Mass RZV vaccination from age 50 years may reduce HZ burden in HK

Mass vaccination with recombinant zoster vaccine (RZV) in adults ≥50 years of age is expected to considerably reduce the public health burden of herpes zoster (HZ) in Hong Kong compared with no vaccination or vaccination with zoster vaccine live (ZVL), according to a mathematical modelling study by researchers from the Chinese University of Hong Kong.

The researchers compared the public health impact of vaccination with RZV (two-dose vaccine) or ZVL (one-dose vaccine) and no HZ vaccination in adults ≥50 years of age by adapting the Zoster Economic Analysis (ZONA) model with Hong Kong–specific key model inputs and/or assumptions. The base case population involved 3.13 million adults aged ≥50 years in Hong Kong in 2020, which was divided into five age cohorts (age 50–59 years, 60–64 years, 65–69 years, 70–79 years, and ≥80 years). [Hum Vaccin Immunother 2023;19:2176065]

“Using data relevant to Hong Kong where available and updated RZV efficacy data based on 8 years of follow-up, our model predicted a high public health burden of HZ in Hong Kong in the absence of vaccination, which could be reduced with HZ vaccination,” the researchers noted.

In the base case population, 891,024 HZ cases (28.4 percent), 156,097 postherpetic neuralgia (PHN) cases (5.0 percent) and 38,755 HZ ophthalmicus (HZO) cases (1.2 percent) were projected to occur over the remaining lifetime without HZ vaccination.

In the mass vaccination setting with 40 percent coverage, RZV reduced the number of HZ, PHN and HZO cases by 23.0 percent, 20.5 percent and 21.9 percent, respectively, compared with no vaccination, while ZVL reduced HZ, PHN and HZO cases by 5.3 percent, 4.9 percent and 4.6 percent, respectively.

“RZV vaccination avoided 4–5 times the number of cases avoided with ZVL vaccination,” the researchers pointed out. “RZV was more efficient than ZVL, with a lower number needed to vaccinate [NNV] to prevent one case of HZ, PHN or HZO than ZVL [RZV: 7, 40 and 148, respectively; ZVL: 27, 163 and 709, respectively].”

Among all age cohorts, the greatest reduction in HZ, PHN and HZO cases was projected in those aged 50–59 years with the mass RSV vaccination strategy vs no vaccination or ZVL vaccination. Progressively fewer cases were projected to be averted in older age cohorts.

“The results remained robust in scenario and sensitivity analyses,” the researchers reported.

Furthermore, mass RZV vaccination was projected to prevent 20 additional HZ-related deaths compared with no vaccination and 19 additional HZ-related deaths compared with ZVL vaccination.

“HZ burden in Hong Kong is substantial. Among the two HZ vaccines currently available in Hong Kong, mass vaccination with RZV is expected to considerably reduce the public health burden of HZ among individuals ≥50 years of age compared with no vaccination or ZVL vaccination,” the researchers concluded.

“These results may support value assessment and decision-making regarding vaccination strategies for HZ prevention in Hong Kong,” they suggested.