Available Vaccines
Yellow Fever
Introduction
Yellow fever (YF) is an acute viral haemorrhagic disease caused by an arbovirus belonging to the Flavivirus genus in the Flaviviridae family. It is primarily transmitted through the bite of day-biting female mosquitoes, particularly Aedes species, Haemagogus species and Sabethes species. These mosquitoes breed in domestic, semi-domestic and forest environments.
Following an incubation period of 3-6 days, yellow fever presents with fever, headache, general body aches, vomiting and weakness, for 3-4 days. Around 15% present with severe infection that includes high fever, jaundice, vomiting, bleeding, organ failure and shock, resulting in death within 7-10 days for 50% of these patients.
YF is endemic in sub-Saharan Africa and the tropical regions of South America. However, it is not naturally found in Asia. Outbreaks are periodic in Africa and occur sporadically in South America. The presence of Aedes mosquitoes in Asia heightens the potential risk of YF transmission, making Malaysia at risk.
Table 26.1 Vaccines Registered in Malaysia
Table 26.2 High-Risk Groups in Malaysia
Implications for Healthcare Workers (HCWs)
The vaccine is not routinely recommended for HCWs in non-endemic settings.
Evidence for Effectiveness
In a meta-analysis reported in 2024, pooled seroprotection rates among healthy adults (mostly travellers) in a non-endemic setting were 94% (95% CI 86–99), whereas it was 76% (65–85) in an endemic setting.
These findings align with clinical evidence showing that protective immunity develops in 80–100% of people within 10 days, and in over 99% within 30 days. A single dose provides protection for at least 10 years, possibly lifelong, and therefore a booster is not recommended.
Yellow fever vaccine generally safe. However, a careful risk-benefit assessment for the adult >60-year-old, because they are higher risk of serious adverse effects related to Yellow Fever vaccine i.e:
- Yellow fever vaccine–associated viscerotropic disease (YEL-AVD): a very rare condition resembling severe yellow fever infection.
- Yellow fever vaccine–associated neurotropic disease (YEL-AND): rare neurological complications such as encephalitis or Guillain-Barré syndrome.
References
- World Health Organization. (October 20, 2025). Yellow fever: Fact sheet. https://www.who.int/news-room/fact-sheets/detail/yellow-fever
- World Health Organization. (November 19, 2022). Vaccination requirements and recommendations for international travellers, and malaria situation per country (2022 edition). https://www.who.int/publications/m/item/vaccination-requirements-and-recommendations-for-international-travellers-and-malaria-situation-per-country-2022-edition
- Centers for Disease Control and Prevention. (April 23, 2025). Yellow fever. In CDC Yellow Book 2026: Health information for international travel. https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/yellow-fever.html
- Schnyder, J. L., de Jong, H.K., Bache, B.E., Schaumburg, F., and Grobusch, M.P. (2024). Long-term immunity following yellow fever vaccination: A systematic review and meta-analysis. The Lancet Global Health, 12(3), e445–e456. https://doi.org/10.1016/S2214-109X(23)00556-9
- Ministry of Health Malaysia. (October 12, 2022). Yellow fever travel advisory. https://www.moh.gov.my/moh/resources/Info%20kesihatan/Yellow%20Fever/Yellow_Fever_Travel_Advisory_updated_12_October_2022.pdf
- Ministry of Health Malaysia. (January 17, 2025). List of approved private yellow fever vaccination centres in Malaysia https://www.moh.gov.my/moh/resources/Yellow%20Fever/List_of_approved_Yellow_Fever_Vaccination_Centres_in_Malaysia_updated_17_January_2025.pdf
- National Pharmaceutical Regulatory Agency (NPRA) Sistem Pendaftaran Produk & Perlesenan.https://quest3plus.bpfk.gov.my/pmo2/index.php