Are Two Polio Vaccines Better Than One? Research Says Yes

After hotly contesting the efficacy of two types of polio vaccine, researchers have reached the conclusion that a combination of both types is the best solution to stopping the spread of Polio.

Renewed concern follows a fresh outbreak of the virus in Pakistan, Cameroon, Guinea, and Syria last spring.  The WHO, in an emergency committee meeting, declared the need for a coordinated international response and singled out adult travelers as the primary contributor to the spread.

The Inactivated Polio Vaccine (IPV) and the Oral Polio Vaccine (OPV) were both discovered in the mid-twentieth centuries and each has its advantages and disadvantages. IPV is the vaccine most commonly used within the U.S. since 2000, and OPV is the most commonly distributed internationally.

Up until recently, the WHO has relied on OPV because the cost is low, it’s easy to administer to children, and it is more effective in stopping the spread of disease through feces.

IPV is not as effective in areas where sanitation poses a problem. Furthermore, the injectable is not only more expensive to manufacture, but more expensive to administer because it requires a trained health worker and a sterile needle for each use.  Finally, IPV does not stop the transmission of the virus.

Because of these disadvantages, the WHO used OPV in outbreaks when the disease needed to be contained.

Time reports that controversy over the two possible preventions erupted when the use of OPV in Northern India was not reducing the spread of the disease. Ordinarily OPV is administered in three separate doses, but it took an additional 10 to 12 vaccinations until the rate of infection finally went down.  Scientists discovered that the immunity offered by OPV wears off over time. 

Researchers in the region found that adding IPV to the treatment of children already vaccinated with OPV was more effective than continuing with OPV alone.

This research was corroborated by a report in Science released this week. Hamid Jafari, director of polio operations and research at WHO, told Time that the results of these studies “revolutionize our thinking about how to use polio vaccines properly.”