Combined Polio Vaccines Were More Effective

Combining oral with injected vaccine reduced spread of virus and boosted immunity in children and infants

(RxWiki News) Since the development of vaccines in the 1950s, doctors and health care professionals have worked around the world to eradicate the spread of polio.

Although the disease is no longer a threat in the developed world, many people, particularly children, in poor and war-torn areas still face the condition.

New research suggests that using a combination of both available polio vaccines could boost immunity and reduce the spread of the disease.

"Consult a medical professional if you're traveling where polio is a concern."

The study was written by lead author Hamid Jafari, MD, director of polio operations and research for the World Health Organization (WHO), along with senior author Bruce Aylward, MD, assistant director general for WHO’s Polio, Emergencies and Country Collaboration, and colleagues.

Polio is an infectious disease caused by a virus that lives in the throat and intestines. It’s largely spread through water contaminated by feces.

Symptoms include fever, fatigue, nausea and body pain. In severe cases, polio can cause paralysis.

There are two vaccines for polio: inactivated poliovirus (IPV), which is injected, and live-attenuated oral poliovirus vaccine (OPV), which is swallowed.

Polio has largely been eradicated since the vaccines became available in the 1950s, but the virus still affects people in countries like India, Afghanistan, Pakistan and Nigeria.

The immunity that protects against polio quickly fades after OPV treatment. That means multiple doses are often necessary. Polio is still a problem in remote or conflicted areas, so giving more than one dose can be tough for medical workers.

The WHO research team, with an eye on cutting the need for multiple OPV doses, tested the effect of OPV and IPV on polio immunity.

They treated 954 Indian children and infants who were randomly assigned to receive either OPV or IPV. After four weeks, all of the participants received a dose of OPV.

Then, the study authors measured what’s called viral shedding, an indicator of how infectious a patient is to others.

In the group who received IPV, viral shedding was lower than the OPV group.

The authors also found that a single dose of IPV returned a higher level of immunity than an extra dose of OPV.

Dr. Aylward said in a press statement that the study “revolutionized our understanding of IPV and how to use it.”

“IPV should be used to accelerate the eradication of the virus in populations that have limited access to vaccination,” Dr. Jafari said in the press release.

Dr. Jafari added that the polio eradication effort is important for particular areas of the world.

"The global eradication effort is at a critical crossroad," he said. "[Polio] is increasingly geographically restricted to populations in insecure and inaccessible areas. Yet the virus in these areas persists with incredible tenacity and threatens the increasingly vulnerable populations in polio-free countries with weak or conflict-affected health systems."

The study was published online Aug. 21 in the peer-reviewed journal Science.

Rotary International’s PolioPlus program funded the study. The authors disclosed no conflicts of interest.

Review Date: 
August 20, 2014