epidemic (September and October 2021) were included. Five weeks after exposure to a COVID-19 patient, they underwent a serology test using the BIOSYNEX COVID-19 BSS kit. RESULTS: The median age of participants was 37 years. A total of 34.6% individuals presented at least one clinical symptom between the time of contact with the COVID-19 patient and inclusion in study. A total of 1.7% unvaccinated individuals tested positive for SARS-CoV-2 using real-time PCR, and 9.5% had evidence of recent infection (positive PCR and/or IgM). A further 26.7% unvaccinated individuals presented evidence of a past infection (positive IgG only). Socio-demographic characteristics, vaccination status and clinical symptoms were not associated with a positive IgM test. CONCLUSION: This is the first serosurvey conducted during the fourth wave of the epidemic in Vietnam. It revealed a seropositivity rate higher than in previous studies and confirmed the hyperendemicity of SARS-CoV-2. Testing using rapid serological tests proved to be a reliable, easy-to-use method and enabled a rapid estimation of the burden of COVID-19.

Carbapenemase Genes and Multidrug Resistance of Acinetobacter Baumannii: A Cross Sectional Study of Patients with Pneumonia in Southern Vietnam.

BACKGROUND: Acinetobacter baumannii (Ab) is an opportunistic bacterial pathogen found in hospital-acquired infections including nosocomial pneumonia, especially multidrug-resistant Ab. This study aims to survey the drug resistance profiles of Ab isolated from patients in Thong Nhat Dong Nai General Hospital and assess the relationship between genotypes and antibiotic resistance; Methods: Ninety-seven Ab strains isolated from 340 lower respiratory tract specimens among pneumonia patients were used to screen the most common local carbapenemase genes. Antimicrobial susceptibility testing results and demographic data were collected and minimum inhibitory concentrations (MIC) of colistin were also determined; Results: Over 80% and 90% of Ab strains were determined as carbapenem-resistant and multidrug-resistant (MDR), respectively. Most of the strains carried carbapenemase genes, including blaOXA-51, blaOXA-23-like, blaOXA-58-like, and blaNDM-1, with proportions of 97 (100%), 76 (78.4%), 10 (10.3%), 6 (6.2%), respectively. Amongst these genes, blaOXA-23-like was the only gene which significantly influenced the resistance (p < 0.0001); and Conclusions: The severity of Ab antibiotic resistance is urgent and specifically related to carbapenemase encoding genes. Therefore, screening of MDR Ab and carbapenemase for better treatment options is necessary.

Gap in measles vaccination coverage among children aged 9 months to 10 years in Ho Chi Minh City, Viet Nam, 2014

Introduction@#When Viet Nam launched the Expanded Programme on Immunization in 1981, it covered six vaccines, including measles. Subsequently, Viet Nam experienced a marked reduction in measles infections. A nationwide measles epidemic occurred in April 2014 and an investigation found that 86% of affected children aged 9 months to 10 years were not fully vaccinated; therefore, understanding the reasons for not vaccinating could improve vaccination coverage. @*Methods@#We performed a cross-sectional study to determine vaccination coverage and reasons for non-vaccination among children aged 9 months to 10 years in six districts in Ho Chi Minh City with the highest number of measles cases in 2014. Measles vaccination status of the youngest child in each household was determined and reasons for non-vaccination were investigated. A χ2 test and multiple logistic regression were used to identify independent predictors of full vaccination.@*Results@#In total, 207 children were enrolled during the study period in 2014. Full measles vaccination coverage was 55% in these households, and 73% of parents were aware of the importance of measles vaccination to protect their children. We found that the father’s education level (under high school versus high school and above) and the site where the survey was conducted were significantly associated with vaccination status.@*Conclusion@#The vaccination coverage was lower than the coverage reported by district preventive medicine centres of the seven study wards. Lack of the second vaccination was a key obstacle to eliminating the vaccination gap. A catch-up mass vaccination campaign or health promotion of measles vaccination directed towards parents should be considered to improve vaccination coverage.

Clinical testing of an inactivated influenza A/H5N1 vaccine candidate in a double-blinded, placebo-controlled, randomized trial in healthy adults in Vietnam.

We tested an inactivated egg-grown whole virus influenza A/H5N1 vaccine candidate developed by the Institute of Vaccines and Medical Biologicals (IVAC), a state-run vaccine manufacturer in Vietnam, in a Phase 1, placebo controlled, double blinded, randomized trial. The vaccine was adjuvanted with aluminum hydroxide. The trial enrolled 75 subjects who were randomized to receive two injections of one of the following: low-dose of vaccine (7.5 mcg HA), high-dose of vaccine (15 mcg HA), or placebo. The vaccine candidate was well tolerated with minimal local reactogenicity consisting of mild, short-lived injection site pain and/or tenderness. No systemic reactogenicity was observed other than transient low-grade fever in about 13% of the subjects and no unsolicited adverse events were attributable to product administration. Immune responses were assessed at baseline and after the first and second dose by hemagglutination inhibition (HAI) and microneutralization (MN) assays, with 72% of the high-dose and 68% of the low-dose vaccine recipients presenting a ⩾4-fold response in the HAI assay and 72% of the high-dose and 61% of the low-dose vaccine recipients exhibiting a ⩾4-fold response in the MN assay. These promising results support further development. ClinicalTrials.gov number NCT02171819, June 20, 2014.