Polio – Are you at Risk?
Many travellers are surprised when they learn they should receive a polio vaccine for their trip, believing polio to be a disease of the past. While it is true that Canada and the rest of the Americas was declared “polio-free” in 1994, polio remains a risk in certain countries. There may even be countries where proof of polio vaccination is required for travel.
What is polio?
Poliomyelitis, or polio, is spread by 3 types of polio viruses found in food and water contaminated by the feces of an infected person. It is a highly infectious disease that can invade the nervous system and cause paralysis and difficulty breathing. Symptoms of polio can range from asymptomatic to severe symptoms including acute flaccid paralysis, respiratory failure, and rarely death.
Polio vaccines in Canada
There are two types of polio vaccines, the Inactivated Polio Vaccine (IPV) and the live, oral polio vaccine (OPV). The polio vaccine was introduced into BC’s routine vaccine schedule in 1957 for children and adults. Over the years a combination of OPV and IPV have been used. The OPV was discontinued in Canada in 1994. Today, infants receive IPV in combination with other routine vaccines at 2, 4, 6, and 18 months of age, with a fifth dose between 4-6 years of age. An adult booster of polio vaccine is only recommended for health care workers who may be exposed to feces, or for travel to certain countries.
The goal for polio eradication
Prior to the introduction of the polio vaccine, wild poliovirus (WPV) was common worldwide. The Global Polio Eradication Initiative was initiated in 1988 and has succeeded in significantly decreasing the number of countries where WPV is a risk. WPV now remains a risk in only three countries: Afghanistan, Nigeria, and Pakistan.
The return of polio in polio-free countries
A decrease in immunization rates is to blame for the return of polio. Countries with extremely low immunization rates have seen cases of circulating vaccine derived polioviruses (cVDPV). Many countries worldwide vaccinate with OPV, which is a live, weakened vaccine that replicates in the intestines to produce antibodies and is then excreted in the feces. If a population is extremely under-immunized the excreted vaccine virus can continue to circulate for extended periods of time, which allows time for the virus to undergo genetic changes into a form that can cause disease. The excreted vaccine virus would need to be allowed circulation for at least 12 months for cVDPV to occur, which would only be possible among populations with extremely low immunization rates.
The Philippines, which had been polio free for 19 years, has experienced a decrease in immunization rates to 66% and as a result has recently seen 2 cases of cVDPV. Environmental samples from areas near the 2 cases tested positive for polio, indicating that polioviruses are likely circulating throughout the country.
The risk of cVDPV occurring is extremely low, and the benefits of using OPV far outweigh the risks. Since 2000 more than 10 billion doses of OPV have been administered worldwide to nearly 3 billion children, resulting in 13 million cases of polio being prevented and reducing the disease by 99%.
Risk to travellers
Before travelling to areas where there is wild poliovirus or vaccine-derived poliovirus travellers should ensure they have completed their primary polio vaccine series, which should typically have been completed as a child. Unvaccinated adults beginning the primary series should have 3 doses of the polio vaccine at 0, 1, and 6 months. Adults who have completed the primary series should receive an additional booster dose, which then provides lifetime protection against polio.
Polio vaccination requirements
Proof ofrecent polio vaccination may be required when travelling to polio-affected countries. In 2014 the World Health Organization (WHO) declared the international spread of polio to be apublic health emergency and issued temporary polio vaccine recommendations for travellers. Long-term travellers (staying >4 weeks) and residents may be required to show proof of polio vaccination when departing from polio-affected countries. The polio vaccine should be given between 4 weeks and 12 months before departure from the polio-affected country and documented on an International Certificate of Vaccine or Prophylaxis.
For more information about polio vaccine requirements visit the Center for Disease Control’s website: https://wwwnc.cdc.gov/travel/news-announcements/polio-guidance-new-requirements
Visit a travel clinic!
Country requirements for proof of polio vaccination are often changing. The experts at TravelSafe Clinic are up to date on polio outbreaks, current recommendations and requirements for polio vaccination. Book your consultation at TravelSafe Clinic to determine if you need the polio vaccine for your trip, and to receive your International Certificate of Vaccine or Prophylaxis.
TravelSafe Clinical Educator – Kristin Cain, RN, BSc, MSc(A)