Question explored with the scientific record
what is the biggest side effect of new shingles vaccine
The biggest side effect of the new shingles vaccine (Shingrix) is not a rare medical event—it is the predictable, intense reactogenicity that makes about 8 in 10 people feel sick for a day or two.
The evidence is clear that this is a reactogenic vaccine. In the large ZOE-50 trial, 79.1% of Shingrix recipients reported injection-site pain versus 11.2% in the placebo group [5]. A 2024 meta-analysis of immunocompromised adults found that local adverse events were 7 times more likely with Shingrix than placebo, and grade 3 (severe) local events were 31 times more likely [2]. A 2025 real-world study of 675 people reported that 44% had some adverse event after vaccination, with local reactions in 39% of doses and systemic reactions in 15% [1]. The most common complaints are fever, chills, headache, and muscle pain [4].
Serious side effects are much less common. In the ZOE trials, serious adverse event rates were similar between vaccine and placebo groups (about 9% in each) [5]. A large VAERS analysis covering 2017–2024 found that only 2.9% of Shingrix reports met the FDA definition of serious, compared to 27.6% for the older live vaccine [4]. There is a small Guillain-Barré syndrome signal: a self-controlled case series found about 3 extra cases per million doses within 42 days [6], and a Medicare analysis showed a relative risk of 2.34 that had not yet been chart-confirmed [7]. For people with autoimmune conditions, a VAERS study found a flare risk with a reporting odds ratio of 3.0, with most flares occurring within 3 days [3].
| Side effect type | How common it is | Source |
|---|---|---|
| Injection-site pain | ~79% of recipients | [5] |
| Fever, chills, headache | ~15–18% of reports | [4] |
| Any serious adverse event | ~2.9% of reports (similar to placebo) | [4] |
| Guillain-Barré syndrome | ~3 extra cases per million doses | [6] |
| Autoimmune disease flare | Elevated reporting ratio (3.0) | [3] |
My call: For most people, the main side effect is a day or two of feeling flu-like and sore. The serious risks are real but rare. Confidence: high for reactogenicity, moderate for the rare serious events.
Sources used 7
-
Safety profile and medium- to long-term protection of the Recombinant Zoster Vaccine (RZV) in a cohort of high-risk patients: real-world data from a General Hospital in Southern Italy, 2021–2025
A prospective real-world study in a Southern Italian hospital evaluated the safety, disease-flare potential, and medium-to-long-term protection against herpes zoster after Recombinant Zoster Vaccine (RZV) in a medically diverse, vulnerable adult population, finding acceptable sa…
DOI: 10.1080/14760584.2025.2589216 -
Systematic review and meta-analysis of recombinant herpes zoster vaccine in immunocompromised populations
In a meta-analysis of 7 RCTs in immunocompromised adults, recombinant zoster vaccine reduced herpes zoster incidence by 81% versus placebo and increased humoral and cellular immune responses, with higher local/general reactogenicity but no difference in unsolicited or fatal adve…
DOI: 10.1371/journal.pone.0313889 -
Risk of autoimmune disease flares after recombinant zoster vaccine: A vaccine safety analysis based on the Vaccine Adverse Event Reporting System database
This VAERS-based study quantified the risk of autoimmune-disease flares after recombinant zoster vaccination across five diseases (RA, MS, IBD, psoriasis, SLE), finding a positive safety signal with higher risk in SLE and most flares occurring within 3 days, highlighting the nee…
DOI: 10.1080/21645515.2025.2590257 -
Safety profile of herpes zoster vaccines in the United States: a descriptive and disproportionality analysis of adverse events reported to the vaccine adverse event reporting system (VAERS), 2017–2024
In 69,822 US VAERS reports (2017-2024), herpes zoster vaccine adverse-event reporting was dominated by transient reactogenicity and injection-site reactions, with serious reports uncommon overall (6.6%) and for Shingrix (2.9%) but more frequent for Zostavax (27.6%), largely driv…
DOI: 10.3389/fmed.2026.1920596 -
Zoster Vaccine Recombinant, Adjuvanted
In a narrative review of clinical trial data, adjuvanted recombinant zoster vaccine (Shingrix) showed high efficacy against herpes zoster and postherpetic neuralgia in adults 50 years and older, with mainly transient local and systemic reactions.
DOI: 10.1177/0018578718767103 -
Prevention of Herpes Zoster: A Focus on the Effectiveness and Safety of Herpes Zoster Vaccines
This narrative review finds real-world vaccine effectiveness of about 46% for live zoster vaccine and about 85% for recombinant zoster vaccine, with mostly local reactions and a small Guillain-Barré syndrome signal to monitor.
DOI: 10.3390/v14122667 -
Update From the Advisory Committee on Immunization Practices
ACIP's June 2019 meeting update reports vaccine policy votes on HPV, pneumococcal, influenza, hepatitis A, and meningococcal vaccines, plus measles, zoster, and dengue vaccine surveillance and trial evidence.
DOI: 10.1093/jpids/piz058