Recombinant shingles vaccine linked to reduced risk for dementia

Key takeaways:

• Recombinant herpes zoster vaccine recipients had lower risk for developing dementia compared with those who received live vaccine.
• The recombinant vaccine provided a more robust protective effect in women.

Adults who received the recombinant zoster vaccine had a significantly lower risk for dementia over the next 6 years compared with live vaccine recipients, study results published in Nature Medicine revealed.

Those who received the recombinant vaccine for herpes zoster, commonly known as shingles, also exhibited lower risk for dementia compared with influenza and diphtheria-tetanus vaccines, researchers reported.

The recombinant shingles vaccine has previously been tied to risk reductions for several adverse health outcomes, including death and stroke.

Recent analyses “have generated substantial interest in the potential protective effect of shingles vaccination against dementia,” according to Maxime Taquet, PhD, a National Institute for Health and Care Research clinical lecturer, and colleagues.

“However, most of these studies have compared vaccinated with unvaccinated cohorts, a design prone to selection bias, including healthy vaccinee bias.”

In the current study, the researchers — using electronic health record data — propensity-matched 103,837 individuals who received the first dose of a shingles vaccine between November 2017 and October 2020 to 103,837 individuals who received their first dose between October 2014 and September 2017.

Overall, 95% of individuals who received their first dose between November 2017 to October 2020 received the recombinant vaccine, whereas 98% of those who received their first dose between October 2014 and September 2017 received the now-disused live vaccine.

The researchers found that those who received the recombinant vaccine had a lower risk for dementia over the next 6 years (restricted mean time lost [RTML] ratio = 0.83; 95% CI, 0.8-0.87) vs. those who received the live vaccine.

Researchers reported a relationship between the recombinant vaccine and a a 17% increase in time free of a dementia diagnosis, which equaled 164 additional days lived without a dementia diagnosis in those affected.

These associations occurred in both men and women, but study investigators noted a greater protective effect among women (22% vs. 13% more time lived without a diagnosis).

Still, “the consistency of the association in both sexes is important from a public health point of view,” Taquet and colleagues noted.

Those vaccinated with the recombinant vaccine were also less likely to have a shingles infection in the following 6 years (RTML ratio = 0.65; 95% CI, 0.61-0.69).

The researchers explained that the mechanisms behind the found associations remain unclear, although they offered several theories.

“One explanation is that it protects against herpes infection, which itself causes dementia,” they suggested. “Additionally, the recombinant vaccine contains immunostimulants and these could contribute to the effect on dementia risk.”

Study investigators noted a few study limitations.. For example, “being diagnosis-free does not imply being disease-free as there can be delays in diagnosis,” Taquet and colleagues wrote.

They also did not investigate associations between dementia risk and multiple vaccine doses.

Ultimately, the results “provide [a] rationale for a randomized control trial aiming to confirm them and inform future cost effectiveness analysis of the recombinant vaccine,” the researchers concluded.