RSV Vaccine Fails In Clinical Trial: Novavax Switches Focus To Vaccinating Pregnant Women As Stock Plummets

Alicia Bayer

Pharmaceutical company Novavax is scrambling to appease investors after they were forced to report that their highly-anticipated RSV vaccine had completely failed to protect against RSV in the third stage of clinical trials. Now the pharmaceutical company is moving forward with marketing the failed vaccine to expectant mothers.

Despite attempts to do damage control, Novavax stock took a nosedive immediately after the announcement last week that the vaccine provided absolutely no protection against RSV in its third stage clinical trials. The company lost $1.5 billion dollars in market value "almost instantaneously," CNBC reported.

The vaccine was intended to protect against respiratory syncytial virus, better known as RSV. The illness is not generally a problem for healthy individuals, but it can be serious for the elderly and for at-risk infants.

The Mayo Clinic says that RSV is a virus that causes infections of the lungs and respiratory tract. It is such a common illness that almost all children have contracted it by the age of two. For healthy individuals, the symptoms are similar to those of the common cold and no treatment is needed other than providing comfort.

Indeed, Novavax's CEO told Reuters last year that their RSV vaccine could become "the largest selling vaccine in the history of vaccines in terms of revenue."

Researchers have been attempting to develop a vaccine against RSV for decades, with little success. One promising vaccine in the 1960s had catastrophic results, leading to worse infections in babies who were exposed to RSV and resulting in the death of two infants.

"For a long time after that happened, there was no work on RSV vaccines," Ruth Karron, director of the Center for Immunization Research at Johns Hopkins University Bloomberg School of Public Health, told Chicago Tribune. "It was just completely set aside."

Novavax developers are now scrambling to find another way to develop the vaccine. The company is continuing to move forward with its trials of Novavax on pregnant women, hoping that they can salvage the vaccine and their company.

They also are concerned about omissions in Novavax's reporting regarding its pregnant subjects.

"Another dark cloud hanging over the phase 3 maternal immunization trial is Novavax's omission of infection measurements from the 50-patient phase 2 trial announcement. Granted, 50 patients split into two groups wouldn't provide statistically relevant infection data, but the company's decision to omit these outcome measurements defined in the trial's protocol is troubling."

Breastfeeding is one of the most important ways that babies can be protected from complications of RSV. One study published in British Medical Journal found that among 115 babies who had been hospitalized for RSV infection, only eight of them were breastfed.

It's important to note that new mothers automatically pass on some immunity against RSV infection to their babies, as they do with all illnesses that they have naturally contracted. Ask Dr. Sears explains that this immunity starts to wane after birth, wearing off by about two months. The baby's own immune system is generally strong enough to easily fight off most common illnesses by age six months to nine months. Breastfeeding helps prolong this immunity against RSV and other illnesses and protect the baby from illness during this window before the baby's immune system is strong enough to fight these illnesses on its own.

[Primary Image by Keith Srakocic/AP Images]