Moderna says its RSV vaccine for older adults is 84% effective at preventing serious illness

Moderna's respiratory syncytial virus, or RSV, vaccine for older adults was about 84% effective at preventing serious illness, according to data from a late-stage trial published Tuesday.

Adult patients in the clinical trial appeared to tolerate the vaccine well and there were no safety concerns identified, the data showed.

The company said it will ask the U.S. Food and Drug Administration for approval in the first half of 2023.

Pharmaceutical companies Pfizer and GSK have also announced promising results for their respective RSV vaccines in older adults. The FDA is expected to decide whether or not to approve both vaccines in May 2023.

There is currently no approved RSV vaccine for any age group, but pharmaceutical companies -- including Moderna, Pfizer and GSK -- have seen promising results in late-stage trials.

Cases of RSV began appearing earlier than usual this year across the United States, according to the Centers for Disease Control and Prevention, peaking in early November before turning down.

Symptoms can include fever, coughing, runny nose, sneezing, wheezing and a decrease in appetite, per the CDC.

RSV leads to mild illness in most people but can cause severe illness in some young children and older adults.

The CDC says older adults aged 65 and above are at high risk for severe infection from RSV, particularly those with chronic lung or heart conditions and weakened immune systems.

Each year, between 60,000 and 120,000 older adults are hospitalized and between 6,000 to 10,000 die due to RSV infection, according to data from the CDC.

"Today's results represent an important step forward in preventing lower respiratory disease due to RSV in adults 60 years of age and older," Stéphane Bancel, Moderna's CEO, said in a statement. "These data are encouraging and represent the second demonstration of positive phase 3 trial results from our mRNA infectious disease vaccine platform after Spikevax, our COVID-19 vaccine."

Bancel said full results will be published at an upcoming infectious disease medical conference but did not specify which one.

This is not the first time researchers have attempted to develop an RSV vaccine.

In the late 1960s, a vaccine was produced in which the virus was inactivated with formalin, a chemical that kills viruses. The shot was given to children in Washington, D.C., but 80% of those immunized became sick and two children died, according to a journal article published in Nature.

Studies found that the vaccine did not generate enough antibodies to fight off the virus and instead triggered an overactive immune system response.