Researchers in Tokyo are developing a “dream” COVID-19 vaccine that offers lifetime efficacy, in what would be a game-changer as the fight against the coronavirus drags on into its third year.
At a time when it appears most COVID-19 vaccines will require periodic boosters due to a decline in recipients’ antibody levels, the creation of a vaccine with lifetime efficacy could lead to huge financial savings globally and give the world an upper hand against the coronavirus, which has infected more than 270 million people and claimed more than 5 million lives around the world.
Soon after the pandemic began, in early 2020, Michinori Kohara, emeritus investigator at the Tokyo Metropolitan Institute of Medical Science, wondered if it was possible to develop a vaccine based on the tried and tested smallpox vaccine — which helped the world eradicate the deadly disease. The vaccinia virus used in the smallpox vaccine is a subject he has worked on for over three decades, and Kohara knows firsthand how significant a vaccine that gives strong protection for life can be.
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The smallpox vaccine was developed by British doctor Edward Jenner in 1796 to counter the infectious disease, which had an extremely high mortality rate. In Japan, there has been no patients since 1956 and the government’s periodical vaccination ended in late 1970s. The vaccine remains the only shot that has successfully eradicated an infectious disease, with the last known case being a patient in Somalia in 1977 after a coordinated global vaccination campaign by the World Health Organization.
So in April 2020, Kohara, in cooperation with the National Institute of Infectious Diseases, started developing a recombinant vaccinia virus containing the spike protein of the SARS-CoV-2 virus, which causes COVID-19. They picked the nonpathogenic strain of the vaccinia virus variant called DIs, which works as an extremely effective and safe viral vector for delivering the SARS-CoV-2 spike gene.
While the messenger RNA COVID-19 vaccines developed by Pfizer Inc.-BioNTech SE and Moderna Inc. have been successful in preventing severe illness and death, neutralizing antibodies fall significantly over six months after vaccination, making boosters necessary — particularly against the omicron variant.
In contrast, the vaccine that Kohara is spearheading can produce potent neutralizing antibodies within a week of inoculation and induce the strongest cellular immunity of any vaccine, he says. That would be significant as none of the currently available COVID-19 vaccines appear to offer long-term protection.
Experiments on mice using the recombinant vaccinia virus encoding the highly pathogenic avian flu HA gene have shown high antibody levels that were maintained for more than 20 months, or nearly the average life span of a mouse, and all vaccinated mice infected with the avian flu 20 months post-vaccination survived. In contrast, the unvaccinated mice all died.
