Zoster vaccine: is newer better?

Clinical question

Is there a difference in efficacy between the new, recombinant zoster vaccine (RZV) and the live zoster vaccine (LZV)?

Bottom line

Recombinant zoster vaccine appears more efficacious than LZV. Over 3 years, RZV prevents 1 additional case of herpes zoster (HZ) for about every 40 patients treated compared with 1 for every 60 to 70 with LZV. Both vaccines decrease the risk of postherpetic neuralgia. Recombinant zoster vaccine is more expensive and requires 2 injections whereas LZV only requires 1.

Evidence

There were 2 industry-supported placebo-controlled RCTs of RZV in immunocompetent patients without previous zoster infection or vaccine.^1,2 Authors calculated numbers needed to treat (NNTs) (assuming linear disease rates) at 3 years to indirectly compare to LZV.

• Studies of efficacy against HZ showed the following:

  • -In adults older than 50 years (N = 15 411; mean age 62), 0.08% had HZ with RZV versus 2.7% with placebo (NNT of about 40).¹ In a comparable live-vaccine RCT, the NNT was about 70.^3,4

  • -In adults older than 70 years (N = 13 900; mean age 76), 0.4% of patients had HZ versus 3.5% with placebo (NNT of about 40).² In a comparable live-vaccine RCT (patients ≥ 60 years), the NNT was about 60.⁵

• Studies of postherpetic neuralgia showed the following:

  • -For all ages, RZV had an NNT of 333 at 3.8 years or 422 at 3 years.^1,2 Live vaccine^3,5 had an NNT of about 360.

  • -For those older than 70 years, RZV had an NNT of 335^1,2 and LZV had an NNT of 260.⁵

• Serious adverse events occurred in 1.1% of those who had RZV, 1.9% of those who had LZV, and 1.3% of those who had placebo.^1,5

• Limitations with RZV studies were that blinding was questionable.^1,2 No head-to-head RCTs comparing LZVs and RZVs with clinical outcomes exist. No RCTs with clinical outcomes exist of patients who previously had any zoster vaccine or HZ.

Context

• Recombinant zoster vaccine differs from LZV in that 2 doses, 2 to 6 months apart are needed for RZV versus 1 for LZV.^6,7 Recombinant zoster vaccine costs about 40% more (about $250 vs $180 for LZV).⁸

• Current recommendations in Canada⁹ are to offer RZV to patients 50 years or older who previously received LZV or previously had HZ. In the United States,⁷ in those aged 50 to 59 years, RZV is recommended regardless of zoster infection or vaccine history; in those older than 60 years, either vaccine is given.

• Neither vaccine is recommended for pregnant patients.^6,7,9 Recombinant zoster vaccine might be considered in immunocompromised patients.⁹

Implementation

Annual rates of HZ increase with age, from about 4 in 1000 in those aged 40 to 64 to about 7 in 1000 in those 65 and older.¹⁰ Postherpetic neuralgia develops in 5% to 30% of HZ patients and also increases with age.¹¹ Risk of HZ recurrence ranges from 2% to 6%.¹¹ Patients who are or will be immunocompromised have a higher baseline and recurrence risk and should be encouraged to be vaccinated with RZV.⁹ If vaccinating patients who have had HZ or have received LZV, wait 1 year.⁹ Indirect comparison suggests, compared with LZV, 112 patients would have to be vaccinated with RZV to prevent 1 additional case of HZ.¹²