Yellow fever

What is yellow fever?

Yellow fever is a mosquito-borne acute viral haemorrhagic disease which is caused by the yellow fever virus. Vaccination is a key preventive measure against yellow fever.

How is yellow fever transmitted?

Yellow fever is transmitted through the bite of an infected Aedes mosquito. Although there are no reported cases in Singapore, any importation of the disease could result in the disease taking root here due to the presence of the Aedes mosquito vector.

What are the symptoms of yellow fever?

Most infected persons are asymptomatic or have only mild illness. Symptoms of yellow fever include:

• Fever

• Headache

• Myalgia

• Nausea

• Vomiting

A more severe form of the disease is characterised by high fever, jaundice, bleeding, and eventually shock and failure of multiple organs.

What are the risk factors?

Travel to a yellow fever endemic country without yellow fever vaccination at least 10 days prior to start of travel.

How is yellow fever treated?

There is no specific treatment for yellow fever. Treatment is mainly supportive.

How to prevent yellow fever?

Yellow fever vaccination

 Vaccination is a key preventive measure against yellow fever. To protect against yellow fever during travel to countries at risk of yellow fever transmission, it is advised to receive yellow fever vaccination 10 days before travel. A single dose provides life-long protection against yellow fever.

Precautions against mosquito bites

Persons who are not eligible to receive the vaccination (e.g. children aged 1 year and below and persons with contraindications) are advised to take precautions. These include

• Staying in rooms which are well-screened or air-conditioned

• Wearing long, covered clothing that cover most of the body

• Applying an effective insect repellent, such as those containing DEET, Picaridin or IR3535 as the active ingredient regularly

Yellow fever vaccination requirements to enter Singapore

Singapore is free from yellow fever. To reduce the risk of importation and transmission of yellow fever in Singapore, all travellers, including Singapore residents, with travel history to countries with risk of yellow fever transmission (regardless of area, city or region) in the 6 days prior to arrival in Singapore are required to have a valid yellow fever vaccination certificate and present it to the Immigration and Checkpoints Authority (ICA) officer at the immigration counter upon arrival to Singapore. The certificate is also required for travellers with more than 12 hours airport transit in these countries.

The International Certificate of Vaccination for yellow fever becomes valid 10 days after vaccination* and the validity lasts for the life of the person vaccinated.

^{*For example, if the vaccine was administered on 1 January 2021, the vaccination certificate is considered valid from 11 January 2021 onwards.}

Travellers without a valid yellow fever vaccination certificate (e.g., unvaccinated persons, including those who are ineligible to receive the vaccination, and travellers whose certificate has yet to become valid), are liable to be quarantined under the Infectious Disease Act, for 6 days from date of departure from countries with risk of yellow fever transmission. The period of quarantine is to cover the incubation period for yellow fever (i.e., 6 days). For travellers whose vaccination certificate has yet to become valid upon arrival in Singapore, they will still be required to complete the quarantine even if the vaccination certificate subsequently becomes valid during quarantine. This is because they would not have been fully protected against yellow fever during their time in affected countries and may already be infected and incubating the infection. Quarantine must be served at a designated vector-free government quarantine facility. Non-residents who refuse quarantine will be denied entry into Singapore. 

Please refer to Health Advice for Travellers for the full list of precautions to take when travelling.