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Professor of medicine Drew Weissman said that vaccines that require multiple doses are hard to implement in areas with poor infrastructure because it can be hard to ensure people get their follow-up vaccinations.

Credit: James Gathany

The Zika virus may be mostly out of the news after its summertime peak, but Penn Medicine is still actively working to combat the spread of the disease.

A new vaccine developed at Penn Medicine could provide long-term protection against the Zika virus with just a single, relatively low dose. The virus continues to affect 76 countries in Central and South America and the Caribbean, with isolated local transmission cases in Florida.

Unlike other vaccines currently being developed, this new immunization does not use live viruses, which tend to cause adverse side effects and are not effective for those who have already been affected by the virus.

The new vaccines uses tiny strands of RNA that hold the genetic codes for making viral proteins that block Zika infection.

Drew Weissman, professor of medicine at the Perelman School of Medicine and senior author of the report on the new vaccine, said vaccines that require multiple doses are difficult to implement in areas with poor infrastructure.

“The population that you would immunize right now is across South America, and much of that is very poor regions without much infrastructure for medical care, so if you had to give a vaccine twice or more, you would have to set up clinics and ways of following people to make sure everybody got immunized with two doses,” Weissman said.

“With a single dose, you go in, you find everybody, you immunize them once and you’re done,” he continued.

Up to this point, the vaccine has been tested on lab mice and monkeys. Human clinical trials are expected to start within 12 to 18 months.

“The most important finding of this paper is that the vaccine is safe,” Norbert Pardi, research associate and co-author of the report, said. “We didn’t see any side effects after vaccination in mice and monkeys.”

Pardi also noted that the vaccine is protective after a single immunization with a relatively small dose.

“This is very important … [that] there is long-term protection,” Pardi said. “Many times, the problem with vaccines is that we get some protection for a while but after months or years, you have to be vaccinated again.”

Weissman said this type of vaccine could be applied to other diseases, including influenza, HIV and malaria.

The research involves collaboration with lab researchers at Duke University and the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

“There’s a lot of potential to move [the vaccine] into a lot of different directions,” he said.