Two years after baloxavir marboxil was approved by the FDA as a treatment for patients with the flu, a new study in the New England Journal of Medicine showed the drug can also help prevent the virus from spreading to others.

The clinical trial included 545 patients in 752 households who were treated with either the Xofluza or placebo.

A press release on the study noted that only 1.9% of uninfected household contacts who took the drug contracted the flu, compared with 13.6% of those who received a placebo.

Researcher Frederick Hayden, MD, from the University of Virginia School of Medicine, told MD/alert that the study addressed not only how effective the drug was in protecting others from developing the flu, but also how susceptible people might be to other viruses while taking the drug.

“Clearly, a single dose of baloxavir was highly effective in protecting contacts in the household from developing clinical influenza. This was not a surprise because we’ve known that other agents like oral oseltamivir or inhaled zanamivir are also highly protective," Hayden said.  

The frequency of adverse events was similar between the two groups, with 22% of those in the treatment arm experiencing symptoms like headaches and nausea, compared to 20.5% in the placebo arm.

Another significant difference, according to Hayden, was the fact that previous studies have used treatments that required taking medication for 7 to 10 days, whereas this study was a single dose of the drug compared to placebo.

“The overall level of protection that we saw against clinical influenza was 86%. Very substantial. In fact, somewhat higher than observed with flu vaccines," Hayden said. "We saw protection not only in adults but also with children. Also, irrespective of whether the participants had received flu vaccines in that season.”

While flu vaccines are the primary means of protection against a person contracting the flu, Hayden said this is another strategy for reducing the risk, especially for someone at high risk.

“You have to keep in mind, of course, our flu vaccines are suboptimal in their protection," Hayden said. "They certainly help, but they, unfortunately, are not as highly protective as we would like. Especially if someone’s in a group where there is a higher risk of influenza complications, that is a strategy if there is an exposure that could be used to try to reduce their risk further. It also tells us that if it works in a setting like a household, which is a fairly demanding one in terms of an antiviral for prophylaxis, that there’s good prospects for its use in other situations, for example, outbreaks in chronic care facilities, or in the hospital setting, which are not uncommon unfortunately with influenza.”

There is still more research to be done in this area, according to Hayden, including several studies looking at combining Xofluza with other antiviral drugs to increase the effectiveness of the treatments, while also reducing the risk resistance for some patients.

There are other drugs being developed that researchers hope will lead to quicker recovery and a reduction in complications.