MONDAY, Feb. 13, 2023 (HealthDay News) -- The COVID-19 antiviral treatment Paxlovid continues to work against Omicron subvariants BA.4 and BA.5, new research shows.

Researchers decided to study Paxlovid’s impact against severe illness and death because doctors have fewer treatment options for high-risk patients as the virus evolves.

“We are really struggling with maintaining effective therapeutic options for high-risk patients with COVID-19,” said Dr. Adit Ginde, a professor of emergency medicine at the University of Colorado School of Medicine in Aurora, Colo.

“Particularly because the monoclonal antibody treatments we had been using and relying on for the past year-and-a-half are no longer effective against recent Omicron subvariants because the virus has changed,” Ginde explained in a university news release.

Currently the only antiviral treatment options still considered effective are Paxlovid and remdesivir.

According to lead study author Dr. Neil Aggarwal, an associate professor of medicine at the University of Colorado, “This study was one of the first to strongly suggest a benefit for the antiviral medication, nirmatrelvir-ritonavir, also known as Paxlovid, to prevent hospitalization and death for patients infected with recent Omicron SARS-CoV-2 variants.”

To come to that conclusion, the team examined the data of patients in the UCHealth system who had one or more risk factors for severe disease, hospitalization or death. Some had received Paxlovid, while some had not. The study included 28,000 patients.

The researchers found that Paxlovid significantly reduced rates of hospitalization and death. It was effective in preventing hospitalization among almost all the important subgroups of outpatients who qualify for its use, including those who are vaccinated.

“As a physician who can treat patients in the outpatient setting, I would be very comfortable using Paxlovid as a first-line treatment for adults acutely infected with COVID during the current Omicron phase, vaccinated or not, provided there are no contraindications to its use,” Aggarwal said.

The investigators also found that Paxlovid was associated with a lower rate of post-treatment emergency department visits, which suggests a lower likelihood of rebound symptoms.

“We provide clinicians with nearly real-time data to help support decision-making with robust systematic data,” Ginde explained. “If we can confirm benefits of a therapy, clinicians can be confident in prescribing a treatment, and patients can feel comfortable receiving treatment. If we find agents are losing effectiveness, we need to know that as well and change the treatments offered to patients.”

Real-world data platforms require multiple collaborations and time to build, the study authors noted.

“It takes a while to build this capability. But once you have the infrastructure, you can use it for COVID and other conditions,” Ginde said. “The [U.S. Food and Drug Administration] has also put out guidance to be able to use real-world evidence for regulatory decision-making.”

The research team plans to publish other real-world study results on the effectiveness of remdesivir against Omicron subvariants and an update on Paxlovid effectiveness for more recent Omicron subvariants, including XBB.1.5 and BQ.1.

“The laboratory data suggest that Paxlovid is still effective at neutralizing the virus in recent Omicron subvariants. However, we plan to evaluate ongoing clinical effectiveness in patients through our upcoming analyses,” Ginde said.

The findings were published Feb. 10 in the journal Lancet Infectious Diseases.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

SOURCE: University of Colorado Anschutz Medical Campus, news release, Feb. 10, 2023