Efficacy and Safety of Vaccinations in Geriatric Patients: A Literature Review

Abstract

With the progressive lengthening of the average age of the population, especially in some countries such as Italy, vaccination of the elderly is a fixed point on which most of the public health efforts are concentrating as epidemic infectious diseases, especially those of the winter, have a major impact on the progression of severe disease, hospitalization, and death. The protection of the elderly against acute infectious diseases should not only limit mortality but also have a positive impact on the fragility of these people in terms of less disability and fewer care needs. However, vaccination of the elderly population differs in efficacy and safety compared to that of other population categories since aging and the consequent loss of efficiency of the immune system lead to a reduction in the immunogenicity of vaccines without achieving a lasting antibody coverage. There are various strategies to avoid the failure of immunization by vaccines such as resorting to supplementary doses with adjuvant vaccines, increasing the dosage of the antigen used, or choosing to inoculate the serum relying on various routes of administration of the vaccine. Vaccination in the elderly is also an important factor in light of growing antibiotic resistance because it can indirectly contribute to combating antibiotic resistance, reducing theoretically the use of those agents. Furthermore, vaccination in old age reduces mortality from infectious diseases preventable with vaccines and reduces the same rate of resistance to antibiotics. Given the importance and complexity of the topic, in this review, we will deal with the main aspects of vaccination in the elderly and how it can influence mortality and healthcare costs, especially in those countries where population aging is more evident. Therefore, we conducted a systematic literature search in PubMed to identify all types of studies published up to 31 May 2023 that examined the association between vaccination and the elderly. Data extraction and quality assessment were conducted by two reviewers (PC and TC) who independently extracted the following data and assessed the quality of each study.

Impact of ageing on homologous and human-coronavirus-reactive antibodies after SARS-CoV-2 vaccination or infection

“…Lower vaccine efficacy and effectiveness have been reported in elderly individuals, often attributed to immunoscenesence 19 , 20 . After two doses of COVID-19 vaccine, heterogeneity in immune response has been observed in both humoral and cellular compartments in different age groups 21 – 23 .…”

Enhancing vaccine effectiveness in the elderly to counter antibiotic resistance: The potential of adjuvants via pattern recognition receptors

“… 9–11 Strategies to improve vaccine effectiveness in the elderly include antigen discovery, improvements in vaccine programs (such as adjusting antigen dosage, modifying administration routes, and optimizing booster schedules), and the incorporation of adjuvants. 265 However, antigen discovery has its limitations, and even with booster vaccines in the elderly, effectiveness might not reach the levels seen in young adults. Therefore, the use of adjuvants could be the most dramatic means to increase vaccine effectiveness.…”

Aging amplifies a gut microbiota immunogenic signature linked to heightened inflammation

“…Older adults are exposed to antibiotics at higher rates as compared to young individuals. This is critical because older adults have higher rates of infection (Ciarambino et al, 2023) and antibiotic-induced perturbations to the gut microbiota have been directly linked with reduced vaccine efficacy in older adults who already suffer from reduced responses to vaccine (Ciarambino et al, 2023;Hagan et al, 2019). Our findings revealed notable variations in recovery from antibiotics in aged vs. young mice.…”