Several experimental Ebola vaccines are being fast-tracked into human clinical trials -- and at least one will be tested on U.S. volunteers -- as health agencies in this country and abroad gear up for full-blown combat.
The National Institute of Allergy and Infectious Diseases announced a new trial last week, its second since September; pharmaceutical giant Johnson & Johnson confirmed that it's at work on Ebola vaccines as are scientists in Denmark, Britain and Russia.
"Vaccines are considered silver bullets," said Dr. Aaron Glatt, chief executive of Mercy Medical Center in Rockville Centre.
"Historically vaccines have been extremely successful and the biggest example of that is the smallpox vaccine because it stopped one of the world's most infectious viruses," said Glatt, a specialist in infectious diseases.
A planned study by the allergy and infectious diseases institute will enroll 39 healthy volunteers between the ages of 18 and 65. They are to be divided into groups to receive either the experimental Ebola vaccine or a placebo. Early-round volunteers will probably be health care workers.
The institute, a division of the National Institutes of Health, is developing vaccines and medications to aid a growing Ebola defense.
The latest candidate vaccine is an experimental Canadian product called VSV-ZEBOV. Federal scientists plan to test it for safety and its capacity to generate an immune response. Researchers will examine the blood of volunteers who receive VSV-ZEBOV for evidence of Ebola antibodies.
Antibodies are minuscule Y-shaped proteins that neutralize pathogens. Volunteers will be given two intramuscular doses, a strategy known as a prime-boost.
Walter Reed Army Institute of Research is simultaneously testing VSV-ZEBOV as a single-dose vaccine at its clinical trials center in Maryland.
"The need for a vaccine to protect against Ebola infection is urgent," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
On Friday he explained there hadn't been much need for an Ebola vaccine in the past because before the epidemic, the infection had stricken fewer than 2,500 people in 40 years. The current outbreak accentuates the need for a vaccine, Fauci said.
VSV-ZEBOV contains a genetically engineered version of the vesicular stomatitis virus -- VSV -- which generally infects rodents, cattle and swine. VSV infections in humans are rare and don't cause disease, scientists said.
In the vaccine, the gene for the outer protein of the vesicular stomatitis virus has been replaced with a segment of a gene from the Zaire Ebola strain, which lies at the heart of the outbreak. The vaccine cannot cause an individual inoculated with it to develop Ebola because only a noninfectious segment of the gene has been used.
Dr. David Hirschwerk, an infectious diseases specialist at North Shore University Hospital in Manhasset, said candidate vaccines are not always the preventives scientists had sought. Some products, he said, simply don't work when tested in clinical trials.
"There are certain pathogens for which there are no vaccines," said Hirschwerk, referring to HIV, dengue and malaria.
Testing of another Ebola vaccine codeveloped by institute scientists and researchers at GlaxoSmithKline began last month. About a million doses can be ready by the end of 2015, GSK officials say.
Johnson & Johnson, meanwhile, plans a vaccine trial in West Africa starting in January. The effort will be conducted in collaboration with the World Health Organization and Bavarian Nordic, a pharmaceutical firm in Denmark.
Johnson & Johnson officials say the company is investing $200 million in Ebola vaccine development. Company scientists are working on a vaccine that targets only Ebola Zaire and another that targets multiple Ebola strains.