Pfizer Doubles Down on Respiratory Viruses with RSV and COVID Pill Trials

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Pfizer Doubles Down on Respiratory Viruses with RSV and COVID Pill Trials


While COVID-19 continues to cut a deadly swath across the country, there are other respiratory illnesses raising their heads, including respiratory syncytial virus (RSV), the most common cause of viral pneumonia in young children and older adults.

This morning, Pfizer announced it dosed its first patients in a Phase III trial assessing a single dose of its investigational RSV bivalent prefusion F subunit vaccine candidate (RSVpreF) in adults ages 60 and above. According to Pfizer, the clinical trial is expected to include 30,000 adults and will assess safety and efficacy for the prevention of moderate to severe lower respiratory tract illness (msLRTI-RSV) during the first RSV season.

Kathrin U. Jansen, Ph.D., senior vice president and head of Vaccine Research and Development at Pfizer, said RSV is a challenging issue for many older Americans that can lead to disability or death. Jansen said there is an unmet medical need for an effective vaccine that can protect older adults against the contagious virus. 

“The start of this Phase III study is an important step forward towards our goal of comprehensive immunization against RSV disease, which includes developing a potential first vaccine to help prevent RSV disease in adults as well as the ongoing efforts to help protect infants through maternal immunization, subject to regulatory approval of the candidate vaccine,” Jansen said in a statement.

In addition to patients over the age of 60, Pfizer has also been studying RSVpreF in pregnant women. Last year, the company posted positive Phase IIb data regarding the safety, tolerability and immunogenicity of RSVpreF in vaccinated pregnant women ages 18 through 49. The U.S. Food and Drug Administration (FDA) granted Fast Track status to RSVpreF for this indication in 2018.

Pfizer’s COVID-19 vaccine was the first to reach full FDA approval, but the company is also working on an oral therapeutic for the pandemic. On Wednesday, Pfizer announced it has initiated a Phase II/III clinical study of 1,140 participants. If successful, the oral pill is expected to be used in a broad population of COVID patients.

PF-07321332 is an investigational orally administered protease inhibitor antiviral therapy that has been specifically designed to combat COVID-19 in non-hospitalized, symptomatic adult participants who have a confirmed diagnosis of COVID-19 infection. Pfizer noted the medication is for these patients who are not considered at increased risk of progressing to severe illness that could lead to hospitalization or death.

“Protease inhibitors, like PF-07321332, are designed to block the activity of the main protease enzyme that the coronavirus needs to replicate,” the company said.

A separate trial assessing PF-07321332 in patients who are at severe risk of illness began in July.


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