Should old people keep taking the Covid jab even after 7 or 8 previous ones

After 7 or 8 doses, the evidence for further COVID-19 boosters in older adults is thin and contradictory, with no data on the specific question of a 9th or 10th shot.

The retrieved studies only cover up to a fourth or fifth dose [1][2][6]. One 2026 study of a highly vaccinated elderly cohort (median 11 doses) found that repeated Omicron boosters did broaden antibody breadth, but a major variant still escaped neutralization [6]. That is a lab readout, not proof of clinical benefit.

The best evidence for benefit comes from studies of the first booster in older adults. A 2023 Australian study of people 65+ found a bivalent booster reduced COVID-19 mortality by about 66% compared to no booster, but protection waned sharply after 90 days [1]. A 2026 Beijing study of adults 80+ reported booster effectiveness of about 64% against hospitalization and 79% against in-hospital death [2]. Both are observational, not randomized, and the Beijing study adjusted only for age and sex, not for the underlying health differences that drive who gets boosted [2].

The harms side is harder to quantify. A 2025 ecological analysis linked COVID vaccination rates to increased all-cause mortality within 5 weeks in US and European data, estimating about 0.04% vaccine-attributed deaths overall and higher rates in older age groups [3]. A 2026 critique of an Australian study argued that the claimed 51% reduction in all-cause mortality from vaccination is mathematically implausible, implying a 121% excess death rate in the unvaccinated that has never been seen in any historical data [4]. These are not direct evidence of harm from a 9th dose, but they show the safety signal is real and the benefit claims may be exaggerated by confounding.

The core problem: no study has compared people with 7+ doses to people with fewer doses on hard outcomes like hospitalization or death. The immune system does not simply keep improving with each shot. Repeated boosting can narrow the antibody repertoire (original antigenic sin) and shift immunity toward IgG4, a less effective antibody class [6]. In very old, frail people, the immune response to vaccination is already weaker and wanes faster [5][7].

My call: The evidence does not support continuing COVID-19 boosters past 7 or 8 doses in older adults. The benefit of the first few boosters was real but waning, and the added value of further doses is unstudied while the theoretical risks of immune imprinting and cumulative adverse events are real. Confidence: low — because the question itself has not been studied, not because the answer is unknown.