Estimating the Public Health Impact of MERS-CoV Vaccination in Thailand: A Simulation-Based Approach

Natthaprang Nittayasoot; Panithee Thammawijaya; Rapeepong Suphanchaimat

doi:10.59096/osir.v19i3.284055

Authors

Natthaprang Nittayasoot Field Epidemiology Training Program, Division of Epidemiology, Department of Disease Control, Ministry of Public Health, Thailand https://orcid.org/0000-0002-0807-9281
Panithee Thammawijaya Senior Expert Committee, Department of Disease Control, Ministry of Public Health, Thailand https://orcid.org/0000-0001-5737-1935
Rapeepong Suphanchaimat Field Epidemiology Training Program, Division of Epidemiology, Department of Disease Control, Ministry of Public Health, Thailand; International Health Policy Program Foundation, Thailand https://orcid.org/0000-0002-3664-9050

DOI:

https://doi.org/10.59096/osir.v19i3.284055

Keywords:

Middle East respiratory syndrome coronavirus, MERS-CoV, Hajj pilgrims, vaccine effectiveness, model, Thailand

Abstract

Objectives: Middle East Respiratory Syndrome coronavirus (MERS-CoV) remains a public health concern for Thailand, because of the risk of importation from Thai pilgrims attending the Hajj. With MERS-CoV vaccines under development, evidence on their potential impact is needed for vaccination planning. This study aimed to estimate the potential public health impact of MERS-CoV vaccination among Thai pilgrims attending the Hajj under different vaccine effectiveness (VE) and transmission scenarios.

Methods: A compartmental model simulated MERS-CoV transmission among Thai and non-Thai pilgrims attending the Hajj over 30 days. Vaccination was applied only to Thai pilgrims before travel. VE scenarios of 30%, 50%, 70%, and 90% were compared with no vaccination across basic reproduction number (R₀) values of 1, 2, 4, 6, and 8. Outcomes included infection burden and transmission dynamics, severe cases, deaths, and timing of case occurrence.

Results: Increasing VE reduced the projected number of infections, severe cases, and deaths across all transmission scenarios. Without vaccination, cumulative infections among Thai pilgrims increased from 0.35 cases at R₀=1 to 60.69 cases at R₀=8. At R₀=8, cumulative incident cases over the 30-day simulation period decreased from 60.69 without vaccination to 6.05 with 90% VE. During the 30-day simulation, the maximum observed daily incidence decreased from 10.15 to 1.01 cases, and the maximum observed prevalence decreased from 33.65 to 3.36 cases. Cumulative severe cases decreased from 15.43 to 1.54 and deaths from 5.66 to 0.57. Vaccination also delayed prevalent cases reaching ≥1 case—the threshold for prompt notification—from day 10 to day 23.

Public Health Recommendations: Under lower-transmission conditions, routine vaccination of all Thai pilgrims may not be necessary. However, if MERS-CoV transmission or outbreak activity increases in Saudi Arabia, targeted vaccination should be considered if a safe and effective vaccine becomes available. Further studies should evaluate cost-effectiveness and the combined effects of vaccination and non-pharmaceutical interventions.

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