Expanding Convenient Access to the Flu Vaccine for Young Children

To estimate the effectiveness of the flu vaccine in reducing pediatric health care visits and costs, we draw on administrative records from a large Southern California HMO (Kaiser Permanente) for doctor’s office visits and vaccinations, covering roughly 148,639 children ages 2–5 per year from 2008–2016. We use statewide California administrative data for ED visits and inpatient stays. We focus on children ages 2-5 because they incur higher per-capita flu-related health care costs than any group except seniors.

Our estimates come from a natural experiment. Because the seasonal vaccine becomes available only in early fall, children whose annual well-child visit happens to fall just after it arrives are far more likely to be vaccinated than otherwise-similar children born a few months earlier. Comparing these groups lets us isolate the vaccine’s causal effect and avoid the selection bias that confounds studies that simply compare vaccinated with unvaccinated children. Three findings stand out:

The pediatric flu vaccine meaningfully reduces real-world health care use. Among outpatient visits, vaccination prevented essentially all flu-coded office visits and about three-quarters of flu- or influenza-like illness (ILI) visits. For every 100 children vaccinated, there are about 2.1 fewer flu-coded and 1.9 fewer flu-or-ILI visits than if they were unvaccinated. Its effect on all respiratory-illness visits was far larger—about 25 fewer per 100 children, or roughly a quarter to a third of them—five to ten times the reduction found in clinical trials, which count only lab-confirmed flu.

Among ED visits, we observed smaller but statistically significant reductions—about 0.13 fewer flu-related ED visits and 0.25 fewer flu-or-ILI ED visits per 100 children vaccinated.

We did not detect a reliable effect on hospitalizations. This is unsurprising, since hospitalizations in this age group are about 100 times rarer than office visits, leaving too few cases to measure an effect.

The flu burden is substantially undercounted. The gap between the respiratory-visit effect (about 25 per 100) and the flu-coded effect (about 2 per 100) implies that most flu-caused visits are never recorded as flu. Most respiratory visits do not lead to a flu test. Moreover, rapid tests miss many true cases, and symptom-based definitions like ILI exclude many flu-related coughs. As a result, standard estimates of flu’s public-health burden are understated, and cost-benefit analyses that count only coded-flu visits undervalue the vaccine.

Convenience is a powerful, underused lever for increasing vaccinations. We find that having a well-child visit while the vaccine is available raises the probability of vaccination by 23.4 percentage points. The 23.4-percentage-point convenience effect is several times larger than the response to monetary incentives documented in other settings: field experiments imply that raising uptake by 10 points via cash requires roughly $33–$57 per person (Bronchetti et al. 2015, Campos-Mercade et al. 2021), so the convenience of a well-timed visit is equivalent to an incentive on the order of $77–$133. This timing-driven gap in vaccination is larger than the gaps associated with a child’s usual source of care, insurance type, income, or race and ethnicity. The only factor that predicts a bigger gap is having no insurance at all.

Federal and state lawmakers should make it more convenient for young children to receive the pediatric flu vaccine by expanding where and when they can be vaccinated. Because uptake is driven far more by convenience than by price, policy should widen access points rather than subsidize demand.

Specifically, in states where not currently permitted, lawmakers should authorize and encourage pharmacies to vaccinate young children. Pharmacies are more numerous, offer longer hours, and do not require an appointment, making them a natural way to decouple vaccination from the pediatric visit. Much of that access currently rests on a temporary federal authority set to expire at the end of 2029 (see below). To keep it from lapsing, Congress or HHS should make pharmacists’ pediatric vaccination authority permanent, and states should write it into their own scope-of-practice laws.

We combine our per-visit utilization effects with published per-visit costs (Putri et al. 2018, inflated to 2021 dollars) of about $134 per pediatric flu outpatient visit, $1,011 per ED visit, and $8,596 per inpatient stay.

Applying the estimated reductions in respiratory-illness visits yields cost reductions of about $3,298 (outpatient), -$234 (ED), and $1,624 (inpatient) per 100 vaccinated children—a combined $4,688 per 100 vaccinated children.

Scaling the per-child savings (about $47 per vaccinated child) across the roughly 20 million U.S. children ages 2–5 implies about $938 million in avoided medical costs per year if the entire cohort were vaccinated. About half of that ($469 million) is already realized at the current 50% vaccination rate, so raising coverage from 50% toward 100% would save on the order of an additional $469 million per year. The benefit is about $50 per vaccination, more than double the roughly $21 combined cost of purchasing (about $14/dose) and administering (about $7) the vaccine.

These savings would accrue to whoever pays for the averted care—primarily Medicaid/CHIP and employers or commercial insurers, and families through lower out-of-pocket spending. Our estimate is a lower bound: it excludes the value of avoided school absences and parental sick days and the spillover benefits of reduced transmission, all of which would raise the benefit-cost ratio.

To caveat, the headline figure relies on the larger respiratory-illness point estimates; the inpatient component in particular is not statistically robust, so the true medical-cost savings could be smaller. Per-visit costs come from a single source, and the effectiveness estimates are drawn from one large California HMO plus statewide California data, which may limit national generalizability. The estimate also does not net out the administrative cost of expanding access points.

Access to pharmacist-administered flu vaccination for young children is governed by an uneven state patchwork. All 50 states and DC permit pharmacists to administer flu vaccines, but the minimum age and levels of immunization authority vary widely (NASPA 2024). Beyond administration authority, some states may allow pharmacists to independently prescribe vaccines or delegate vaccine administration to a pharmacy technician. According to data from the National Alliance of State Pharmacy Associations and the American Pharmacists Association dated August 2024, 15 states allow pharmacists to administer the flu vaccine to individuals of all ages (NASPA 2024). Two states allow administration for individuals six months and older, one allows it for ages 2 and older, and 13 allow it for ages three years and older. The remaining states set higher minimum ages.

A temporary federal authority currently overrides this patchwork. Under the Public Readiness and Emergency Preparedness (PREP) Act, the current declaration lets pharmacists nationwide administer seasonal flu (and COVID-19) vaccines to children ages 3–18—preempting stricter state limits—through December 31, 2029 (its 12th Amendment, effective January 1, 2025). If this authority lapses, the state patchwork will govern access again.