A vaccine has been approved for use in Singapore for protection against smallpox and mpox. Called Jynneos, this live attenuated (non-replicating) vaccine will be administered selectively to healthcare workers at the highest risk of exposure and close contacts of mpox cases, according to a Ministry of Health (MOH) press release on 4 September.
## Background
The Jynneos vaccine will be offered as a pre-exposure prophylaxis to healthcare workers, particularly those at the National Centre for Infectious Diseases (NCID) who are in close contact with mpox Clade I cases. Additionally, close contacts of mpox cases, including both Clade I and Clade II, will receive the vaccine within 14 days of exposure to reduce their risk of the disease. The MOH has assured that the current supply of Jynneos is sufficient based on the current vaccination strategy and will be adjusted as the situation evolves globally.
## Healthcare workers and close contacts of mpox cases
Healthcare workers at the highest risk, such as those at NCID, will receive the Jynneos vaccine to provide additional protection. Personal protective equipment and infection controls remain the primary prevention methods. Close contacts of mpox cases will also be vaccinated, with those exposed to Clade I cases being quarantined for 21 days in a designated government facility. The Expert Committee on Immunisation recommends a single dose of the vaccine within 14 days of exposure.
## Mpox not as transmissible as Covid-19, population-wide vaccination not recommended for now
MOH noted that mpox Clade I is less transmissible compared to respiratory diseases like influenza and Covid-19. Each mpox case spreads to an average of 1.3 persons, whereas Covid-19 spreads to two to five persons. Given the current understanding of mpox epidemiology and the effectiveness of contact tracing and quarantine, population-wide vaccination is not recommended. There is also no vaccination recommendation for travellers to mpox-affected countries. Smallpox vaccination, which was required in Singapore until early 1981, provides cross-protection against mpox, offering some immunity to those aged 45 and older.
## What are the symptoms of mpox and how does it spread?
Mpox symptoms include rash, fever, muscle aches, swollen lymph nodes, and fatigue. The incubation period ranges from six to 16 days, up to 21 days. Individuals are infectious from symptom onset until all scabs fall off. Mpox spreads through close contact with respiratory secretions, skin lesions, bodily fluids, and contaminated objects. In adults, it is primarily transmitted through close physical contact, including sexual contact. In children, it spreads through household contact, playtime, and exposure to wild game. The ministry is monitoring the risk to children closely.
## Declared a public health emergency by the World Health Organisation on 18 August
The World Health Organisation (WHO) declared mpox a “public health emergency” on 18 August after over 15,600 cases and 537 deaths were reported in the Democratic Republic of the Congo (DRC) this year. Mpox, caused by two subtypes of the monkeypox virus (MPXV), Clade I and II, has been more severe in Clade I cases. The disease was primarily reported in Central and West Africa before 2022, with most cases outside Africa linked to international travel or imported animals. As of 4 September, the outbreak remains largely confined to Africa, with two severe Clade I cases reported in Sweden and Thailand.
## What measures have been taken so far?
On 23 August, temperature and visual screening were implemented at Changi and Seletar airports for inbound travellers from mpox-exposed regions. Health advisories have been issued at air checkpoints, urging travellers to maintain high personal hygiene, avoid contact with infected individuals or animals, and refrain from high-risk activities like casual sex. Travellers with symptoms will be referred for medical assessment. Returning travellers from affected countries should seek immediate medical attention if they develop symptoms within 21 days and inform their doctor of their recent travel history. MOH emphasised the importance of personal responsibility and good hygiene to reduce mpox transmission.
## Future implications and ongoing monitoring
MOH will continue to monitor the global mpox situation and adjust vaccination strategies as needed. The ministry highlighted the importance of maintaining precautionary measures against both Clade I and Clade II mpox. The public is advised to stay informed and adhere to health advisories to mitigate the risk of mpox transmission.
