The vaccine Shingrix prevents shingles, and if people do contract the virus, it reduces the severity of illness, two company-funded studies suggest.

Shingles, also known as herpes zoster, typically develops in older adults who had chicken pox, or the varicella-zoster virus, when they were younger. Its hallmark is a painful rash, which clears up within a month in most cases. In some instances, however, it leads to nerve pain that can linger for much longer and make it harder for people to manage daily tasks.

“We knew that patients who had not received the shingles vaccine, and then suffered a shingles outbreak as well as the pain related to it, would have had their quality of life negatively impacted,” said Erin Adams, a researcher at the Bernard J. Dunn School of Pharmacy at Shenandoah University in Fairfax, Virginia.

“The first shingles vaccine, Zostavax, did show evidence that it reduced the burden of illness and postherpetic neuralgia if a patient ended up getting shingles post vaccination,” Adams, who wasn’t involved in the study, said by email. “It had been theorized that the Shingrix vaccine could lessen the symptoms of the virus itself, but we did not have evidence of how patients who received the Shingrix vaccine and still had a shingles outbreak would respond or what the impact would be on their quality of life before this study was published.”

For the study, a research team including several employees of GlaxoSmithKline, the company that sells Shingrix, compared how often people given Shingrix and or a placebo got shingles, how much pain they endured, and how much they felt the illness contributed to a worse quality of life.

In one late-stage trial, 9 of 7,340 people given Shingrix developed shingles, compared with 254 of 7,413 participants who received a placebo. In another late-stage trial, 25 of 8,250 people given Shingrix developed shingles, compared with 284 of 8,346 subjects who received a placebo.

Researchers calculated that the vaccine was 98 percent effective at reducing the burden of illness in people who did get shingles in one trial, and 92 percent effective at reducing the burden of illness from shingles in the other trial.

In adults 80 and older, the vaccine was just 82 percent effective at reducing the burden of illness, but the absolute amount of reduction was higher in these participants than it was for younger people in the trials.

People who got Shingrix and still developed the virus also reported lower pain over the first 28 days of infection than people who received a placebo, but the difference between the groups wasn’t statistically meaningful on all of the days studied.

One limitation of the study is that the high level of vaccine effectiveness may have left few too people with shingles to detect meaningful differences between outcomes for vaccinated and unvaccinated participants, the authors note in The Journals of Gerontology Series A. The study authors declined requests for comment.

Still, the overall efficacy of the vaccine in reducing the burden of illness, interferences in activities of daily living was greater than 90 percent in patients 50 and older and in a pooled analysis of patients 70 and older, Adams noted.

“The study results are important to note for patients because not only does the vaccine help prevent shingles but it also shows that for patients who get shingles, despite receiving the vaccine (since no vaccine is 100% effective), that their quality of life is less impacted and pain scales are lower in patients compared to those who didn’t get the Shingrix vaccine,” Adams said.

Shingrix won U.S. regulatory approval in 2017 to help prevent shingles in adults 50 and older.