Polio cases are rare but continue to occur in countries where there are unvaccinated populations.
| A | Wild-type polio type 1 (WPV1) | Pakistan, Afghanistan, Nigeria |
| B | Vaccine polio type 1 (VDPV1) | Malaysia (Sabah), Indonesia, Myanmar, Papua New Guinea |
| C | Vaccine polio type 2 (VDPV2) | Philippines; Africa (Angola, Central African Rep, Dem Rep of Congo, Ethiopia, Ghana, Mozambique, Niger, Nigeria, Somalia) |
Poliomyelitis (usually called polio) is a viral infection transmitted by contaminated food and water. Most polio infections don't result in any symptoms, but when a person does have symptomatic disease, polio can result in acute flaccid paralysis, and life-long disability.
Polio has not yet been eradicated worldwide, so polio vaccine continues to be an essential childhood vaccine. However, vaccination rates have dropped in some countries.
There are 2 vaccines, oral polio vaccine (OPV) and injected polio vaccine (IPV). OPV is a live vaccine unlike IPV, but OPV continues to be useful because it is less expensive, and does not require injection. Both vaccines were trivalent, containing all 3 strains of polio virus, but after 1 May 2016, OPV was switched to bivalent, with type 2 polio virus removed. This was to reduce the risk of vaccine-derived polio, mainly from type 2 virus.
In countries that have inadequate polio vaccination rates, and are using OPV, live virus from OPV is excreted into sewage systems. The virus can circulate in the community, and revert on very rare occasions, causing polio infection in unvaccinated individuals.
Everyone travelling to countries with polio transmission should be up-to-date on their polio vaccinations.
Most adult Singaporeans who were born and grew up in Singapore since the 1960's would have had polio vaccinations as children, and are protected. Many NS men were given trivalent OPV at SAF enlistment.
Children < 18 years of age are protected if they have had ≥ 4 doses of polio vaccine.
Adults are protected if they already had an IPV booster at/after age 18.
Adults are protected if they already had an OPV booster at/after age 18, and it was given before May 2016.
Polio vaccine recommendations for adults will depend on destination, duration of travel, childhood polio vaccines taken, if they had a polio booster at/after age 18, and whether OPV was given after May 2016.
OPV from May 2016 onwards covers type 1 & type 3, but no longer includes type 2. IPV remains trivalent.
IPV is currently prioritized for those who need an adult booster because of travel > 4 weeks to the Philippines and certain African countries (Group C in table above) which have type 2 polio cases.
IPV is also needed for pregnant and immunocompromised travelers who cannot receive OPV safely.
We hope this information is helpful. If you have questions, please consult your doctor or nurse.