Novavax Inc said data from a mid-stage study showed that immunizing pregnant women with its vaccine for a common respiratory virus was safe and could protect infants.
The news comes nearly half a century after a trial on another vaccine for the respiratory syncytial virus (RSV) resulted in the death of two toddlers. A vaccine is yet to be developed for the virus, which was discovered in humans in 1957, as it has a complex molecular structure.
Novavax said last month that a separate mid-stage study showed its vaccine protected the elderly against the virus.
RSV primarily affects those with compromised immune systems, including young infants and the elderly. For most older healthy children and adults, it causes little more than a common cold, but in high-risk groups it could lead to more serious lung infections, and sometimes, even death.
Novavax also said on Tuesday that it had received a grant of up to $89 million from the Bill & Melinda Gates Foundation to support a late-stage trial of the vaccine in pregnant women, which is planned for the first quarter of 2016.
A late-stage trial in the elderly is expected to begin later this year.
A RSV vaccine represents a $1 billion opportunity in the United States and double that number worldwide, Wedbush Securities analyst Heather Behanna said.
Novavax said the trial tested the vaccine against a placebo in 50 healthy pregnant women in their third trimester. Women who received the placebo showed no significant change in their antibody levels.
The data is consistent with immune responses observed in previous trials in women of child-bearing age, the company said.
Infants of the pregnant women who were given the vaccine were found to have received a significant bolus of all anti-RSV antibodies, Novavax said.
"Half of all hospitalizations due to RSV occur within first three months of birth and the vaccine demonstrates the potential to protect infants when they are most at risk," Gregory Glenn, Novavax's senior vice president of research and development, said in a statement.
The Maryland-based company's shares were down 2 percent at $7.99 in noon trading, reversing course.
(Reporting by Natalie Grover in Bengaluru; Editing by Shounak Dasgupta and Kirti Pandey)