Flu Hit Children Hard and Early in 2022–23: A High-Severity Season for Under-18s

The 2022–23 flu season started in early October — earlier than most — and returned to pre-COVID levels. It ran alongside SARS-CoV-2 and RSV, with high child hospitalization rates in the Southeast and a limited shortage of the antiviral oseltamivir. CDC looked at how it hit children and teens under 18, compared with seasons from 2016–17 to 2021–22 (leaving out 2020–21, when there was almost no flu).

A high-severity season

CDC rates severity on three measures: the share of doctor visits for flu-like illness, the rate of lab-confirmed flu hospitalization, and the share of deaths due to flu, each compared with thresholds from past peak seasons. For children, all three peaked in the "high" range, making 2022–23 high severity — the fourth such season for children since the 2009 H1N1 pandemic. Visits and hospitalizations peaked in late November 2022; deaths peaked three weeks later and stayed high through December.

Outpatient visits for flu-like illness (A), flu hospitalization rates (B) and share of deaths due to flu (C) among children and teens under 18, with severity thresholds. CDC / MMWR

How many

• Children under 5 had higher rates than older children — their second-highest since 2016–17: 11,443 medical visits and 119 hospitalizations per 100,000.
• For 5–17-year-olds, visit and hospitalization rates were the highest of any season since 2016–17.
• Death rates were low, in line with past seasons: 1.2 per 100,000 under 5 and 0.5 at 5–17.

Flu-associated medical visits (A, C) and hospitalizations (B, D) among children under 5 and 5–17, 2016–17 to 2022–23. CDC / MMWR

Who was hospitalized

From October 1, 2022, to April 30, 2023, the Influenza Hospitalization Surveillance Network (FluSurv-NET) — covering about 9% of the U.S. population — recorded 2,762 flu hospitalizations under 18 (2,108 sampled with clinical data):

• median age 5; 57.4% boys; 50.5% had an underlying condition, most often asthma, neurologic disorders and obesity
• 95.4% influenza A — of those subtyped, 80.2% H3N2
• 57.1% of the season's child hospitalizations came in October and November — against 1.6%–6.8% in those months in earlier seasons
• 18.4% went to intensive care, 4.7% needed a ventilator, and 0.4% died in hospital — similar to past seasons

Too few vaccinated, too few treated

• Only 18.3% of hospitalized children had had a flu vaccine, against 35.8%–41.8% in earlier seasons. When child hospitalizations peaked (week ending November 26, 2022), just 41.9% of children aged 6 months to 17 years had been vaccinated nationwide (55.1% by season's end) — similar to 2021, but below 2019 (51.9%) and 2020 (49.7%).
• The vaccine itself worked: early estimates showed 68% protection against child hospitalization. The early start and low early coverage likely drove the high hospitalization rate anyway.
• 64.9% of hospitalized children with respiratory symptoms got antiviral treatment — similar to 2021–22 (61.5%) but below pre-pandemic seasons (80.8%–87.1%).

What to do

• Everyone 6 months and older without contraindications should get a flu vaccine every year, ideally by the end of October.
• Children and teens hospitalized with flu should get antiviral treatment promptly.

Limits

Testing was up to clinicians and hospitals; severity and incidence adjustments rest on past testing and care-seeking patterns; FluSurv-NET covers only part of the country; comparisons with pre-pandemic seasons may be imperfect; and differences between seasons are descriptive, not statistical tests.

Sources

Based on White EB, O'Halloran A, Sundaresan D, et al., "High Influenza Incidence and Disease Severity Among Children and Adolescents Aged <18 Years — United States, 2022–23 Season," MMWR Morbidity and Mortality Weekly Report, volume 72, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The report's summary graphic, which includes a stock photograph and a vaccination figure that does not match the text, is not reproduced.