Effectiveness of influenza vaccination in the elderly in South Africa

Abstract

SUMMARYThis study primarily aimed to estimate the association between influenza vaccination and the occurrence of hospitalization for acute respiratory or cardiovascular diseases, or all-cause death during the influenza season in an elderly population in South Africa. We conducted a nested case-control study using data from a cohort of 45 522 elderly members of a private medical funding organization during the moderate 2004 influenza season. In 1282 (2 . 8%) subjects the combined outcome occurred and the influenza vaccination rate in controls was 15 . 4 %. After adjustments for measured confounders, vaccination was associated with a statistically significant reduction of 19% (95 % confidence interval 3 . 1-32 . 9) in the combined outcome. Post-hoc sensitivity analysis of the potential impact of potential healthy user bias showed that confounding, if present, could have caused this finding. Our data were inconclusive regarding the benefits of influenza vaccination in elderly persons in South Africa and given the low vaccine uptake, long-term follow-up is warranted.

Elevated Influenza‐Related Excess Mortality in South African Elderly Individuals, 1998–2005

“…The observed differences in excess mortality are not explained by differences in vaccination coverage between US (∼65%) and South African (15% of insured population in one study) elderly individuals, because influenza-associated mortality in US elderly individuals has remained constant since the 1980s, despite increased vaccination coverage [2,39]. Human immunodeficiency virus (HIV)/AIDS comorbidity is also probably not a contributing factor in persons aged у65 years, unless high HIV prevalence in younger populations is associated with increased intensity of influenza transmission in the community.…”

Considerations for Establishing Successful Coronavirus Disease Vaccination Programs in Africa

“…Influenza and pneumonia are the vaccines most commonly recommended for elderly persons, and studies on the uptake and effectiveness of these vaccines in Africa are few. Studies from South Africa show that elderly populations at risk for high mortality rates have reduced uptake of the influenza vaccine, indicating the need for more effective approaches to increase uptake and ultimately achieve population-level immunity (19). Compared with the influenza vaccine, which showed an efficacy of 30%-50% among persons ≥65 years of age and 70%-90% in children and younger adults, available data from 2 leading vaccine candidates (Pfizer-BionTech and Oxford-AstraZeneca) indicate an efficacy >90% in persons ≥65 years of age (15,16,18).…”

“…T he World Health Organization (WHO) declared the spread of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), the causative agent of coronavirus disease (COVID- 19), a pandemic in March 2020 on the basis of the rapid rate of increase in infections across many countries. As of May 9, 2021, ≈157 million cases and 3.2 million deaths had been recorded globally (1), a fi gure that continues to grow.…”

Afriflu2—Second international workshop on influenza vaccination in the African continent—8 November 2012, Cape Town (South Africa)

“…It should be pointed out that in the South African children’s study the vaccine was not well matched with circulating strains; nevertheless, over and above the mismatch, the immunogenicity in this population was intrinsically poor. In elderly South Africans poor effectiveness of influenza vaccination – 19.3% – was found in a small study in a health management setting [ 32 ].…”