A new oral polio vaccine promises to help make polio a disease of the past, according to the results of a phase 1 clinical trial.
Polio was almost eliminated worldwide — except in vaccine-induced cases. In those cases, the weakened virus used in vaccines developed the ability to escape from immunized individuals and spread in places with low vaccination rates.
The new designer vaccine is the first in 50 years. Its developers used genetics to redesign the vaccine to make certain that it won't infect recipients.
Based on the early trial, the new vaccine appears not to cause humans to get the disease, according to the international team of researchers that is testing it.
"To my knowledge, this is the first effort to rationally design a live attenuated virus based on detailed understanding on its biology, as opposed to the standard approach of blindly passaging the virus in animal cells to eliminate human virulence through poorly understood mechanisms," said Raul Andino, a leader of the effort. He's a professor of microbiology and immunology at the University of California, San Francisco.
His team also included virologists from the Bill and Melinda Gates Foundation and the Center for Vaccine Innovation, both in Seattle; the University of Antwerp in Belgium; and the National Institute for Biological Standards and Control in the U.K.
For the study, they tried the vaccine on 15 adult volunteers at the University of Antwerp. All had had been vaccinated before.
Researchers found that the new vaccine was more stable and more effective than the Sabin oral vaccine from which it was made.
The new vaccine made lots of antibodies to the poliovirus — and even though the virus was present in their stool, it did not infect or cause paralysis in mice, researchers said. In contrast, 90% of mice given the Sabin vaccine developed paralysis.
A phase 2 trial of the new vaccine is underway and shows promise, Andino said. The World Health Organization plans a phase 3 trial.
For the moment, however, Andino's lab is using what they've learned from developing the polio vaccine to create a vaccine for the pandemic coronavirus.
The report was published April 23 in the journal Cell Host and Microbe.