Fall is here, and with it comes an increase in respiratory illnesses like influenza, COVID-19, RSV and the common cold. Although these illnesses circulate year-round, they tend to spread more easily as we spend more time indoors. Because many share similar symptoms, knowing what sets them apart can help you decide when to stay home, when to seek testing or treatment and how to protect yourself and those around you.

Tine Vindenes, MD, MPH, division chief of Infectious Disease and Geographic Medicine at Tufts Medical Center and Assistant Professor of Medicine, Tufts University School of Medicine, shares what to know heading into respiratory illness season.

What to know this fall

• Don’t forget the basics. Wash your hands regularly and stay home from work or school when you’re sick.
• Flu and COVID-19 vaccines have been updated for the 2026–27 season to better match the strains expected to circulate this year.
• The nasal spray flu vaccine is still available. For eligible people ages 2 through 49, FluMist can be self-administered or given by a caregiver, including through an at-home option.
• A new mRNA flu vaccine is available for the first time. mRNA vaccines use messenger RNA to give cells instructions that help the body develop an immune response. The new flu vaccine is approved for adults ages 50 and older.

Not every cough, congestion or sore throat means the same thing. And when you’re not feeling well, it can be hard to know what you’re dealing with or whether you need to see a doctor. Here’s what to know about the most common respiratory illnesses, how to tell them apart and when you may need testing or treatment.

The Common Cold

What is it?

A respiratory infection of your nose, sinuses and throat. Colds are caused by viruses that spread from person to person. You can catch a cold by breathing in air with the virus after someone sneezes or coughs. You can also become sick after touching a surface with virus droplets and then touching your eyes, nose or mouth.

Symptoms

Colds have a range of symptoms that include:

• Runny nose
• Sneezing
• Headache
• Sore throat
• Cough
• Congestion

Symptom duration varies. Some colds last 1–3 days, and others take longer to resolve. It isn't unusual to have a prolonged cough or fatigue after a cold, and it doesn't mean you're still contagious. You're most contagious the first three days when symptoms appear.

When should you get tested or treated?

There’s no specific treatment for the common cold, so testing usually isn’t necessary. Rest, plenty of fluids and over-the-counter medications can help you feel more comfortable while you recover. If your symptoms get worse or don’t improve within two weeks, check in with your doctor.

Vaccination

There's no vaccine for the common cold.

Influenza (aka “the flu”)

What is it?

Millions of people in the U.S. get influenza each year. Influenza, or the “flu,” is a contagious respiratory illness caused by the influenza virus. Like the common cold, you can catch it by breathing in the virus after someone sneezes or coughs. You can also become sick after touching a surface with virus droplets and then touching your eyes, nose or mouth.

Symptoms

Flu symptoms usually come on suddenly. Generally, people feel feverish and achy for 3–5 days; other symptoms, like coughing, can last up to 6 weeks. People are the most contagious during the first three days of getting the flu. If you have the flu, you may have some or all of the following symptoms:

• Fever/chills
• Cough
• Sore throat
• Runny/stuffy nose
• Muscle or body aches
• Headaches
• Fatigue
• Vomiting/diarrhea (this is more common in children)

When should you get tested or treated?

Most people get better from the flu without getting medical help or taking medicine. Testing is only recommended for people who are at the highest risk for complications of the flu. Those people should also get treatment.

Talk to your doctor about getting an antiviral prescription. You should start taking it within 72 hours of noticing the symptoms, or sooner, to get the best results.

Vaccination

“We recommend everyone six months and older get a flu vaccine every season,” says Dr. Vindenes. “Unless there is contraindication to vaccination. The best time to get the vaccine is in October, but it is still effective and recommended throughout the respiratory viral season.” It’s especially important for people at higher risk of serious complications from the flu to get vaccinated.

Anyone can get the flu, but some people are at greater risk of developing serious complications. This includes adults 65 and older, young children under 5, pregnant people and those with chronic health conditions such as diabetes, heart disease or asthma.

Several flu vaccine options are available. In addition to the standard injectable vaccine, a live, weakened-virus nasal spray vaccine is available for people ages 2 through 49. It can be self-administered or given by a caregiver, though it isn't recommended for people with certain health conditions. A new mRNA flu vaccine will also be available this year for adults ages 50 and older.

Respiratory syncytial virus (RSV)

What is it?

RSV is an infection of the lungs and respiratory tract that causes cold-like symptoms. Anyone can get RSV, but severe disease-causing hospitalization is more common in infants and toddlers as well as people over 75 years of age.

Symptoms

Most people with RSV will have mild symptoms. Common symptoms include the following:

• Runny nose
• Decrease in appetite
• Coughing
• Sneezing
• Fever
• Wheezing

RSV can lead to severe infection in infants and premature infants, older adults, people with heart and lung disease, people with weakened immune systems and people who live in nursing homes or long-term care facilities. In severe cases, symptoms can progress to cause pneumonia or bronchiolitis.

When should you get tested or treated?

