Effects of Oral Iron Supplementation on Vaccine Response in Iron Deficient Kenyan Women

Effects of Oral Iron Supplementation Before vs. at Time of Vaccination on Immune Response in Iron Deficient Kenyan Women

Iron deficiency (ID) anemia (IDA) is a global public health problem, with the highest prevalence in Africa. Vaccines often underperform in low- and middle- income countries (LMIC), and undernutrition, including ID, likely plays a role. Recent studies have shown the importance of iron status in vaccine response. Intravenous iron given at time of vaccination improved response to yellow fever and COVID-19 vaccines in IDA Kenyan women. Whether oral iron treatment would have a similar beneficial effect on vaccine response is uncertain. Also, timing of oral iron treatment needs further investigation.

The co-primary objectives of this study are to assess 1) whether IDA in Kenyan women impairs vaccine response, and whether oral iron treatment improves their response; 2) the timing of oral iron treatment to improve vaccine response (prior to vaccination vs at time of vaccination).

We will conduct a double-blind randomized controlled trial in southern Kenya to assess the effects of iron supplementation on response to three single-shot vaccines: Johnson & Johnson COVID- 19 (JJ COVID-19), the quadrivalent meningococcal vaccine (MenACWY) and the typhoid Vi polysaccharide vaccine (Typhim Vi). Women with IDA will be recruited and randomly assigned to three study groups: group 1 (pre- treatment) will receive 100 mg oral iron as ferrous sulfate (FeSO4) daily on days 1-56; group 2 (simultaneous treatment) will receive matching placebo daily on days 1-28, and 200 mg oral iron as FeSO4 daily on days 29-56; and group 3 (control) will receive matching placebo daily on days 1-56. Women in all groups will receive the JJ COVID-19 vaccine, the MenACWY and the Typhim Vi vaccine on day 28. Cellular immune response and serology will be measured at 28 days after vaccination in all groups.

Inclusion Criteria:

• Willing and able to give informed consent for participation in the trial
• Female aged 18-49 years
• Moderate anemia (Hb <110 g/L, but not severely anemic with Hb <80 g/L) • Iron deficient (ZnPP >40 mmol/mol haem)
• Anticipated residence in the study area for the study duration

Exclusion Criteria:

• Major chronic infectious disease (e.g., HIV infection);
• Major chronic non-infectious disease (e.g., Type 2 diabetes, cancer);
• Chronic medications;
• Use of iron-containing mineral and vitamin supplementation 2 weeks prior to study start;
• COVID-19 vaccine or confirmed COVID-19 infection within the past 2 years
• MenACWY vaccine in the past
• Typhoid vaccine in the past
• Pregnant (confirmed by rapid test during screening) or lactating.
• Malaria (confirmed by rapid test) à study start will be postponed