The COVID vaccine worked better in toddlers than in teenagers

In June 2024, the CDC's Advisory Committee on Immunization Practices
recommended **2024–2025 COVID-19 vaccination for everyone aged 6 months and
over**, for additional protection against severe COVID-19.

This study measured what that produced in children, across a **multisite
network covering nine states**, between **29 August 2024 and 2 September
2025**.

The result

**Vaccine effectiveness against COVID-19–associated emergency department or
urgent care visits, among immunocompetent children:**

Both compared with children who did not receive a 2024–2025 vaccine.

Why the younger group does better

That comparison is the key to reading these numbers, and it is also why the
two figures differ.

By 2024, most older children had **previous vaccination, previous infection,
or both**. The unvaccinated comparison group in the 5–17 band therefore was
not unprotected — it had substantial existing immunity, and the season's
vaccine was adding to an already-raised floor.

The youngest children had less of that history. There was more room for the
vaccine to add protection, and the measured effect is larger.

So 76% and 56% are not a statement that the vaccine works better in toddlers.
They are a statement about **how much additional protection it gave, on top of
what each group already had.**

What the study concludes

**In a population where some people already had protection from previous
vaccination, previous infection or both, 2024–2025 COVID-19 vaccination gave
children additional protection** against COVID-19–associated emergency and
urgent care visits.

Additional is the operative word, and it is the honest framing for any vaccine
given into a population that has already met the pathogen.

*Source: Irving SA, Rowley EAK, Chickery S, et al. Effectiveness of 2024–2025
COVID-19 Vaccines in Children in the United States — VISION, August 29,
2024–September 2, 2025. MMWR, Centers for Disease Control and Prevention.*