Houston deals with a rotating mix of respiratory viruses year-round, with influenza, COVID-19, and RSV as the main players. Harris County Public Health tracks all three through a weekly dashboard that monitors facility visits, school absenteeism, and test positivity rates. Beyond respiratory illness, mosquito-borne viruses like West Nile are an ongoing concern in the Houston area, especially during warmer months.
Respiratory Viruses in Harris County
The three respiratory viruses that consistently circulate through Houston are influenza (the flu), COVID-19, and RSV (respiratory syncytial virus). Harris County Public Health updates its surveillance dashboard weekly, tracking how many people visit healthcare facilities with flu-like symptoms, what percentage of tests come back positive, and how many schools report elevated absenteeism.
These viruses tend to follow seasonal patterns. Flu season in Houston typically runs from late fall through early spring, with peaks often hitting between December and February. COVID-19 has been less predictable, with surges possible at any time of year, though winter months still tend to bring higher case counts. RSV is most active in fall and winter and poses the greatest risk to young children and older adults.
If you’re trying to figure out which virus you might have, the symptoms overlap considerably. All three can cause fever, cough, fatigue, and body aches. COVID-19 is more likely to cause loss of taste or smell. RSV tends to produce heavy congestion and wheezing, particularly in children. The flu often comes on suddenly with high fever and severe body aches. A rapid test from a pharmacy or clinic is the most reliable way to tell them apart.
Stomach Bugs and Norovirus
Norovirus, the most common cause of what people call the “stomach flu,” circulates heavily in the U.S. from November through April. It spreads fast in close quarters like schools, daycares, cruise ships, and restaurants. Symptoms include sudden vomiting, diarrhea, nausea, and stomach cramps, usually lasting one to three days.
CDC data from September 2025 through January 2026 shows zero confirmed norovirus outbreaks reported to the national surveillance system from Texas during that window. That doesn’t mean norovirus isn’t present. Most cases go unreported because people recover at home without seeing a doctor. But it does suggest Houston hasn’t experienced a large, documented cluster recently. The biggest risk factor for norovirus is contact with someone who’s actively sick, so frequent handwashing with soap and water (not just hand sanitizer, which is less effective against norovirus) is the best defense.
Mosquito-Borne Illness
Houston’s warm, humid climate makes it a hotspot for mosquito-borne diseases, and West Nile virus is the primary threat. In January 2026, Harris County Public Health confirmed the first positive mosquito samples of the year in ZIP codes 77041 and 77032, both in north and northwestern Harris County. Finding positive samples this early in the year is notable, since mosquito activity typically ramps up in spring and summer.
For context, the summer of 2024 was a particularly active West Nile season. Harris County identified 520 positive mosquito samples across more than half of its operational monitoring areas, and seven residents in unincorporated Harris County were diagnosed with West Nile virus infections. Two additional cases of travel-related dengue were also reported that summer.
Most people infected with West Nile never develop symptoms. About one in five gets a fever, headache, and body aches that resolve on their own. Roughly 1 in 150 infections leads to serious neurological illness. The standard prevention advice applies: use EPA-registered insect repellent, wear long sleeves during dawn and dusk when mosquitoes are most active, and eliminate standing water around your home where mosquitoes breed.
How to Check Current Levels
If you want real-time data rather than a snapshot, Harris County Public Health maintains an interactive respiratory virus dashboard at publichealth.harriscountytx.gov. It breaks down flu-like illness by facility visits, school absenteeism rates, and the percentage of positive flu, RSV, and COVID-19 tests. The dashboard updates weekly.
The City of Houston also operates a wastewater monitoring dashboard that tracks viral particles in the sewage system. Wastewater surveillance picks up infections across the population, including people who never get tested, making it one of the most accurate ways to gauge how much virus is actually circulating. You can check trends at covidwwtp.spatialstudieslab.org.
Free Testing and Vaccination
Harris County Public Health offers COVID-19 vaccines at no charge regardless of your insurance status. You can sign up for testing through their website as well. The Houston Health Department runs similar programs. Updated COVID-19 vaccines targeting recent variants, annual flu shots, and RSV vaccines (approved for adults 60 and older and for pregnant individuals to protect newborns) are all available through these programs and most local pharmacies.
If you’re feeling sick and unsure what you have, many pharmacies now offer combination rapid tests that check for both flu and COVID-19 simultaneously. These cost around $15 to $25 over the counter and give results in about 15 minutes, which can help you decide whether antiviral treatment might be worth discussing with a provider, since both flu and COVID-19 antivirals work best when started within the first day or two of symptoms.