Medically Reviewed by Poonam Sachdev on December 19, 2023
Written by Evan Starkman , Kristin MitchellBy understanding how coronavirus spreads, you can take the right steps so you don't get sick and infect others.
COVID transmission rate
Recent data from the World Health Organization (WHO) shows that since January of 2020, there have been over 103 million confirmed cases of COVID.
COVID transmission period
People seem to be most infectious about 2 days before they have symptoms and early on. If you have severe symptoms, the illness can be contagious for longer.
People infected with the virus can be contagious and can spread it even if they don't have symptoms. If you have mild COVID-19 or have no symptoms, the CDC recommends isolation through day 5 (after symptoms appear or a positive test result) and wearing a mask through day 10. Those with moderate-to-severe COVID-19 should isolate through day 10, and those who are immunocompromised through day 20.
Can pets get COVID?
Some pets have tested positive for the coronavirus. Not all of these animals had signs of illness, but some had mild symptoms. The animals may have caught the virus from close contact with humans who were infected.
Public health officials say they are still studying COVID-19 but it appears that humans can pass it to pets, although it's not as likely that pets can pass it to humans.
Experts believe the virus that causes COVID-19 spreads mainly from person to person. There are several ways this can happen:
The virus most often spreads through people who have symptoms. But it is possible to pass it on without showing any signs. Some people who don't know they've been infected and never develop symptoms can give COVID-19 to others. This is called asymptomatic spread. You can also pass it on before you notice any signs of infection and then later get symptoms, called presymptomatic spread.
Is COVID airborne?
Yes. It can get into your lungs if someone who has it breathes out and you breathe that air in. Experts are divided on how often the virus spreads through the airborne route.
How long does COVID stay in the air?
Research shows that the virus can live in the air for up to 3 hours.
Community spread
Sometimes, a person can trace how they got the virus because they know that they've been in contact with someone who's sick. In other cases, the cause is unknown. Community spread is when people in an area get the virus, including some without any known contact with someone who is sick.
Can I get infected from delivery food, packages, or groceries?
It's highly unlikely that you'll catch COVID-19 from packages, groceries, or food. If case levels are high in your community or you are at risk of infection or developing serious COVID-19 symptoms , try to keep at least 6 feet away from others in the store or have food delivered or arrange curbside pickup. If these options aren't possible, wear a face mask, too.
Wash your hands for at least 20 seconds before and after bringing things into your home. Wiping down packaging is optional. Continue to c lean surfaces that are touched often.
Since the beginning of the pandemic there have been several COVID-19 variants, including Alpha, Beta, Delta, and Omicron, with a range of dominance among the strains.
Researchers say that on average, every person who has COVID-19 will pass it on to 2 or 2.5 others. One study says that number is even higher, with one sick person infecting between 4.7 and 6.6 others.
By comparison, someone who has the flu will probably give it to an average of 1.1 to 2.3 others. But one person with measles might spread it to 12 to 18 others.
Although children tend to get infected with the coronavirus less often and have milder symptoms than adults, they can still catch and spread it. Some have become seriously ill and even died.
CDC guidelines regarding COVID-19 prevention include:
Additional guidance about extra steps you can choose to take, especially in areas known to have higher levels of COVID-19:
As you're encouraged to be vaccinated, there are currently 3 COVID-19 vaccines approved by the FDA for added protection.
The current versions of all three vaccines are geared to build immunity against the current COVID-19 variants. Recent CDC recommendations according to age group and previous vaccinations include:
Ages 5 years and older:
Ages 6 months to 4 years of age:
Those who are immunocompromised may require additional doses.
Also, if you recently had COVID-19, you can delay COVID-19 vaccination for 3 months, as you're not likely to become infected again a few weeks to a month after having COVID-19. Consider getting it sooner if:
All three vaccines are proven to be very effective in stopping the spread of COVID-19 and lowering your chance of getting very sick. The CDC states there is no preferred COVID-19 vaccine over another when more than one of these versions is available.
If you notice any allergic reactions or side effects after taking the vaccine, let your doctor know.
COVID-19 is a serious illness. It’s important to take steps to prevent the spread of the coronavirus because:
Quarantine is for people who don't have symptoms but who might have been exposed to COVID-19. The idea is to keep you from unknowingly infecting others.
Self-quarantine is usually voluntary. But the federal or state government may legally require you to do it for certain illnesses.
COVID quarantine guidelines
The CDC now recommends that instead of quarantining if you were exposed to COVID-19, you wear a high-quality mask for 10 days and get tested on day 5.
Who needs to quarantine?
You should isolate yourself if you're sick or have symptoms and don't have test results yet.
If you test positive for COVID-19 on day 5, follow the CDC guidelines for self-isolation, which include staying at home in a room that's separate from everyone else (if possible), avoiding contact with other people and pets, and wearing a face mask when you have to be near other people. If your symptoms get worse, call your doctor or hospital before you go in. Follow their instructions to get medical help.
How long does quarantine last?
Isolate yourself until there's no chance that you could spread the virus. If your test results are negative, you can end your isolation. Your doctor can also tell you when it's safe to stop.
General recommendations for self-isolation include:
Isolation is a health care term that means separating people who are contagious from people who aren't. If you have COVID-19, you'll be isolated because you may infect others. There are two types of isolation:
Medical isolation. At hospitals, health care centers, and prisons, the staff separates people who are infected from people who aren't. Staff members wear equipment like masks, gloves, and face shields to protect themselves and prevent spreading the virus.
Self-isolation. You'll be advised to self-isolate if you test positive for COVID-19 or if you have symptoms like coughing and fever but don't need to be hospitalized. Like quarantining, self-isolation is usually voluntary. But public health agencies may legally require it for certain diseases.
If you have COVID-19, regardless of whether or not you're vaccinated, you should self-isolate for 5 days.
The CDC also recommends isolation if you are sick or think you have COVID-19 but haven't taken a test. If test results are negative, you can stop isolation. If they are positive, additional recommendations include:
If you need to isolate, continue to follow current prevention guidelines.
Anyone can get COVID-19. But you have a higher chance of getting seriously ill from it if you:
If you fall into one of these categories, it's especially important for you to follow the general safety guidelines. Also, take these steps:
Get medical help right away if you have severe symptoms such as:
If it's an emergency, call 911 or head to the nearest hospital for medical attention.
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