The Biomedical Advanced Research and Development Authority, a division of the US Department of Health and Human Services, informed Sanofi's vaccine unit that it had "decided to focus on a more limited set of goals and deliverables" based on its review of all Zika-related projects after a decline in new infections.
"BARDA has informed us they intend to continue to fund activities required to advance vaccine development to a point where development would be indefinitely paused but could be restarted if the epidemic re-emerges," Ashleigh Koss, a spokeswoman for Sanofi, wrote in an email.
Granted $43 million from BARDA last year, Sanofi announced a research contract in July 2016 with the Walter Reed Army Institute of Research to help study the human safety and effectiveness of an inactivated virus vaccine originally developed by the institute.
The institute's inactivated virus vaccine technology, data and biologic samples had been shared with Sanofi at that time with the hope that the company could produce an effective vaccine against the mosquito-borne disease, which can also be sexually transmitted and passed from mother to baby in utero.
"We are currently working with BARDA to identify which of the ongoing initiatives should continue ... as well as which initiatives should be terminated," Koss explained.
She added that there are approximately 32 Zika vaccines in early development around the world. She said that estimate is based on comments made by Dr. Anthony Fauci, head of the National Institutes of Health's National Institute of Allergy and Infectious Diseases.
Fauci said he is not sure and has never mentioned an exact number of Zika vaccine candidates "in play," but he said authors of a recent article
in the Journal of Virus Eradication say there are 38 candidates at various stages of development.
On February 1, 2016, the World Health Organization declared Zika, which can cause birth defects and other neurological deficits, a Public Health Emergency of International Concern
However, in November, the WHO stated that it was no longer an emergency of international concern and in March
stated that no countries, territories or global areas had reported new infections over the past month.
Zika remains a concern to pregnant women and those hoping to become pregnant because the consequences for babies of women who are infected while pregnant can be devastating. In the United States, one in 10 Zika-infected mothers had babies with related birth defects last year, according to the US Centers for Disease Control and Prevention.
Sanofi will be "completing, with partial BARDA support," an ongoing study intended to provide guidance on Zika epidemiology and diagnosis "that can be applicable to any vaccine subsequently developed," Koss wrote. The study, which is being conducted in Colombia, Honduras, Mexico and Puerto Rico, is seeking enrollment of 2,400 volunteers, the company said.
As Sanofi places its Zika vaccine on hold, others, including its research partner, forge forward.
The Walter Reed Army Institute of Research said studies of the are vaccine ongoing, with results under review at a scientific journal. Additionally, the US Army Medical Research and Materiel Command is evaluating soldiers' and families' risk of Zika infection, resource allocation and other matters, including possible new business partners, before deciding the most appropriate next steps in regard to development of the vaccine.
"Right now, there's no indication that Sanofi is anything other than just sort of an individual situation that doesn't necessarily impact other companies," Fauci said.
His institute is working on a number of vaccine candidates
based on several approaches.
"Nothing has changed with regard to our vaccine approach," Fauci said. "We have a number of candidates at various stages of development."
The vaccine candidate that is furthest along is the National Institute of Allergy and Infectious Diseases' DNA candidate, which is in phase 2A/2B trials -- safety and effectiveness studies in which testing is done on humans -- in Puerto Rico, Texas and South America.
Fauci said the institute has a strong collaboration with BARDA, which provides some funding, though "mostly, BARDA funds the companies that we work with," he said. "Currently, BARDA is not funding any aspect of our DNA trial."
Inovio Pharmaceuticals is also continuing separate efforts to develop a DNA-based vaccine candidate to protect against Zika, according to Jeff Richardson, a spokesman for the company.
This Pennsylvania-based company recently completed a public offering of common stock to support various projects, including publication in the final quarter of this year of its vaccine clinical study
"We are moving forward on a (clinical) trial in Puerto Rico," Richardson said. "It's not an efficiacy trial, but because of how we set it up -- with 80 people getting the vaccine and 80 not -- we feel we may get efficacy data from this trial." He added that the company is also seeking funders for ongoing research of the experimental Zika vaccine.