Vaccine efficacy and iron deficiency: an intertwined pair?

Abstract

Vaccines are the most effective measure to prevent deaths and illness from infectious diseases. Nevertheless, the efficacy of several paediatric vaccines is lower in low-income and middle-income countries (LMICs), where mortality from vaccine-preventable infections remains high. Vaccine efficacy can also be decreased in adults in the context of some common comorbidities. Identifying and correcting the specific causes of impaired vaccine efficacy is of substantial value to global health. Iron deficiency is the most common micronutrient deficiency worldwide, affecting more than 2 billion people, and its prevalence in LMICs could increase as food security is threatened by the COVID-19 pandemic. In this Viewpoint, we highlight evidence showing that iron deficiency limits adaptive immunity and responses to vaccines, representing an under-appreciated additional disadvantage to iron deficient populations. We propose a framework for urgent detailed studies of iron–vaccine interactions to investigate and clarify the issue. This framework includes retrospective analysis of newly available datasets derived from trials of COVID-19 and other vaccines, and prospective testing of whether nutritional iron interventions, commonly used worldwide to combat anaemia, improve vaccine performance.

COVID-19-Related Brain Injury: The Potential Role of Ferroptosis

“… 146 Expert opinions indicate that it is advisable to correct the iron deficiency before administering the COVID-19 vaccine. 147 Iron is a nutrient required for immunity, and iron deficiency reduces the efficacy of vaccines. 147 However, no studies have investigated the role of the COVID-19 vaccine on ferroptosis.…”

COVID-19 vaccines in patients with cancer: immunogenicity, efficacy and safety

“…Cancer, and related symptoms such as treatmentassociated immunodeficiencies, cannot be easily overcome. However, patients with cancer might be particularly prone to vitamin and nutrient deficiencies for several reasons and some of these, such as iron deficiency, have been associated with an impaired immune response to vaccination 170 . So far, no data are available on the benefits of interventional dietary supplementation around the time of vaccination despite increasing evidence that vitamin D or vitamin A might be protective against severe respiratory infections [171][172][173][174] .…”

Host factors and vaccine efficacy: Implications for COVID‐19 vaccines

“…Micronutrient deficiencies may lead to impaired immune responses, resulting in weak vaccine response, 11 for example, evidence suggests that iron deficiency is associated with lower vaccine efficacy. 31 …”

“…There is evidence that iron deficiency may lead to poor vaccine responses. 31 Iron deficiency and anemia at the time of vaccination of children in Kenya have been reported as prognostic factors for weak response to some vaccines including diphtheria, pneumococcal, and pertussis. In addition, the use of iron supplements at the time of measles vaccination strengthened the vaccine immunogenicity.…”

“…However, iron deficiency appears to have a negative effect on the adaptive immune system and leads to poor vaccine response. 31 Iron is required for lymphocyte development, and homozygous mutations in Transferrin receptor protein 1 cause immunodeficiency and a decrease in memory B‐cell count in children. 30 , 32 …”