COVID Prevention

Medically Reviewed by Poonam Sachdev on December 19, 2023
11 min read

By 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:

  • Droplets or aerosols. This is the most common transmission. When an infected person coughs, sneezes, or talks, droplets or tiny particles called aerosols carry the virus into the air from their nose or mouth. Anyone who is within 6 feet of that person can breathe it into their lungs.
  • Surface transmission. A less common method is when you touch surfaces that someone who has the virus has coughed or sneezed on. You may touch a countertop or doorknob that's contaminated and then touch your nose, mouth, or eyes. The virus can live on surfaces like plastic and stainless steel for 2 to 3 days. To stop it, clean and disinfect all counters, knobs, and other surfaces you and your family touch several times a day.
  • Fecal-oral. Studies also suggest that virus particles can be found in infected people's poop. But experts aren't sure whether the infection can spread through contact with an infected person's stool. If that person uses the bathroom and doesn't wash their hands, they could infect things and people that they touch.

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 clean 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:

  • Stay current with COVID-19 vaccinations.
  • Get tested for COVID-19 if you have symptoms.
  • Follow recommendations for taking certain steps to prevent spreading COVID-19 if you've been exposed.
  • Move indoor activities outdoors.
  • Isolate if you suspect you have or have a confirmed case of COVID-19.
  • Stay away from others with suspected or confirmed cases. 
  • Improve the flow of air in and out of rooms, which can include opening windows, changing air filters more often, turning on fans or exhaust fans, and using HEPA (high efficiency particulate air) cleaners.
  • Get treatment if you have COVID-19 and are considered high risk of getting very sick.

Additional guidance about extra steps you can choose to take, especially in areas known to have higher levels of COVID-19:

  • Stay home from public areas, including public transportation or ride sharing if you're sick.
  • When you go out, stay away from crowded areas and try to stand at least 6 feet (about 2 arm lengths) away from people, especially if you're at a higher risk of severe illness. 
  • Wear a maskin indoor public places (2 years of age and older).

    Also, try to take certain everyday precautions:  

  • Have at least a month supply of your prescription and over-the-counter medications.
  • Wash your hands regularly with soap and water (for at least 20 seconds) or use hand sanitizer (with at least 60% alcohol).
  • Keep from touching your mouth, nose, and eyes as they are direct paths into your body for viruses.
  • When you sneeze or cough, cover your mouth and nose with a tissue or your elbow and wash your hands.
  • If you're sick, don't share kitchen, bedding, bathroom, and other household items.
  • Regularly clean areas that are touched a lot, as the virus can survive on plastic and stainless steel for up to 72 hours. 

    COVID-19 Vaccines

As you're encouraged to be vaccinated, there are currently 3 COVID-19 vaccines approved by the FDA for added protection.

  • The updated Pfizer-BioNTech COVID-19 vaccine, for ages 6 months or older
  • The updated Moderna COVID-19 vaccine, for ages 6 months or older
  • The  updated Novavax COVID-19 vaccine, for ages 12 years or older

Johnson & Johnson's Janssen vaccine, a one-dose shot for people 18 years of age and older, was previously available; however it is no longer in the U.S. 

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:

  • For ages 5-11 years old, if unvaccinated or received previous vaccination dose or doses, 1 dose of  updated Pfizer or Moderna COVID-19 vaccine is recommended

  • For ages 12 years or older who are unvaccinated, 1 dose of updated Pfizer or Moderna COVID-19 vaccines or 2 doses of updated Novavax COVID-19 vaccine

  • For ages 12 years and older who received previous vaccinations, 1 dose of updated Pfizer or Moderna  or Novavax COVID-19 vaccine

Ages 6 months to 4 years of age:

  • If unvaccinated, updated Pfizer (3 doses) or updated Moderna (2 doses) COVID-19 vaccines are recommended.

  • If previously vaccinated, the number of recommended doses depends on how many doses and which vaccine they previously received.

    Pfizer. With1 previous dose of the Pfizer vaccine, 2 doses of updated Pfizer COVID-19 vaccine are recommended. If they received 2 or more previous doses, 1 updated Pfizer COVID-19 vaccine is recommended.

    Moderna. With 1 previous dose or 2 or more previous doses, 1 updated Moderna COVID-19 vaccine is recommended (time between doses varies depending on number of previous doses).

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:

  • The current hospital admission level in your area is high. 

  • The current, most common variant is causing sickness. 

  • You're going to have close contact with a loved one and could put them at risk.

  • You're personally high risk for severe illness.

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:

  • Anyone can spread the virus. Research has found that you can spread it even if you don't have symptoms.
  • Some people are more likely than others to become seriously ill. This includes older people, people with other medical conditions, pregnant and recently pregnant people, and newborns.
  • If you get very sick from a COVID-19 infection, you may need to be hospitalized or put on a ventilator to help you breathe. In severe cases, you may die.
  • Even if you've had a COVID-19 infection, you might be able to get sick again and spread it to others.

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:

  • Wearing a properly fitted mask around other people for 10 days
  • Taking a COVID-19 test on the fifth day after exposure
  • Staying home if you develop symptoms




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 don't have symptoms or had symptoms and they are improving (i.e., fever-free for 24 hours without medication), you can stop isolation after day 5. 

  • If you have symptoms that are not improving, continue to isolate until you're without symptoms or fever-free for 24 hours without help from fever-reducing medications. 

  • If you had symptoms and your case was moderate to severe, you should isolate through day 10. For severe cases, talk to your doctor as they may also recommend testing before ending isolation.

  • Wear your mask around other people through day 10. You can remove your mask before day 10 with 2 back-to-back negative test results (48 hours apart).

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:

  • Are unvaccinated
  • Are 65 or older, especially if you live in a nursing home or other care facility
  • Have asthma or lung disease, although more research is needed on this
  • Have conditions such as cancer and blood disorders like sickle cell anemia
  • Have a weakened immune system, including conditions like HIV and sickle cell anemia or from using certain medications like prednisone for longer time periods
  • Are severely obese with a BMI over 40
  • Have type 1 or type 2 diabetes
  • Have a serious heart condition 
  • Have kidney, liver, or heart disease
  • Have brain or nervous system conditions like dementia or stroke
  • Have Down syndrome
  • Have depression or other mental health conditions

If you fall into one of these categories, it's especially important for you to follow the general safety guidelines. Also, take these steps:

  • Take all your medications as usual. Don't change your treatment plan without talking to your doctor.
  • Make sure you're up to date on vaccines.
  • Call your doctor if you have any questions about your condition or if you think you might have come into contact with the virus.
  • Don't hesitate to go to the hospital if you need emergency care for your underlying condition.

Get medical help right away if you have severe symptoms such as:

  • Trouble breathing
  • Lasting pain or pressure in your chest
  • Confusion
  • Trouble waking up or staying awake
  • Blue lips or face

If it's an emergency, call 911 or head to the nearest hospital for medical attention.