July 1 (UPI) -- An experimental COVID-19 vaccine under development by pharma giant Pfizer and U.S. firm BioNTech has proven effective at producing neutralizing antibodies, the companies announced Wednesday.
Pfizer and BioNTech said in a study that all 24 participants in an early-phase clinical trial who received lower dose levels of the vaccine candidate, BNT162b1, generated antibodies against the coronavirus that causes COVID-19.
Some of the antibodies were found to be "neutralizing," or sufficiently powerful to halt the virus, the research states.
The level of "neutropenia" necessary to provide immunity, however, is not yet known and must be determined in a larger safety and efficacy trial scheduled for July.
The BNT162 program is testing at least four experimental vaccines, each of which represents a unique combination of mRNA format and target antigen, the companies said.
"We are encouraged by the clinical data of BNT162b1, one of four mRNA constructs we are evaluating clinically, and for which we have positive, preliminary, topline findings," Kathrin Jansen, Pfizer head of vaccine research and development, said in a statement.
"We look forward to publishing our clinical data in a peer-reviewed journal as quickly as possible."
BioNTech CEO Ugur Sahin said the preliminary data is promising because the vaccine candidate activated antibody responses at least as robust as convalescent sera, which is the antibody collected from patients who have recovered from COVID-19.
The companies said last month they're preparing a large-scale rollout that will produce millions of vaccine doses this year, and hundreds of millions next year.
Other vaccine candidates have also shown early promise in fighting COVID-19, including those begin developed by Inovio Pharmaceuticals and Moderna. A potential vaccine in China was approved this week for immediate use by military personnel.