With limited influenza vaccine availability, which group should be prioritized: school children, pregnant women, adults with idiopathic hypertension, or children with iron‑deficiency anemia?

Priority Group for Limited Influenza Vaccination: Pregnant Women

When influenza vaccine supplies are limited, pregnant women should receive the highest priority for vaccination. 1, 2

Evidence-Based Priority Framework

The Advisory Committee on Immunization Practices (ACIP) has established a clear hierarchy for vaccine allocation during shortages, placing pregnant women in the top-tier priority group alongside:

• Persons aged >65 years with and without comorbid conditions 1
• Residents of long-term care facilities 1
• Persons aged 2-64 years with comorbid conditions 1
• Children aged 6-23 months 1
• Healthcare personnel who provide direct patient care 1

Why Pregnant Women Are Highest Priority

Pregnant women face substantially elevated morbidity and mortality risks from influenza. The relative risk for hospitalization escalates dramatically from 1.4 at weeks 14-20 of gestation to 4.7 at weeks 37-42 compared to postpartum women. 1, 3 Third-trimester pregnant women have hospitalization rates (250/100,000) comparable to non-pregnant individuals with high-risk medical conditions. 1, 3

Historical pandemic data from 1918-1919 and 1957-1958 documented disproportionately high maternal mortality rates. 1, 3 Physiologic changes during pregnancy—including increased heart rate, stroke volume, and oxygen consumption; decreased lung capacity; and altered immunologic function—increase vulnerability to severe influenza complications. 1, 3

Vaccination during pregnancy provides dual protection: it reduces maternal risk of severe illness and provides passive immunity to infants up to 6 months of age who cannot yet be vaccinated. 1, 3, 4

Why Other Options Are NOT Priority Groups

School Children (Option A)

Healthy school-age children (generally 5-18 years) without underlying medical conditions are not prioritized when vaccine supplies are constrained. 2 Only younger children (6 months-4 years) or those with high-risk conditions receive priority status. 1, 2

Adults with Idiopathic Hypertension (Option C)

Isolated adult hypertension is explicitly excluded from the list of high-risk conditions that warrant priority vaccination. 2 Cardiovascular disease qualifies as a priority condition except when it presents solely as isolated hypertension. 2

Children with Iron Deficiency Anemia (Option D)

Iron-deficiency anemia in children alone does not qualify as a high-risk condition for influenza complications unless it is associated with chronic hematologic disorders such as hemoglobinopathies. 1, 2

Clinical Implementation

Vaccination can be administered at any time during pregnancy, including the first trimester. 1, 3 Studies of influenza vaccination in more than 2,000 pregnant women have demonstrated no adverse fetal effects. 1, 3 A systematic review and meta-analysis of 15 studies showed no association between congenital defects and influenza vaccination in any trimester. 3

The American College of Obstetricians and Gynecologists (ACOG) and ACIP recommend that all women who are pregnant or who might be pregnant during the influenza season receive inactivated influenza vaccine (IIV) because of the increased risk for serious illness and complications. 1, 3

Common pitfall to avoid: Do not delay vaccination waiting for pregnancy confirmation or to avoid the first trimester. 3 The safety profile is well-established across all trimesters, and early vaccination maximizes protection during the highest-risk period. 1, 3