If your child is very sick, you can get RSV testing at your child’s pediatrician office. If your child is very sick and needs to be tested but an appointment with a pediatrician is not available, this can be done at an urgent care center or the emergency room. Testing is rarely recommended in adults and older healthy children because no specific treatment is available. Like the common cold, over-the-counter medications can be used to treat symptoms.

Vaccination

A single dose of the RSV vaccine is recommended for all adults over the age of 75; adults 50 to 74 years at higher risk for severe RSV disease including chronic lung disease and cardiovascular disease and pregnant females between 32 and 36 weeks from September to January to prevent RSV in their baby.

Newborns whose mothers didn't receive the vaccine during pregnancy, and some high-risk older babies, should receive an injection of an antibody against RSV.

COVID-19

What is it?

COVID-19 is a contagious disease caused by the SARS-CoV-2 virus. Like other illnesses that affect the respiratory system, it is spread through droplets that are exhaled or expelled by an infected person and enter another person’s body by landing in their eyes, nose or mouth. COVID-19 can be spread from someone with minimal or no symptoms.

Symptoms

People most at risk for severe symptoms include adults aged 65 or older, people with certain chronic medical conditions such as lung disease or heart disease, those who are pregnant and those who have compromised immune systems.

COVID-19 symptoms appear 2–14 days after exposure and can range from mild to severe and include the following:

• Fever or chills
• Cough
• Shortness of breath or difficulty breathing
• Sore throat
• Congestion/runny nose
• Fatigue
• Muscle or body aches
• Headache
• Nausea or vomiting
• Diarrhea

When should you get tested or treated?

It’s especially important for those at high risk for severe COVID-19, who are over the age of 65 or with underlying medical conditions that increase their chances of getting extremely sick, to get tested to be started on antiviral treatment, which is more effective the earlier it is given.

There are several types of tests, including ones that can be performed at home.

Vaccination

The COVID-19 vaccine has been updated again this year to better target circulating strains. Guidelines for who should receive the 2026-2027 COVID-19 vaccine Children ages 6-23 months

• Healthy children 2-18 years of age who have never received a COVID-19 vaccine.
• Children who are residents of long-term care facilities
• Adults 19-65 and ‌‌adults 65 years of age and older should receive two doses of the 2026-2027 COVID-19 vaccine, with the second dose administered 6 months after the first
• People with immunocompromised conditions 
• Children and adults with medical conditions associated with a higher risk for severe COVID-19
• People who are pregnant, contemplating pregnancy or have recently been pregnant or who are lactating.
• Healthcare workers
• Healthy children and adolescents 2-18 may also receive a dose of the 2026-2027 COVID-19 vaccine

Guidelines may differ between states. Speak to your doctor or pharmacist about the COVID-19 vaccine

Pertussis

What is it?

Pertussis, also known as whooping cough, is a highly contagious respiratory illness caused by a bacterial infection that spreads easily from person to person through coughing or sneezing. In Massachusetts, pertussis is most common among children over 10 years old whose protection from their childhood vaccines has lessened over time.

Symptoms

People can spread the bacteria from the start of symptoms and are most contagious for three weeks after the cough begins. Pertussis is similar to a cold early on, but people can develop uncontrolled coughing fits lasting up to 10 weeks. Babies and children who aren't fully vaccinated are more likely to have serious complications.

Pertussis symptoms appear 7 to 10 days after infection and include the following:

• Mild fever
• Runny nose
• Cough
• Red, watery eyes
• Sore throat
• Nasal congestion

Symptoms worsen 1 to 2 weeks after the first symptoms appear and may include:

• Vomiting during or after coughing fits
• Coughing fits that cause a red or blue face and/or a whooping sound
• Extreme fatigue
• Difficulty breathing
• Rib fracture

Infants may struggle to breathe or stop breathing, a symptom called apnea and may not develop a cough at all. Babies can have the following symptoms:

• Apnea
• Pneumonia
• Convulsions
• Encephalopathy (brain disease)

When should you get tested or treated?

Pertussis can be hard to diagnose because it mimics other common respiratory illnesses that generally don't require testing. When cough is severe and prolonged, testing can help pinpoint the cause of your symptoms and avoid more invasive tests. Once the diagnosis is made, antibiotics can be used to decrease the period of contagiousness, but they don't improve symptoms. Close contacts will also be treated with antibiotics to prevent infection.

Vaccination

Vaccines are available for infants, children, adolescents and pregnant women early in the third trimester (between weeks 27 and 36). Like most vaccines, vaccination doesn’t reduce the risk of infection to zero but can help prevent severe disease. A booster vaccine for pertussis is recommended every 10 years for adults 65 years and older. A booster with pertussis (Tdap) should be given to adults 18-64 years if they haven’t already had Tdap previously.

How to protect yourself and others

Getting sick is never fun, but a few simple steps can help you feel better, protect the people around you and reduce your risk of getting sick again. Wash your hands regularly, stay home when you’re sick, avoid close contact with people who are sick, cover your coughs and sneezes and stay up to date on recommended vaccines to protect against serious illness.

Tufts Medicine’s Symptom Checker can help you find out what's causing your symptoms and help you get care.

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