ACIP Narrowly Recommends Shingrix for Shingles Over Zostavax

October 25, 2017

The federal government's Advisory Committee on Immunization Practices (ACIP) voted 8 to 7 today to recommend a new recombinant and adjuvanted herpes zoster vaccine (Shingrix, GlaxoSmithKline) over a live, attenuated virus version (Zostavax, Merck) for adults 50 years of age and older.

It was not as if the ACIP, part of the Centers for Disease Control and Prevention (CDC), as a whole lacked confidence in Shingrix or disputed that it was far more effective than Zostavax. Panel members voted 14 to 1 to recommend the new vaccine for immunocompetent adults aged 50 years and older, the same indication in last week's approval of Shingrix by the US Food and Drug Administration. And the group voted 12 to 3 in favor of immunizing these same adults with Shingrix even if they already had been vaccinated with Zostavax, which is approved by the US Food and Drug Administration for adults ages 50 years and older, but recommended by the ACIP for adults aged 60 years and older.

However, the ACIP split almost evenly on the preference question, with the debate centered on how much caution to take with a brand-new vaccine. Several ACIP members advocated collecting safety data on Shingrix for a year or 2 and waiting to see whether supplies proved adequate before endorsing it over Zostavax. Sandra Fryhofer, MD, a liaison representative for both the American Medical Association and the American College of Physicians, noted that the adjuvant in Shingrix that boosts the immune response "has never been out in the real world before."

"It does seem to be a little bit impulsive," Dr Fryhofer said about giving the vaccine a preferential recommendation, adding later, "I do know how wonderful this vaccine is."

However, ACIP members who voted to steer clinicians to Shingrix suggested it would be irresponsible not to acknowledge its superiority over Zostavax, and to allow more patients to suffer with shingles in the process.

"Physicians look to us to make recommendations based on the evidence in front of us," said Kelly Moore, MD, MPH, director of the immunization program in the Tennessee Department of Health. Similar to others, Dr Moore said the ACIP could retract a preferential recommendation if Shingrix did not live up to expectations.

Right now, those expectations are high. The ACIP heard from CDC epidemiologist Kathleen Dooling, MD, MPH, that although the two vaccines have not underdone head-to-head trials, the estimated efficacy of Shingrix significantly tops that of Zostavax across all age groups.

Table. Efficacy Estimates for Shingrix and Zostavax

  Ages 60 to 69 Years Ages 70 to 79 Years Older Than 80 Years
Shingrix 97% 91% 91%
Zostavax 64% 41% 18%
Source: CDC

In addition, Dr Dooling said the efficacy of Shingrix appears to wane at a slower rate than that of Zostavax during the first 4 years of use.

An ACIP workgroup noted some possible drawbacks with Shingrix. Although Zostavax requires only one dose, Shingrix requires two, which could dampen patient uptake. Also, Shingrix is more reactogenic — think injection site soreness and fever. Despite these caveats, most members of the ACIP workgroup supported a preferential recommendation, and the ACIP followed suit, but narrowly so.

"This certainly is the closest vote in my experience at the ACIP," said ACIP Chair Nancy Bennett, MD, a professor of medicine and public health sciences at the University of Rochester in New York. "This discussion has been...very good, very transparent, very clear, but it's hard to have a divided committee."

Follow Robert Lowes on Twitter @LowesRobert

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