Two is better than one, at least in the case of polio.
Researchers have found that though the oral polio vaccine is effective, an additional injection of an inactivated form of the virus will boost immunity.
"The results of this study are truly historic in the context of global polio eradication," said Dr. Bruce Aylward, study author and the World Health Organization assistant director general for polio. "This study has revolutionized our understanding of inactivated polio vaccine and how to use it in the global eradication effort to ensure children receive the best and quickest protection possible from this disease."
The study found that though neither vaccination by itself provides the protection researchers wanted, together, the vaccines achieve the most optimal results.
The fight against polio has been regarded as one of global health's biggest success stories. In 26 years, the disease has dropped from 350,000 cases in more than 125 countries to just widespread in three countries and the cases have fallen by 99 percent.
The oral vaccine consists of a two-drop dose of a weakened polio virus. This form of the vaccination works through giving resistance to the disease to the digestive track. The injected vaccination, on the other hand, works in the bloodstream.
Trials in India have shown that the drops plus the injected vaccine is more effective than previous attempts at just giving children multiple oral doses of the vaccine.
Researchers found that children vaccinated with the oral form of the vaccine that were then given a boost from the injected vaccine had the lowest amount of virus in their feces, which is one of the key ways the virus is spread from person to person, compared to those who received the oral vaccine and then another boost of the oral vaccine.
Though the oral vaccine is cheaper and easier to give to children, the oral vaccine itself has not completely eradicated the virus that is still rampant in areas such as northern India.
It also turns out that the immunity children get from just the oral vaccine decreases over time.
The double-vaccine approach is currently used in Nigeria and will soon be introduced to Pakistan.
