Impact of shingles vaccine tolerability on initiation and completion of the two-dose series in adults 50 years and older

Shingles is a painful disease, commonly affecting older adults, and caused by the reactivation of the Varicella Zoster Virus (VZV). The currently available recombinant zoster vaccine, brand name Shingrix (SHX), has relatively low uptake. This study aimed to quantify the possible impact on initiation and completion of the two-dose SHX series related to concerns of SHX side effects among adults aged 50 and older. We implemented both a nationally representative sample in the US (N = 1004) and a hospital-based sample from Michigan (N = 566). In the national sample, 206 (17 %, 95 % CI: 14 %, 20 %) respondents had 2 doses of SHX, 52 had 1 dose (4 %, 95 % CI: 3 %, 5 %), and 555 (61 %) were unvaccinated (95 % CI: 57 %, 65 %). In the Michigan sample, concerns about tolerability were significantly associated with the number of SHX doses received (p < 0.0001). Among those who had not received any doses, 46 % reported being concerned about tolerability, compared to 39 % among those with 1 dose, and only 22 % of those who had received two doses. Individuals concerned about side effects were 1.22 times more likely to not receive any dose (95 % CI: 1.11, 1.34), and 1.83 times more likely to receive only one dose (95 % CI: 1.26, 2.65) than to receive the full two dose series. That tolerability was the leading reason for both initiation and completion of the SHX vaccine series underscores the need for increased attention on perceptions about vaccine tolerability, as separate from safety, in the introduction and promotion of vaccines. Addressing concerns about vaccine tolerability could improve SHX coverage, ultimately reducing the burden of shingles in older populations.