New Yorkers preparing for the 2026-27 flu season have an updated vaccine available, but a Rochester infectious disease specialist cautions that vaccination and home testing serve different purposes: One helps protect against illness, while the other can help guide care after symptoms begin.
In a University of Rochester Medicine guide, Dr. Angela Branche explains why fall vaccination remains important, why a negative home test cannot rule out flu and why people at higher risk should contact a health care provider promptly when they become sick.
The guidance comes as the New York State and New York City health departments endorsed respiratory virus immunization recommendations Sept. 10. The recommendations cover flu, COVID-19 and respiratory syncytial virus, or RSV, ahead of the fall and winter respiratory illness season.
For Finger Lakes residents, the immediate questions are practical: When should they get vaccinated, what can a home test tell them and which symptoms require medical attention?
What changed in this season’s vaccine
All three virus components in the 2026-27 U.S. flu vaccine were updated from the previous season, according to the Centers for Disease Control and Prevention’s season overview.
The vaccine targets two influenza A viruses — H1N1 and H3N2 — and one influenza B virus from the Victoria lineage. The H3N2 update addresses the subclade K viruses that spread widely during the 2025-26 season.
Those changes reflect efforts to match the vaccine to viruses expected to circulate. They do not establish how severe the coming season will be or guarantee protection against every infection.
Rochester Medicine says it is too early to know which viruses will dominate or how severe the season will become. Activity can differ between communities.
Influenza A and B both cause seasonal flu. Influenza A includes subtypes such as H3N2; either type can cause serious illness.
September and October are the main vaccination window
Annual flu vaccination is recommended for everyone 6 months and older, with rare exceptions. For most people who need one dose, September and October are generally the preferred months, according to CDC vaccination guidance.
Vaccination can still be useful later in the season. It takes about two weeks for the body to develop protective antibodies.
Some children need two doses, separated by at least four weeks. Parents should ask their child’s clinician which schedule applies.
For adults 65 and older, CDC preferentially recommends a high-dose, recombinant or adjuvanted flu vaccine. A clinician or pharmacist can help identify an appropriate option.
A nasal spray vaccine is approved for ages 2 through 49, but it is unsuitable for some people, including those who are pregnant or immunocompromised.
Vaccination does not eliminate the possibility of catching flu. Branche emphasizes that it can still reduce the risk of severe illness, hospitalization and complications.
Flu vaccines cannot cause influenza. Rochester Medicine notes that mild effects such as soreness, fatigue or a low-grade fever can occur after vaccination.
A negative home test does not rule out flu
Home flu tests can provide useful information when someone develops respiratory symptoms, but the result needs to be considered alongside symptoms and medical risk.
The CDC’s flu testing guidance explains that rapid tests vary in their ability to detect influenza. A false negative occurs when a person has flu but the test does not detect it.
A clinician may diagnose flu despite a negative rapid test, based on symptoms and clinical judgment. People should follow the instructions for their particular test, including its requirements for collecting a sample and interpreting results.
Branche advises contacting a health care provider when symptoms are severe or worsening, even after a negative result.
Flu, COVID-19 and RSV can produce overlapping symptoms. It is also possible to have flu and COVID-19 at the same time, so a positive result for one does not necessarily exclude the other.
Rochester Medicine says its virtual urgent care clinicians can use home test results to help assess next steps. Emergency symptoms, however, require immediate medical care.
Early treatment matters, especially for higher-risk patients
Prescription antiviral medications, including oseltamivir, sold under the brand name Tamiflu, work best when started early — ideally within the first 48 hours of symptoms.
That window should not be interpreted as a reason to give up on seeking care after two days.
The CDC recommends prompt antiviral treatment for people who are hospitalized, have severe or worsening illness, or are at higher risk of flu complications. Clinicians should not wait for laboratory confirmation before starting treatment in those priority groups.
Treatment can still benefit some patients with severe illness when begun after 48 hours.
People at higher risk include older adults, pregnant people, young children and those with certain chronic conditions or weakened immune systems. Branche specifically advises higher-risk patients to seek care even when symptoms began more than two days earlier.
Most otherwise healthy people with mild flu do not need antiviral medication, according to the CDC’s treatment guidance. A clinician can determine whether treatment is appropriate.
Know the symptoms and emergency warning signs
Flu commonly causes fever or chills, cough, body aches, headache and fatigue. Vomiting and diarrhea can occur, particularly in children. Not everyone with flu has a fever.
The CDC identifies emergency warning signs that require medical care right away, including difficulty breathing, persistent chest pain or pressure, confusion, seizures and signs of dehydration.
In children, warning signs include fast or difficult breathing, bluish lips or face, ribs pulling inward with each breath, lack of alertness and no urine for eight hours. Any fever in a child younger than 12 weeks requires immediate medical attention.
A fever or cough that improves and then returns or worsens is another warning sign. The CDC advises seeking care for other severe or concerning symptoms as well.
Flu protection is part of a broader fall health plan
Rochester Medicine advises discussing flu, COVID-19 and RSV immunizations with a health care provider to determine which are appropriate and when to receive them. More than one vaccine may be given at the same visit, depending on the person’s circumstances.
For infants, protection against severe RSV can come through vaccination during pregnancy or an antibody given to the baby. Prenatal and pediatric clinicians can explain which option applies.
Influenza viruses continually change, which is why vaccines are reviewed and updated each year. Branche says Rochester researchers and scientists elsewhere are studying ways to provide broader, longer-lasting protection.
For this season, residents can ask their clinician or pharmacist about the updated flu vaccine and make an early plan for contacting a provider if symptoms develop — especially when someone in the household is at higher risk.
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