The choice of a vaccine for polio remains a question for debate for many scientists. However, a new study suggests that combining two polio vaccines may increase the immunity of the poliovirus in an individual.

Polio is an infectious disease that can spread through contaminated faeces and can cause paralysis or even death of the affected person. Government agencies throughout the world have worked hard to eradicate the disease and cases have dropped by around 99 percent. However, polio is still widespread in many countries such as Pakistan, Afghanistan, Nigeria and more.

One of the following two polio vaccines - inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV) - is usually administered to combat the deadly disease. However, a recent study suggests that giving a combination of these two vaccines may increase the possibility of crippling polio worldwide.

Many scientists prefer OPV as it is considered more effective and requires no needles. OPV is available in small vials and very easy to administer and people are usually given only two drops of the vaccine. However, some scientists have debated about OPV use as it can still cause poliovirus to be shed in faeces, which can lead to the risk of the virus spreading.

On the other hand, IPV is administered by an injection and some scientists believe that IPV is more effective in children than an extra OPV dose.

The researchers explain that they gave IPV to 1,000 children in India, who had already taken OPV. The scientists found that after receiving IPV these children increased their immunity to the poliovirus.

"The global eradication effort is at a critical crossroad," says Dr. Hamid Jafari, World Health Organization's (WHO) director for polio operations and research and the lead author of the report. "Endemic 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."

Dr. Bruce Aylward, assistant director-general for Polio, Emergencies and Country Collaboration at WHO and a senior author of the study, says that the findings of the new research may revolutionize the understanding of IPV. Dr. Aylward reveals that the study sheds light on how to use IPV globally to eradicate polio swiftly than previously thought.

The research has been published in the online journal Science.