Modelling the potential public health impact of different vaccination strategies with an omicron-adapted bivalent vaccine in Thailand.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19 has continuously evolved, requiring the development of adapted vaccines. This study estimated the impact of the introduction and increased coverage of an Omicron-adapted bivalent booster vaccine in Thailand. RESEARCH DESIGN AND METHODS: The outcomes of booster vaccination with an Omicron-adapted bivalent vaccine versus no booster vaccination were estimated using a combined cohort Markov decision tree model. The population was stratified into high- and standard-risk subpopulations. Using age-specific inputs informed by published sources, the model estimated health (case numbers, hospitalizations, and deaths) and economic (medical costs and productivity losses) outcomes in different age and risk subpopulations. RESULTS: Booster vaccination in only the elderly and high-risk subpopulation was estimated to avert 97,596 cases 36,578 hospitalizations, 903 deaths, THB 3,119 million in direct medical costs, and THB 10,589 million in indirect medical costs. These benefits increased as vaccination was expanded to other subpopulations. Increasing the booster vaccination coverage to 75% of the standard-risk population averted more deaths (95%), hospitalizations (512%), infections (782%), direct costs (550%), and indirect costs (687%) compared to the base case. CONCLUSIONS: Broader vaccination with an Omicron-adapted bivalent booster vaccine could have significant public health and economic benefits in Thailand.

Temporal Trend of COVID-19 Vaccine Acceptance and Factors Influencing International Travellers.

The COVID-19 pandemic has seen disrupted international travel due to travel restrictions and public health measures aimed at containing the spread of the virus. With increasing evidence of the COVID-19 vaccines' ability to mitigate disease severity, reopening tourism is desirable to promote the recovery of the global economy. However, the COVID-19 vaccine and vaccination passport for international travellers remains an ongoing debate. Little is known of the acceptance of these and the influencing factors among this population group. Therefore, this study sought to determine the temporal trend in COVID-19 vaccine acceptance and influencing factors among international travellers. A cross-sectional study was conducted using a self-administered questionnaire among international travellers who visited the Thai Travel Clinic, Hospital for Tropical Diseases, Mahidol University, Thailand from June 2021 to December 2021 (3 different variants dominated during this period). Study data were analyzed using SPSS software, version 23. Chi-square was used to demonstrate associations. Binary logistic regression was used to evaluate the magnitude of effect, demonstrated by odds ratio with 95% confidence interval. All significant variables were included in a multinomial logistic regression model to estimate adjusted odds ratios. The study enrolled 1068 travellers, 719 (67.3%) Thai and 349 (32.7%) foreign travellers. Most travellers were female (55.4%) and aged 18-30 years. The three main purposes for visiting the clinic were: for study, visiting friends and relatives, and returning to their home country. The overall COVID-19 vaccine acceptance rate among the travellers was 96.2%. The temporal trend of acceptance among Thai and non-Thai travelers varied from 93-99% and 93-100%, respectively. Vaccine efficacy, protective duration of the vaccine, risk of infection, and travel plan were factors strongly associated with COVID-19 vaccine acceptance. In conclusion, the COVID-19 vaccine acceptance rate among these international travellers was very high. The safe and effective reopening of tourism to international travellers will facilitate economic recovery.

The impact of COVID-19 pandemic on rabies post-exposure prophylaxis services in Asia.

Human rabies is a preventable disease through post-exposure prophylaxis (PEP) in rabies endemic countries where enzootic cycle of dog rabies occurs. The COVID­19 pandemic has induced an unprecedented challenge for under-funded and already stretched health­care systems particularly in low- and middle-income countries, which are unfortunately bearing a huge burden of human rabies. An analysis of hospital-based PEP data in India, Nepal, Sri Lanka, and Thailand, focus group discussion and key informant interview have been carried out to better understand the impact of Covid-19 pandemic in human rabies prophylaxis. It is necessary to better prepare for human rabies prophylaxis in future pandemics based on lesson learnt from current pandemic. The PEP should be categorized as an emergency medical service, and it should be part of the hospital medical emergency. Mass dog vaccination against rabies should be accelerated to reduce the risk of potential bite of roaming dogs and pet dogs in communities. It is a wise decision to invest in cost-effective preparedness, i.e., mass dog vaccination rather than costly response, i.e., human rabies prophylaxis.

