How can I tell if my baby has RSV, flu, or COVID?

You cannot tell them apart by symptoms alone, because all three cause fever, cough, and congestion. RSV often brings wheezing and fast breathing, flu comes on abruptly with body aches, and COVID varies widely. Only a test confirms which one it is.

When should I call 911 for my baby's breathing?

Call 911 if your baby is struggling to breathe, has blue lips or face, or has pauses in breathing. Also seek urgent care for the chest sinking in with each breath, flaring nostrils, grunting, or a breathing rate over 60 breaths per minute in a newborn.

What temperature is an emergency for a young baby?

A rectal temperature of 100.4°F (38°C) or higher in a baby 3 months or younger means call the pediatrician immediately. From 3 to 6 months call for 101°F or higher, and after 6 months for 103°F or higher.

Who should get the RSV antibody nirsevimab (Beyfortus)?

All infants under 8 months entering their first RSV season, given October through March, plus some high-risk children 8 to 19 months in their second season. The dose is 50 mg under 11 lbs and 100 mg at 11 lbs or more.

Does my baby need both the maternal RSV vaccine and nirsevimab?

Most babies need only one. If the birthing parent got the RSV vaccine (Abrysvo) at 32 to 36 weeks of pregnancy and at least 14 days before delivery, the infant generally does not also need nirsevimab.

When can my baby get the flu and COVID vaccines?

Both are recommended starting at 6 months of age. For the first flu season, children 6 months through 8 years need two doses at least 4 weeks apart; after that, one dose a year.

How long does RSV last in a baby?

RSV symptoms typically peak on days 3 to 5 and last about 7 to 14 days overall. Watch for worsening breathing during the peak, which is when babies most often need medical care.

Winter safety · All ages

RSV, flu, COVID: the red flags first.

Creator: ParentFlow
Published: 2026-06-19

In winter, RSV, flu, and COVID overlap so much they cannot be told apart by symptoms alone. What matters most is recognizing the signs of trouble breathing and knowing the current ways to protect your baby.

2 min read Seasonal Safety Updated June 2026

Telling them apart

The three illnesses share fever, cough, and congestion, and only testing confirms which one a baby has. The patterns differ in emphasis.

RSV in infants leans toward the lower airways, with wheezing, grunting, fast or short breaths, flaring nostrils, and poor feeding, usually peaking on days 3 to 5. Flu tends to come on abruptly with fever, chills, and body aches. COVID has the widest range, from mild congestion to fever, body aches, and digestive symptoms, appearing 2 to 14 days after exposure.

RSV: wheezing, grunting, fast breathing, poor feeding, peaks days 3–5
Flu: sudden fever, chills, body aches, dry cough
COVID: variable, from mild congestion to fever and digestive symptoms

Red flags: when to get help now

Call your pediatrician for rapid breathing, flaring nostrils, wheezing or grunting, the chest caving in with each breath, poor feeding, signs of dehydration, or unusual drowsiness.

Call 911 right away if your baby is struggling to breathe, has blue lips or face, or has pauses in breathing. In newborns, a breathing rate above 60 breaths per minute is too fast.

Call 911: trouble breathing, blue lips or face, pauses in breathing
Chest sinking in with each breath (retractions)
Flaring nostrils, grunting, or wheezing
Not feeding, no wet diapers, no tears, unusual sleepiness

The fever rule for young babies

A rectal temperature of 100.4°F (38°C) or higher in a baby 3 months or younger calls for an immediate call to the pediatrician, even with no other symptoms, because fever at this age can signal a serious infection.

From 3 to 6 months, call for 101°F or higher. After 6 months, call for 103°F or higher. At any age, seek care for a fever above 104°F.

Current ways to protect your baby

For RSV, most babies are covered by one of two routes: the maternal RSV vaccine (Abrysvo) given at 32 to 36 weeks of pregnancy during the September to January window, or the antibody nirsevimab (Beyfortus) given to the infant. Most infants need only one of the two, not both.

Nirsevimab is given to all infants under 8 months entering their first RSV season, October through March, dosed by weight: 50 mg under 11 lbs and 100 mg at 11 lbs or more. A newer antibody, clesrovimab (Enflonsia), was FDA-approved in June 2025 as a single 105 mg dose for the 2025–26 season.

The flu vaccine is recommended every year for everyone 6 months and older; children getting it for the first time, ages 6 months through 8 years, need two doses at least 4 weeks apart. COVID vaccination is recommended from 6 months of age.

Common questions

How can I tell if my baby has RSV, flu, or COVID?: You cannot tell them apart by symptoms alone, because all three cause fever, cough, and congestion. RSV often brings wheezing and fast breathing, flu comes on abruptly with body aches, and COVID varies widely. Only a test confirms which one it is.
When should I call 911 for my baby's breathing?: Call 911 if your baby is struggling to breathe, has blue lips or face, or has pauses in breathing. Also seek urgent care for the chest sinking in with each breath, flaring nostrils, grunting, or a breathing rate over 60 breaths per minute in a newborn.
What temperature is an emergency for a young baby?: A rectal temperature of 100.4°F (38°C) or higher in a baby 3 months or younger means call the pediatrician immediately. From 3 to 6 months call for 101°F or higher, and after 6 months for 103°F or higher.
Who should get the RSV antibody nirsevimab (Beyfortus)?: All infants under 8 months entering their first RSV season, given October through March, plus some high-risk children 8 to 19 months in their second season. The dose is 50 mg under 11 lbs and 100 mg at 11 lbs or more.
Does my baby need both the maternal RSV vaccine and nirsevimab?: Most babies need only one. If the birthing parent got the RSV vaccine (Abrysvo) at 32 to 36 weeks of pregnancy and at least 14 days before delivery, the infant generally does not also need nirsevimab.
When can my baby get the flu and COVID vaccines?: Both are recommended starting at 6 months of age. For the first flu season, children 6 months through 8 years need two doses at least 4 weeks apart; after that, one dose a year.
How long does RSV last in a baby?: RSV symptoms typically peak on days 3 to 5 and last about 7 to 14 days overall. Watch for worsening breathing during the peak, which is when babies most often need medical care.

Sources & further reading

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This guide reflects current AAP, CDC, and other public-health guidance and is for educational purposes only. It does not constitute medical advice. ParentFlow is a wellness companion — not a substitute for your pediatrician. For any medical concern, contact your healthcare provider.