COVID-19

How COVID-19 spreads

SARS-CoV-2 spreads mainly when an infected person breathes, talks, coughs or sneezes, releasing droplets and smaller aerosol particles. Spread is most likely indoors, at close range and in poorly ventilated spaces. People can spread the virus a day or two before symptoms start and are most contagious in the first few days of illness. Some people never develop symptoms but can still spread it.

Symptoms

Symptoms usually start 2 to 5 days after exposure and range from none to severe:

• sore throat, often an early symptom
• runny or stuffy nose
• cough
• fever or chills
• tiredness and body aches
• headache
• loss of smell or taste, less common with recent variants than early in the pandemic
• nausea, vomiting or diarrhea
• shortness of breath, which is a warning sign

Older adults may present with confusion, falls or loss of appetite rather than typical symptoms.

How long does COVID-19 last?

Most mild cases improve within 7 to 10 days. Cough and tiredness may linger for a few weeks. Severe illness can last weeks and require hospital care.

COVID-19 vs flu vs cold

Because the symptoms overlap, testing is the only reliable way to tell COVID-19 from flu. Combination home tests for both are available.

Who is at higher risk of severe illness

• adults 65 and older, with risk rising with age
• people with weakened immune systems, including cancer treatment and organ transplants
• chronic lung, heart, kidney or liver disease
• diabetes and obesity
• pregnancy
• people who are not up to date with vaccination

Testing

• Home antigen tests: quick and convenient. Test when symptoms start. If negative, test again 48 hours later, as early antigen tests can miss infection.
• PCR tests: more sensitive, done at clinics or pharmacies.

Staying home and preventing spread

Current CDC respiratory virus guidance:

• Stay home and away from others while you are sick.
• You can return to normal activities when your symptoms are getting better overall and you have had no fever for at least 24 hours without fever-reducing medicine.
• For the next 5 days, take extra precautions: wear a well-fitting mask around others, improve ventilation, keep your distance, and wash your hands often.
• Take extra care around people at higher risk.

Treatment

Home care for mild illness

• rest and fluids
• acetaminophen (paracetamol) or ibuprofen for fever and aches, at the label dose. Do not give aspirin to children or teenagers.
• honey for cough in adults and children over 1 year
• throat lozenges and saline nasal sprays

Antiviral treatment

For people at higher risk of severe illness, antivirals reduce the chance of hospitalization and death, even if symptoms are mild:

• Nirmatrelvir with ritonavir (Paxlovid): pills taken for 5 days, started within 5 days of symptoms. It interacts with many common medicines, so a doctor or pharmacist must check your medication list.
• Remdesivir: intravenous treatment over 3 days.
• Molnupiravir: an alternative pill when others are not suitable. Not used in pregnancy.

Contact your doctor, a telehealth service or pharmacist as soon as you test positive if you are at higher risk.

Hospital treatment

Severe COVID-19 is treated with oxygen, dexamethasone (a steroid), remdesivir, immune-modulating medicines in some cases, blood thinners to prevent clots, and breathing support.

Complications

• pneumonia and acute respiratory distress syndrome
• blood clots, including pulmonary embolism
• heart inflammation (myocarditis)
• worsening of chronic conditions
• MIS-C, a rare inflammatory syndrome in children weeks after infection
• long COVID

Long COVID

Long COVID (post-COVID condition) is a range of symptoms lasting at least 3 months after infection, which can occur even after mild illness. Common symptoms include:

• fatigue that worsens after physical or mental effort (post-exertional malaise)
• brain fog and difficulty concentrating
• breathlessness and cough
• a fast heart rate on standing, sometimes meeting criteria for POTS
• sleep problems, headaches, joint and muscle pain
• changes in smell or taste
• anxiety and low mood

There is no single test or cure. Management focuses on symptoms, pacing activity to avoid crashes, treating specific problems such as POTS, and rehabilitation. Vaccination reduces the risk of long COVID. Many people improve gradually over months.

Prevention

• Vaccination: stay up to date with the COVID-19 vaccine recommended for your age and health. Updated vaccines are released regularly to match circulating variants.
• Improve ventilation indoors, and gather outdoors when possible.
• Stay home when sick, and test if you have symptoms.
• Masks: a well-fitting high-filtration mask in crowded indoor spaces helps protect high-risk people.
• Hand washing.

Frequently asked questions

What are the first symptoms of COVID-19?

A sore or scratchy throat, congestion, tiredness and a headache are often the first symptoms with current variants, followed by cough, fever and aches. Some people lose their sense of smell or taste. Symptoms usually begin 2 to 5 days after exposure.

How long is COVID-19 contagious?

People are most contagious from about a day before symptoms start until a few days after. Current CDC guidance is to stay home until symptoms are improving and you have had no fever for 24 hours without medicine, then take extra precautions such as masking for 5 more days.

Who should take Paxlovid?

Nirmatrelvir with ritonavir is recommended for people at higher risk of severe COVID-19, such as adults over 65 and people with weakened immunity or chronic conditions, started within 5 days of symptoms. It interacts with many medicines, so a doctor or pharmacist must review your medicines first.

Can you get COVID-19 more than once?

Yes. Immunity from infection and vaccination wanes over time, and new variants can partly evade it. Reinfections are common, although they tend to be milder in people with existing immunity. Staying up to date with vaccines reduces the risk of severe illness.

What is long COVID?

Long COVID is a set of symptoms, such as fatigue, brain fog, breathlessness and a racing heart, that last 3 months or more after COVID-19. It can follow even mild infections. Treatment focuses on symptoms, pacing activity and rehabilitation, and many people improve over time.