Since the late 1980s, the Global Polio Eradication Initiative(www.polioeradication.org) has reduced the number of reported wild poliovirus (WPV) cases worldwide by more than 99 percent. But during the past six months, 10 countries have reported active transmission of WPV, and four of those countries have been linked to exportation of the disease to other nations, according to the CDC.
In response to the burgeoning threat posed by the disease, the CDC posted a July 7 Morbidity and Mortality Weekly Report (MMWR) Early Release that included an update to the agency's policy on polio vaccination(www.cdc.gov) for international travelers. The update offers guidance for U.S. physicians providing care for patients who plan to travel to or reside in WPV-affected countries for more than four weeks.
Deemed "interim guidance," the CDC said the update is intended to help ensure compliance with World Health Organization (WHO) International Health Regulations(www.who.int) for countries designated as "polio-infected," with the end goal of reducing exportation of WPV from those countries.
- The CDC's July 11 Morbidity and Mortality Weekly Report includes an update to the agency's policy on polio vaccination for travelers abroad.
- The CDC recommends infants and children receive a full series of inactivated polio vaccine at ages 6-18 months and 2, 4 and 4-6 years.
- The CDC recommends that adults who are traveling to countries with wild poliovirus circulation in the past 12 months and who are unvaccinated, incompletely vaccinated or whose vaccination status is unknown receive a series of three doses.
On June 2, the CDC also issued a health advisory(emergency.cdc.gov) providing guidance to health care professionals regarding the new WHO polio vaccination requirements for travel to countries with active poliovirus transmission.
Scope of the Problem
Three countries have experienced uninterrupted circulation of WPV: Afghanistan, Nigeria and Pakistan. In addition, WPV has been documented as circulating in Cameroon, Ethiopia, Equatorial Guinea, Iraq, Israel, Somalia and Syria during the past 12 months.
The report emphasized the importance of physicians reminding their patients who are traveling to polio-affected countries to always carry documentation of a polio booster with them in their International Certificate of Vaccination or Prophylaxis(www.who.int) to avoid travel delays.
Travelers staying in a WPV-affected country for longer than four weeks may also be required to show proof of polio vaccination when departing the country. According to the WHO polio vaccination requirements, the polio vaccine must be received between four weeks and 12 months before the date of departure.
For example, as of June 12, Pakistan is requiring proof of polio vaccination to exit the country, and the remaining polio-exporting countries are expected to implement similar requirements, according to the MMWR report.
As for the most active and up-to-date go-to information on traveling to poliovirus-affected countries, AAFP member Doug Campos-Outcalt, M.D., M.P.A., of Phoenix, said he recommends the CDC's collection of resources(wwwnc.cdc.gov) over any others because of their accuracy and comprehensiveness.
CDC Recommendations for Infants and Children
The CDC recommends infants and children receive a full series of inactivated polio vaccine (IPV) at ages 6-18 months and 2, 4 and 4-6 years.
If the full series cannot be administered at the recommended intervals before traveling to WPV-affected countries, the remaining IPV doses should be administered using an accelerated schedule:
• The first dose should be given to infants older than 6 weeks.
• The second and third doses should be administered at or after four weeks following each previous dose.
• The minimum interval between the third and fourth doses is six months.
CDC Recommendations for Adults
The CDC recommends that adults who are traveling to countries with WPV circulation in the past 12 months and who are unvaccinated, incompletely vaccinated or whose vaccination status is unknown receive a series of three doses:
• Two doses of IPV should be administered at an interval of four to eight weeks, and
• A third dose should be administered six to 12 months following the second vaccination.
If three doses of IPV cannot be administered at the recommended intervals before travel, the following alternatives are recommended:
• If departure is more than eight weeks away, three doses of IPV should be administered at four weeks or more apart.
• If departure is less than eight weeks but more than four weeks away, two doses of IPV should be administered at four weeks or more apart.
• If departure is in less than four weeks, a single dose of IPV is recommended.
The CDC recommends that adults who completed a routine vaccination series of either IPV or oral polio vaccine during their childhood should still receive one dose of IPV before travel to affected countries.
A Vaccination Reminder
The resurgence of wild poliovirus and subsequent heightened focus on the disease should once again serve as a reminder to family physicians to discuss the importance of vaccination with their patients.
"This illustrates the ongoing need to insure that all of our patients receive a full set of recommended vaccines," said Campos-Outcalt.