Public Health

How Long Is Coronavirus Contagious?

Mira Research Team09 Feb 2021

Quick Digest: How Long am I Contagious With Coronavirus? 

  • COVID-19 is spread through aerosol droplets when we breathe, speak or sing. The virus can be transmitted even if someone is asymptomatic.
  • If you believe you have COVID-19 or had an exposure, you should immediately isolate yourself from others and seek out a PCR or rapid antigen test. A membership with Mira can help you get access to a free at-home PCR test.
  • If you had COVID-19, you can be around others if 10 days have passed since your first symptoms, symptoms are improving AND you have had no fever for at least 24 hours without taking fever-reducing medications.

Dr. Jesse Pelletier (MD, FACS) helped answer some questions for our article. Dr. Pelletier is a practicing eye surgeon and Head of Infection Control at two medical institutions in Miami. He is also the President and co-founder of Halodine, a nasal spray product used in the fight against Covid-19. 

Coronavirus Spreads Through Respiratory Droplets 

According to Dr. Jesse Pelletier (MD, FACS), the SARS-CoV-2 virus initially infects, replicates, and spreads from the nose and the mouth. Whenever one breathes, speaks, coughs, or sneezes we are producing turbulent airflow in the upper respiratory mucosa. 

This airflow, through the production of a shearing force, creates microscopic respiratory droplets and aerosols that are emitted from the nose and mouth into the surrounding air. When you are infected, viral particles are captured within these droplets and aerosols. 

Depending upon their size, droplets will often follow a ballistic trajectory subject to gravity and fall to the ground within a few seconds. Aerosols, often 10 microns or less, are commonly caught in air currents and may float or drift for hours. 

When an infected person emits these particles, they may land in the nose or mouth of infected persons. They may also be inhaled by an uninfected person into the deeper respiratory tree. Spread can also occur through contact with objects that harbor the virus. 

Coronavirus is Highly Contagious and Spreads Easily 

Coronavirus is considered a highly contagious disease and appears to spread more easily than other viruses, such as the flu. In addition, asymptomatic people can spread COVID-19 to others. 

Researchers at Harvard’s School of Public Health explain how contagious COVID-19 may be. Public health experts use R0 to signify how many people someone with a specific virus will typically infect. 

For context, the R0 from the 1918 flu was estimated to be between 1.4 and 2.8. Researchers are now predicting the R0 for COVID-19 might be 5 or 6. This means that in some regions of the United States, each person with COVID-19 can infect 5-6 others.

In addition, a new strain of COVID-19 was discovered in the U.K. and spread to the U.S. and other countries. This curated strain is believed to be 70% more transmissible than the first strain of COVID-19. 

For these reasons, it is very important to continue to wear cloth face coverings or face masks in public, avoid large gatherings, and practice social distancing. Most importantly, if you are feeling sick or have had close contact with someone who is positive for COVID-19 make sure to self-isolate. 

Coronavirus May Be Most Contagious During The First 5 Days of Illness

According to Harvard Medical School, people can spread COVID-19 48-72 hours before showing symptoms. A recent study in The Lancet suggests that people are most contagious during the first 5 days of illness. All individuals in the study were no longer shedding live virus after 9 days of illness.

These results indicate that it is highly important to wear masks, social distance, and quarantine immediately if you believe you were exposed to someone with COVID-19, as you can spread the virus before you even show symptoms. 


COVID-19 May Be More Contagious In The Winter Months 

Most viruses, such as the flu, are more contagious in the winter for a few reasons: 

  1. We spend more time indoors in close proximity to others
  2. We have less vitamin D intake
  3. Cold air may be more conducive to the spread of viruses

In addition, this winter we will not only be dealing with coronavirus but the common cold and flu as well. Read our article for more information on differentiating between the flu, a cold, and coronavirus. 

Below We Outline When You Can Safely Interact With Others After Having COVID-19

In general, you should self isolate for 10 days if you were positive for COVID-19 and 14 days if you had close contact with someone who had COVID-19. There is a 14 incubation period for the virus, meaning you can be exposed to the virus and begin to show symptoms up to 14 days later. 

Below we outline guidance for people who fall into the following categories: 

If you think or know you had COVID-19 and experienced symptoms

If you experienced some of the symptoms of COVID-19, such as shortness of breath, fever, loss of taste, sore throat, or fatigue, the CDC recommends that you follow these guidelines. You can safely see others when you have met all three of the following criteria: 

  1. 10 days have passed since the onset of your first symptoms
  2. 24 hours have passed without having a fever (without using fever medication, such as Ibuprofen)
  3. Your symptoms are generally improving (other than a loss of taste or smell, which can persist for an extended period of time)

In order to protect your family, friends, and community members, you should follow these guidelines if you have symptoms - even if your COVID-19 test came back negative. 

If you tested positive for COVID-19 but didn’t have symptoms

If you tested positive for COVID-19, but you are not experiencing symptoms, you should follow these guidelines: 

  1. You may resume seeing people after 10 days have passed since your first positive test result
  2. If you begin to experience symptoms, follow the guidelines in the section above, meaning that you need to wait 10 days since your symptoms first appear before seeing anyone

If you were very ill with COVID-19 or have a severely weakened immune system (immunocompromised) due to a health condition or medication

If you were very ill with COVID-19, you may need to self-isolate for up to 20 days to ensure that you can safely interact with others. In these situations, it is best to reach out to a health care provider or your local health department to assist in this decision-making.  

If you do not regularly see a health care provider, a membership with Mira may be able to help. For only $25/month, you will get discounted rates for urgent care visits, laboratory testing, and prescriptions. If you get a membership with Mira, you can make an appointment with a physician at an urgent care facility to talks about your safest plan after having COVID-19. 

If you’ve been around a person with COVID-19

If you were exposed to someone who has tested positive for COVID-19, it is important that you self-isolate for 14 days after your most recent exposure. Even if you get a negative test result, it is best to stay home for two weeks if possible. 

The following people are exempt from this recommendation: those who had COVID-19 in the past three months, fully recovered, and are not experiencing any symptoms. 

If you are a healthcare professional

Healthcare professionals should follow all of the aforementioned guidelines if symptomatic, asymptomatic, or exposed to COVID-19. 

You May Continue To Test Positive For COVID-19 After Recovery

Even if you recovered from COVID-19, you may continue to test positive on a PCR test for 3 months. As long as you are not showing symptoms, experts believe that a positive test is a result of viral RNA shedding rather than an active infection. 

As long as you meet the criteria outlined above, the CDC reports that they do not believe you will be contagious.


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