Testing shows differences in efficacy of Zika vaccines after one year

December 15, 2017 by Bob Yirka, Medical Xpress report
Infographic about Zika virus. Credit: Carla Schaffer / AAAS

(Medical Xpress)—A large team of researchers with members from Harvard Medical School, Walter Reed Army Institute of Research, Bioqual Inc. and MIT has found that the efficacy of the three types of Zika vaccines currently undergoing clinical trials varied widely in monkeys after one year. In their paper published in Science Translational Medicine, the group describes testing all three vaccines in rhesus monkeys and what they found.

The Zika virus has been widely reported in the press in recent years due to a surge in infections in South America and, and the heartbreaking consequences—babies with birth defects born to infected mothers. Fortunately, progress has been made in developing a vaccine to protect humans from the virus. To date, there are three leading candidates. One is based on injections of purified/inactive Zika virus samples; another is adenovirus vector-based, which means it is carried by one of the family of viruses that cause the common cold—and the third is DNA-based.

The three vaccines are currently at different stages of testing, though it is hoped that at least one of them will be available for commercial use very soon. One aspect of Zika vaccination that is not known, the researchers note, is how well they work after a length of time has passed. To find this answer for themselves, the researchers tested all three in monkeys over the course of a whole year.

The team reports that the DNA vaccine was no longer effective after a year had passed, suggesting it likely will not be the vaccine selected for use in humans—the inactive viral sample vaccines were better at approximately 75 percent effectiveness, but it was the adenovirus-based vaccine that showed the best performance offering 100 percent immunity against the a year after being given a single injection.

The researchers acknowledge that it is not clear if the three vaccines would offer the same results in humans, but note that testing in humans is going to be more difficult, because transmission rates are currently low, making it difficult to find patients to include in the trials. They suggest that studies such as theirs should offer some assistance in the path towards approval of the eventual .

Explore further: Trials show inactivated Zika virus vaccine is safe and immunogenic

More information: Peter Abbink et al. Durability and correlates of vaccine protection against Zika virus in rhesus monkeys, Science Translational Medicine (2017). DOI: 10.1126/scitranslmed.aao4163

Abstract
An effective Zika virus (ZIKV) vaccine will require long-term durable protection. Several ZIKV vaccine candidates have demonstrated protective efficacy in nonhuman primates, but these studies have typically involved ZIKV challenge shortly after vaccination at peak immunity. We show that a single immunization with an adenovirus vector–based vaccine, as well as two immunizations with a purified inactivated virus vaccine, afforded robust protection against ZIKV challenge in rhesus monkeys at 1 year after vaccination. In contrast, two immunizations with an optimized DNA vaccine, which provided complete protection at peak immunity, resulted in reduced protective efficacy at 1 year that was associated with declining neutralizing antibody titers to subprotective levels. These data define a microneutralization log titer of 2.0 to 2.1 as the threshold required for durable protection against ZIKV challenge in this model. Moreover, our findings demonstrate that protection against ZIKV challenge in rhesus monkeys is possible for at least 1 year with a single-shot vaccine.

Related Stories

Trials show inactivated Zika virus vaccine is safe and immunogenic

December 5, 2017
The investigational Zika purified inactivated virus (ZPIV) vaccine was well-tolerated and induced an immune response in participants, according to initial results from three Phase 1 clinical trials. Scientists at the Walter ...

DNA-based vaccine guards against Zika in monkey study

September 22, 2016
An experimental DNA-based vaccine protected monkeys from infection with the birth defects-causing Zika virus, and it has proceeded to human safety trials, researchers report.

Zika vaccine protects fetus against infection and birth defects

July 13, 2017
Immunizing female mice with a Zika vaccine can protect their developing fetus from infection and birth defects during pregnancy, according to new research from The University of Texas Medical Branch at Galveston. The findings ...

Research teams hone in on Zika vaccines, but challenges remain

February 21, 2017
As public health officials warn that spring's warmer temperatures may herald another increase of Zika virus infections in the Caribbean and North and South America, researchers around the world are racing to develop safe ...

France's Sanofi to work with US Army on Zika vaccine

July 6, 2016
French pharmaceuticals group Sanofi said Wednesday it would work with the US Army's Walter Reed Institute to develop a potential vaccine against the mosquito-borne Zika virus, linked to brain damage in newborns.

DNA-based Zika vaccine is safe and effective at inducing immune response

October 4, 2017
A new generation DNA-based Zika vaccine demonstrated both safety and ability to elicit an immune response against Zika in humans in a phase 1 clinical trial conducted through a partnership among the Perelman School of Medicine ...

Recommended for you

Lung-on-a-chip simulates pulmonary fibrosis

May 25, 2018
Developing new medicines to treat pulmonary fibrosis, one of the most common and serious forms of lung disease, is not easy.

Reconstructing Zika's spread

May 24, 2018
The urgent threat from Zika virus, which dominated news headlines in the spring and summer of 2016, has passed for now. But research into how Zika and other mosquito-borne infections spread and cause epidemics is still very ...

Tick bite protection: New CDC study adds to the promise of permethrin-treated clothing

May 24, 2018
The case for permethrin-treated clothing to prevent tick bites keeps getting stronger.

Molecular network boosts drug resistance and virulence in hospital-acquired bacterium

May 24, 2018
In response to antibiotics, a gene regulation network found in the bacterium Acinetobacter baumannii acts to boost both virulence and antibiotic resistance. Edward Geisinger of Tufts University School of Medicine and colleagues ...

Past use of disinfectants and PPE for Ebola could inform future outbreaks

May 24, 2018
Data from the 2014 Ebola virus outbreak at two Sierra Leone facilities reveal daily usage rates for disinfectant and personal protective equipment, informing future outbreaks, according to a study published May 24, 2018 in ...

Early lactate measurements appear to improve results for septic patients

May 24, 2018
On October 1, 2015, the United States Centers for Medicare and Medicaid Services (CMS) issued a bundle of recommendations defining optimal treatment of patients suffering from sepsis, a life-threatening response to infection ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.