Immunogenicity of 2-dose pre-exposure rabies vaccine co-administered with quadrivalent influenza vaccine in children.

OBJECTIVES: The World Health Organization recommends a 2-dose rabies pre-exposure prophylaxis (PrEP) regimen. This study aimed to compare the immunogenicity of rabies PrEP regimens co-administered with inactivated quadrivalent influenza vaccine (IIV4). METHODS: Children aged 3 to 9 years were randomly assigned (2:2:1) to receive 0.25 mL of chromatographically purified Vero cell rabies vaccine intramuscularly: Group A at day 0, 7 with IIV4; Group B at day 0, 28 with IIV4; Group C at day 0, 7. A booster-dose of CPRV was given on day 365. Primary outcome was the proportion of children with protective rabies virus neutralizing antibody (RVNA) ≥ 0.5 IU/mL, on day 42 and 7 days post-booster. RESULTS: From November 2019 to January 2020; 100 children with a median age (IQR) of 5.4 years (4.8-7.3) were enrolled. All participants achieved protective RVNA titers on day 42 and 7-days post booster. Geometric mean titers (GMT) at day 42 were Group A, 8.98(95%CI 7.06-11.42); Group B, 23.89(95%CI 19.33-29.51); Group C, 9.94(95%CI 7.03-14.06). Likewise, RVNA GMT at 7 days post-booster were Group A, 42.53(95%CI 18.41-66.64); Group B, 23.19(95%CI 17.28-29.10); Group C, 57.75 (95%CI 35.86-79.67). CONCLUSIONS: The 2-dose PrEP regimen of rabies vaccine produces adequate immune response either 0,7 or 0, 28 regimens.

Incidence of health problems in travelers to Southeast Asia: a prospective cohort study.

BACKGROUND: There are few studies of the incidence of health problems among travelers to Southeast Asia. The current study sought to determine the incidence of self-reported health problems among travelers visiting the region. METHODS: A prospective questionnaire-based study was conducted among travelers from high-income countries who visited Southeast Asia. Participants were enrolled at time of their pre-travel visit at Mahidol University, Bangkok, Thailand. Travelers were prospectively followed by self-administered questionnaires 2 weeks after arrival, upon return to their home country and 2 weeks after return. RESULTS: During January 2018-February 2019, 359 travelers were enrolled in Bangkok, Thailand, and the first questionnaire was administered. Follow-up questionnaires were returned by 191, 96 and 64 participants 2 weeks later, at the end of the trip and 2 weeks after return, respectively. A total of 6094 travel days were included in the final analysis. The incidence of acute diarrhea per month per 1000 travelers was 217 [95% confidence interval (CI), 189-248] episodes; skin problems, 197 (95% CI, 170-227); respiratory symptoms, 133 (95% CI, 111-158); fever, 49 (95% CI, 36-65); and potential rabies exposure, 34 (95% CI, 24-48). The incidence of acute diarrhea episodes per month per 1000 travelers was significantly higher during the first 2 weeks of travel compared with subsequent weeks of travel: 325 (95% CI, 291-362) vs 132 (95% CI, 110-1157) (P < 0.05). The incidence of outpatient visits and hospitalizations per month per 1000 travelers was 49 (95% CI, 36-65) and 5 (95% CI, 2-10), respectively. CONCLUSIONS: In this prospective cohort study we observed substantial burden of acute diarrhea and skin and respiratory symptoms among travelers to Southeast Asia. The higher incidence of diarrhea in the first 2 weeks of travel should be further investigated.