Respiratory viruses are climbing in U.S. schools

Early-January 2026 media reports and surveillance data indicate that multiple respiratory viruses are increasing as winter approaches. Health professionals note that children and schools are the first places where rising circulation becomes obvious. The viruses causing most concern include parainfluenza, rhinovirus/enterovirus, influenza A, and respiratory syncytial virus (RSV).

Below is a summary of recent surveillance reports and expert comments on these viruses.

Influenza A

• UK Health Security Agency (UKHSA) surveillance report for week 48 (ending 30 Nov 2025) found that influenza test positivity in England increased to 17.1%, up from 11.6% the previous week; positivity was highest (43.6%) among children aged 5–14 years (gov.uk).
• The same report notes that UK hospitals tested 4,154 specimens and found 529 positive influenza samples; 443 were influenza A (including 81 H3N2 and 4 H1N1) and positivity increased to 12.7% (gov.uk).
• Seattle Children's Hospital reported on 3 Dec 2025 that influenza-like activity nationally remained below epidemic thresholds but hospital activity was entering "the steep part of the curve," suggesting a rapid rise is imminent (seattlechildrens.org). They warned that a new H3N2 subclade K virus linked to early severe seasons in the UK, Canada and Japan could lead to a higher-than-usual surge (seattlechildrens.org).
• Cleveland Clinic's respiratory pathogen report (updated 24 Nov 2025) noted that influenza A positivity was around 3%, with the H3N2 subclade K circulating in Northeast Ohio (clevelandcliniclabs.com).
• New Jersey's Respiratory Illness Surveillance Report for week 48 (ending 29 Nov 2025) stated that emergency department visits resulting in admission increased for influenza; test positivity rose for influenza and outbreaks in schools were mainly due to influenza (nj.gov).
• Public Health Madison & Dane County (Wisconsin) reported on 4 Dec 2025 that flu levels were currently low but starting to increase, and encouraged vaccination (publichealthmdc.com).
  Sources: UKHSA, Seattle Children's, Cleveland Clinic, NJ DOH, PHMDC

RSV (Respiratory Syncytial Virus)

• UKHSA's week 48 data show RSV positivity increasing to 10.5% compared with 9.6% in the previous week; positivity was highest (39.5%) among children aged 0–4 years (gov.uk).
• Seattle Children's reported that RSV positives were at moderate levels and continuing to climb, and they expected a significant surge over the next few weeks (seattlechildrens.org).
• Cleveland Clinic observed upticks in RSV positivity (~1% across all ages and ~7% among children <5 years) as of 24 Nov 2025 (clevelandcliniclabs.com).
• The New Jersey report noted that emergency department admissions for RSV increased and test positivity rose for RSV (nj.gov).
• Madison & Dane County health officials similarly reported low RSV levels but signs of a slight increase (publichealthmdc.com).
  Sources: UKHSA, Seattle Children's, Cleveland Clinic, NJ DOH, PHMDC

Rhinovirus/Enterovirus

• UKHSA data show rhinovirus positivity decreasing to 12.8%, yet it remained highest (27.8%) among children under 5 years old (gov.uk).
• Seattle Children's found rhinovirus/enterovirus to be the most common positive in their testing and noted that this category includes multiple virus strains (seattlechildrens.org).
• Cleveland Clinic reported that rhinovirus/enterovirus positivity remained elevated at 17%, even as other viruses increased (clevelandcliniclabs.com).
• HealthTrackRx's respiratory trend report (week ending 30 Nov 2025) shows that rhinovirus/enterovirus contributed the largest share of positives (26.2%) but was trending downward after fall peaks (healthtrackrx.com).
• Madison & Dane County noted that positive lab tests for rhinovirus and enterovirus remained high (publichealthmdc.com).
• New Jersey's surveillance report stated that test positivity remained elevated for rhinovirus/enterovirus (nj.gov).
  Sources: UKHSA, Seattle Children's, Cleveland Clinic, HealthTrackRx, PHMDC, NJ DOH

Parainfluenza

• UKHSA reported that parainfluenza positivity increased slightly to 3%, with the highest positivity (4.9%) in children aged 5–14 years (gov.uk).
• Seattle Children's said parainfluenza was having its usual fall increase, leading to more cases of croup (seattlechildrens.org).
• HealthTrackRx noted that parainfluenza positivity decreased from 8.1% to 6.7% but remained elevated compared with baseline (healthtrackrx.com).
• The New Jersey report observed that test positivity increased for human metapneumovirus but did not highlight parainfluenza; however, it noted that positivity for parainfluenza viruses remained elevated for rhinovirus/enterovirus, implying continuing activity (nj.gov).
• The U.S. Centers for Disease Control and Prevention (CDC) notes that human parainfluenza virus types 1 & 2 peak in the fall, HPIV-3 peaks in the spring, and HPIV-4 occurs in the fall/winter (cdc.gov).
  Sources: UKHSA, Seattle Children's, HealthTrackRx, CDC

Background on Seasonality & Risk

• CDC explains that rhinoviruses spread year-round but peak in the spring and late summer/fall (cdc.gov), and that HPIV-1 & 2 peak in the fall, HPIV-3 peaks in spring, and HPIV-4 occurs in fall/winter (cdc.gov).
• Parainfluenza viruses often cause croup, particularly in young children (cdc.gov).
• Rhinovirus/enterovirus can cause severe illness in individuals with asthma or weakened immunity (cdc.gov).
• Infants, young children and people with weakened immune systems are at higher risk for severe infection with HPIVs (cdc.gov).
  Source: CDC

Why schools matter:

Schools are often the first setting where rising virus activity becomes obvious. New Jersey's surveillance report noted that respiratory outbreaks in schools are primarily due to influenza, and several jurisdictions report high rhinovirus positivity in younger children.

Early signals in schools are therefore a critical alert for communities to prepare.

What we can do to mitigate the spread

• Get vaccinated – updated flu and RSV vaccines are available for many age groups. Seattle Children's emphasizes that early vaccination is key as the dominant H3N2 strain may lead to a more severe season, and New Jersey & Wisconsin authorities encourage vaccination as cases rise.
• Practice good hygiene and stay home when sick – handwashing, covering coughs and improving indoor air quality reduce spread. CDC notes that HPIV and rhinovirus can spread easily and cause severe illness in vulnerable groups.
• Be aware of symptoms and seek care when necessary – RSV and parainfluenza can cause croup or bronchiolitis in young children; influenza can cause high fever and muscle pain. Early evaluation is important for infants, pregnant people and those with chronic conditions.

By watching the signals coming from our schools and using the tools we have (vaccination, masks when sick, staying home), we can reduce transmission and keep our communities healthier this winter.