A team of researchers has posted a study that uses computer modelling to compare how long immune responses to the shingles vaccine Shingrix hold up in different age groups. Their simulations found that younger groups kept stronger responses over time than older ones, and that the difference did not fade away1. The paper, posted on 12 November 2026, is a preprint, which means it has not yet been checked by other scientists through peer review1.
The researchers also used the model to try out different vaccine schedules for older people. In those simulations, an extra dose given 6 to 12 months after the second dose seemed to narrow the age gap in antibody levels1. The authors describe these runs as exploratory. No one has tested this schedule in people as part of this work.
What the researchers did
The study is by Easlick T, De La Rosa G, Gantt S, Qin H, Shelton LR, Skibinski D and Craig M1. Their starting point is a simple question: how long does the protection from a vaccine last, and does that change as people age? They point out that this matters most in older populations, where immunosenescence (the gradual changes the immune system goes through with age) may change how the body responds to a vaccine1.
The team looked at two parts of the immune response after Shingrix. One is a type of helper immune cell, called CD4+ T cells, that reacts to gE. The other is antibodies against gE1. gE stands for glycoprotein E, the protein from the shingles virus that the vaccine is built around2.
After any vaccine, immune responses rise to a peak and then drop. The researchers split this decline into two stages: a “contraction” phase, when levels fall from their peak, and a “persistence” phase, when they settle at a longer-lasting level1. They wanted to measure how both stages differ with age.
How the computer model works
The team built what it calls a semi-mechanistic model. In plain terms, this is a set of equations that mimics how immune levels rise and fall, partly based on how the immune system is thought to work1. They used it to create “virtual populations”: large groups of simulated people who differ from one another in how high their immune response peaks and how fast it wanes1.
To compare age groups, the researchers made a new measure they call an “age-related immune advantage.” It answers a simple question at each point in time: if you pick one younger person and one older person at random, how likely is it that the younger one has the stronger immune response1? They checked this measure across several simulated populations1.
The result, the authors write, was “clear and sustained” age-related differences in both the T cell and antibody responses, with younger age groups consistently showing higher responses1.
What earlier studies of the vaccine showed
The new model sits on top of years of trial data. A 2018 study in The Journal of Infectious Diseases, covered by Dermatology Times, followed people who had received two doses of the vaccine in two clinical trials: one in adults aged 50 or older and one in adults aged 70 or older2. Antibody responses were measured in 3,293 adults and T cell responses in 466 adults2.
In that study, 97.8% of vaccine recipients developed an antibody response, compared with 2% of people who got a placebo (a dummy shot)2. Three years after the second dose, antibody levels were still above the response threshold in 77% of those vaccinated2. The T cell response rate was 93.3% one month after the second dose, fell to 57.2% at 12 months, and then held steady through three years2.
On age, the earlier investigators wrote:
“Humoral responses were elevated in all age groups, with anti-gE geometric mean concentrations only slightly smaller in participants 70 years and older throughout the 36 months of observation.”
That quote appears in the Dermatology Times report2. “Humoral” refers to antibodies. The report also said the vaccine’s efficacy was about 90% for all age groups2. Lead researcher Tony Cunningham, of the Westmead Institute for Medical Research in Sydney, said at the time that he expected the protection to “last much, much longer” than the three years studied2.
So the earlier data already hinted at a small age gap in antibody levels. The new preprint tries to put numbers on that kind of gap over time, using a model rather than a new group of patients.
What the study does not show
Several limits matter here.
- It is not peer reviewed. The paper is a preprint, so its methods and results have not been checked by independent experts1.
- It measures immune levels, not illness. The model tracks T cells and antibodies1. It does not report how many people got shingles. A lower immune measure in an older group does not, by itself, show how much protection that group has against disease.
- The booster idea is a simulation. The extra dose 6 to 12 months after the second shot was tested only inside the model, and only shown to possibly reduce age differences in antibody patterns1. The abstract does not say it changed the T cell gap or the risk of shingles.
- Details are missing from the summary. The abstract does not say which data the model was built on, exactly which age groups were compared, or how big the differences were. Readers will need the full paper for those details.
Who is behind it
The preprint lists seven authors1. The summary available to Biohack does not state their institutions, who paid for the work, or whether any author has ties to the vaccine’s maker. Those details usually appear in the full paper, and readers should check them there.
How it fits the field
Working out how fast a vaccine’s protection fades is a hard problem across vaccine science. A separate 2025 statistics paper on COVID-19 vaccines notes that knowing how vaccine effectiveness changes over time helps health officials decide whether and when to offer shots3. It gives flu as an example: evidence that flu vaccine protection wanes supports vaccinating high-risk groups closer to flu season3.
That same paper warns that common ways of estimating waning can be biased, even in randomized trials, and can make protection look like it fades faster than it really does3. That work is about counting infections, not modelling immune levels, so it does not apply directly to the Shingrix preprint. But it shows why researchers are trying new methods, including mathematical models, to study how long vaccines last.
The Shingrix authors say their work shows how this kind of modelling can help separate out age-related differences in vaccine results and point toward schedules tailored to age1.
What to watch next
- Whether the preprint passes peer review and is published in a journal, possibly with changes.
- Whether the full paper reports the size of the age gaps and the data the model was built on.
- Whether any clinical study tests an extra dose in older adults and measures both immune levels and shingles cases.
For now, the study adds a modelled picture of how immune responses to the vaccine differ by age. It does not change what is known about how well the vaccine prevents shingles, and it is not a basis for changing anyone’s vaccine schedule.
