Singapore to introduce mpox vaccination for healthcare workers and close contacts of confirmed cases

It has been recommended that close contacts be vaccinated within 14 days of exposure, while in quarantine, to reduce their risk of the disease.

Since the announcement by Singapore's Ministry of Health (MOH) of a health advisory against the mpox outbreak on 15 August, measures such as health screenings at Singapore's air & sea checkpoints have been implemented as of 23 August. 

As a refresher, mpox, caused by the monkeypox virus, has two subtypes: Clade I and Clade II. 

Clade II has been circulating globally as part of the 2022 multi-country outbreak, while Clade I cases have recently surged in the Dominican Republic of Congo and its neighbouring countries. 

Symptoms include a rash, fever, and fatigue, with an incubation period of six-21 days and spreads through close physical contact. 

In an update on 4 September 2024 (Wednesday), MOH detailed the measures that will be enforced, adding that it will monitor the situation closely and is prepared to respond should the situation worsen. 

Of those measures, a live attenuated (non-replicating) vaccine, JYNNEOS has been approved for Singapore to use to protect against mpox as well as smallpox. 

Per the announcement, the vaccine will be administered selectively to two groups: 

1. Healthcare workers who are at the highest risk of mpox exposure, particularly those in the National Centre for Infectious Diseases providing direct care to Clade I cases, will be offered JYNNEOS as pre-exposure prophylaxis. This is in addition to personal protective equipment and infection control protocols, ensuring extra protection for this vulnerable group.
2. The Expert Committee on Immunisation has recommended that a single dose of the JYNNEOS vaccine be offered and administered to close contacts of confirmed mpox cases within 14 days of exposure to reduce their risk of the disease. This will be administered while they are in quarantine.  

MOH has assured that the disease is less infectious as compared to COVID-19.

"Every person infected with mpox spreads the disease to an average of 1.3 other persons. Comparatively, without measures, each case of COVID-19 and its subsequent variants spreads to an average of two to five persons," the Ministry added. 

Other response measures that MOH has implemented are as follows: 

Border updates

Singapore has implemented temperature and visual screening at Changi and Seletar airports for arrivals from areas at risk of an mpox outbreak, as well as sea checkpoints for travellers from mpox-affected areas. 

Health advisories are in place at air checkpoints, urging travellers to take precautions, and travellers must report mpox-related symptoms and travel history via the SG Arrival Card, with those showing symptoms assessed by doctors at the borders and referred to hospitals if needed.

Detection, tracing, and isolation

MOH has instructed healthcare providers to promptly report all mpox cases, especially suspected Clade I infections. Suspected cases will be transferred to hospitals for further evaluation. 

If a Clade I case is confirmed, MOH will initiate contact tracing, with close contacts quarantined for 21 days in a designated facility.

Testing and treatment

Suspected Clade I mpox cases will be sent to designated hospitals for assessment and testing, with adults going to NCID, children to KK Women’s and Children’s Hospital, and family dyads to NUH. 

Cases will be isolated pending test results, with confirmed Clade I cases remaining isolated until non-infectious. 

Treatment will focus on supportive care, with severe cases receiving antivirals like Tecovirimat. 

MOH will continue to monitor new developments and assess the safety, efficacy, and suitability of emerging mpox therapeutics in meeting the needs of our population.

Other community measures

In terms of other community measures in place, MOH has advised that based on current evidence that mpox is spread mainly through close physical contact, such as within households, it does not recommend wearing a mask for people who are well.

"However, should there be evidence of significant respiratory transmission, such as outside of households and in public areas, MOH will consider implementing masking on public transport, and in crowded indoor places."

In preschools and schools (including special education schools), existing protocols for infectious diseases such as hand, foot and mouth disease remain in place. These include maintaining good hygiene and outbreak management measures such as isolation, contact tracing, temporary closure to contain the spread, and more.

In addition, wastewater testing is being conducted in migrant worker dormitories, with screening measures for new arrivals. 

Protocols for isolation, transport, and containment will also be put in place to manage potential mpox cases and prevent further spread.