IMPORTED CASE OF VACCINE-ASSOCIATED PARALYTIC POLIOMYELITIS INFECTION IN SINGAPORE

The Ministry of Health (MOH) has confirmed one imported case of vaccine-associated paralytic poliomyelitis in Singapore. The patient is a five-month-old female Indonesian infant who arrived in Singapore on 26 January 2025 for medical treatment.

2.               The case is immunocompromised and was previously vaccinated with one dose of oral polio vaccine (OPV) and one dose of inactivated polio vaccine (IPV) in Indonesia. She had developed fever, acute floppiness and paralysis of the lower limbs in December 2024 while in Indonesia. Poliomyelitis was not suspected by her doctor then. On 26 January 2025, she was medically evacuated for treatment of her symptoms and admitted directly to the National University Hospital (NUH) upon arrival in Singapore. The case is currently in stable condition.

3.               Our findings so far indicate low risk of community transmission. The case was conveyed directly to NUH upon arrival in Singapore and isolated upon admission. She was also placed under the appropriate infection prevention and control precautions to prevent further spread once suspected of poliomyelitis infection. Currently three close contacts, who are family members or caregivers of the case, have been quarantined as a precautionary measure.

4.               Poliomyelitis is caused by the poliovirus and mainly transmitted through food infected with faecal material. Vaccination is the most effective protection against poliomyelitis, alongside maintaining high standards of hygiene and sanitation. There are two vaccines for polio – OPV, which contains live attenuated (weakened) poliovirus, and IPV, which does not contain any live poliovirus. Many countries have progressively switched to IPV, and Singapore stopped using OPV in 2021.

5.               Vaccine-associated paralytic poliomyelitis is an extremely rare adverse event that occurs when an individual develops paralytic polio after receiving OPV. The risk is higher for immunocompromised persons, for whom IPV is recommended instead of OPV.  

6.               Singapore has not reported any locally acquired cases of polio since 1978. The last polio case reported in 2006 was an imported case. Singapore has maintained our polio-free status by continuing high polio vaccination coverage, high standards of environmental hygiene and sanitation, and having an established surveillance system in place to detect possible cases of poliomyelitis.

7.               Under the National Childhood Immunisation Schedule (NCIS), children receive a total of five vaccine doses – three IPV doses for infants at two months, four months, and six months, with another two booster doses of IPV at 18 months and 10 to 11 years old respectively. As the IPV does not contain live virus, it carries no risk of vaccine-associated paralytic poliomyelitis. Vaccinations in the NCIS are available free to all Singaporean children at Community Health Assist Scheme General Practitioner clinics and polyclinics.