COVID-19Common question

Symptoms may appear 2 to 14 days after exposure to the virus.

When is someone with COVID-19 infectious?

The onset and duration of viral shedding and the period of infectiousness for COVID-19 are not yet known with certainty. Based on current evidence, scientists believe that persons with mild to moderate COVID-19 may shed replication-competent SARS-CoV-2 for up to 10 days following symptom onset, while a small fraction of persons with severe COVID-19, including immunocompromised persons, may shed replication-competent virus for up to 20 days. It is possible that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset, similar to infections with MERS-CoV and SARS-CoV. However, detection of viral RNA does not necessarily mean that infectious virus is present. Based on existing literature, the incubation period (the time from exposure to development of symptoms) of SARS-CoV-2 and other coronaviruses (e.g., MERS-CoV, SARS-CoV) ranges from 2–14 days.

How long do you need to stay home after coming into close contact with someone who has COVID-19?

Anyone who has had close contact with someone with COVID-19 should stay home for 14 days after their last exposure to that person.

Can an infected person spread COVID-19 before showing symptoms?

An infected person can spread COVID-19 starting 2 days before the person has any symptoms or tests positive. People who have COVID-19 don't always have obvious symptoms. A person is still considered a close contact even if they were wearing a mask while they were around someone with COVID-19.

How long should I wait to get tested for COVID-19 after being exposed if I am fully vaccinated?

- If you have been fully vaccinated and around someone who has COVID-19 (close contact), you do not need to stay away from others (quarantine), or be restricted from work unless you develop COVID-like symptoms. We recommend that you get tested 3-5 days after your last exposure to someone with COVID-19.

New Covid Symptom Appears Only In Vaccinated People, Identified In UK Study

Should I get tested after a close contact with someone who has COVID-19 if I am fully vaccinated?

• If you've had close contact with someone who has COVID-19, you should get tested 3-5 days after your exposure, even if you don't have symptoms. You should also wear a mask indoors in public for 14 days following exposure or until your test result is negative.

What should you do if you have been around a person with COVID-19?

For Anyone Who Has Been Around a Person with COVID-19

Anyone who has had close contact with someone with COVID-19 should stay home for 14 days after their last exposure to that person.

What is an asymptomatic case of COVID-19?

An asymptomatic case is an individual who has a laboratory confirmed positive test and who has no symptoms during the complete course of infection.

What is considered a close contact of someone with COVID-19?

For COVID-19, a close contact is anyone who was within 6 feet of an infected person for a total of 15 minutes or more over a 24-hour period (for example, three individual 5-minute exposures for a total of 15 minutes).

What steps should you take after coming into close contact with someone who tested positive for COVID-19?

• Stay home for 14 days after your last contact with a person who has COVID-19.
• Watch for fever (100.4◦F), cough, shortness of breath, or other symptoms of COVID-19.
• If possible, stay away from others, especially people who are at higher risk for getting very sick from COVID-19.

Am I considered a close contact for COVID-19 if I was wearing a mask?

A person is still considered a close contact even if they were wearing a mask while they were around someone with COVID-19. You can call, text, or email your contacts. By letting your close contacts know they may have been exposed to COVID-19, you are helping to protect everyone.

How long should I stay in quarantine after exposure to COVID-19?

Quarantine means staying home for 14 days after you are exposed to someone who has been diagnosed with COVID-19. This is because you can be infected with the virus that causes COVID-19 but may not show symptoms for up to 14 days. Even though you may not show symptoms, you can still spread the virus.

How long can COVID-19 linger in the air?

The smallest very fine droplets, and aerosol particles formed when these fine droplets rapidly dry, are small enough that they can remain suspended in the air for minutes to hours.

What does it mean that someone is asymptomatic?

Someone who is asymptomatic has the infection but no symptoms and will not develop them later. Someone who is pre-symptomatic has the infection but does not have any symptoms yet.

How long does isolation last for asymptomatic people during the COVID-19 pandemic?

For people who are infected but asymptomatic (never develop symptoms), isolation and precautions can be discontinued 10 days after the first positive test.

What percentage of COVID-19 transmissions are from asymptomatic cases?

In the first mathematical model to incorporate data on daily changes in testing capacity, the research team found that only 14% to 20% of COVID-19 individuals showed symptoms of the disease and that more than 50% of community transmission was from asymptomatic and pre-symptomatic cases.

What should I do if I've been exposed to a person with COVID-19 and I have fully recovered from a COVID-19 infection in the previous 90 days?

Someone who tested positive for COVID-19 with a viral test within the previous 90 days and has subsequently recovered and remains without COVID-19 symptoms does not need to quarantine. However, close contacts with prior COVID-19 infection in the previous 90 days should:
• Wear a mask indoors in public for 14 days after exposure.
• Monitor for COVID-19 symptoms and isolate immediately if symptoms develop.
• Consult with a healthcare professional for testing recommendations if new symptoms develop.

What should vaccinated people do if they come in contact with someone who has COVID-19?

Fully vaccinated people who have come into close contact with someone with COVID-19 should be tested 3-5 days following the date of their exposure and wear a mask in public indoor settings for 14 days or until they receive a negative test result. They should isolate if they test positive.

Can someone test negative and later test positive on a viral test for COVID-19?

Yes, it is possible. You may test negative if the sample was collected early in your infection and test positive later during this illness. You could also be exposed to COVID-19 after the test and get infected then. Even if you test negative, you still should take steps to protect yourself and others. See Testing for Current Infection for more information.

How long can COVID-19 survive on surfaces?

Data from surface survival studies indicate that a 99% reduction in infectious SARS-CoV-2 and other coronaviruses can be expected under typical indoor environmental conditions within 3 days (72 hours) on common non-porous surfaces like stainless steel, plastic, and glass .

Does COVID-19 live in the air?

Research shows that the virus can live in the air for up to 3 hours. It can get into your lungs if someone who has it breathes out and you breathe that air in.

How long does COVID-19 stay active at room temperature?

A study published in found that at room temperature, COVID-19 was detectable on fabric for up to two days, compared to seven days for plastic and metal.

Should I get tested for COVID-19 if I was in close contact with a positive case?

•Viral testing is recommended for close contacts of persons with COVID-19.

Who do masks protect from COVID-19: the wearer, others, or both?

We've known for some time that masks help prevent people from spreading the coronavirus to others. Based on an analysis of existing information, a new study contends that masks may also protect mask wearers from becoming infected themselves.

Different masks, writes the study author, block viral particles to varying degrees. If masks lead to lower "doses" of virus being inhaled, then fewer people may become infected, and those who do may have milder illness.

Researchers in China experimented with hamsters to test the effect of masks. They put healthy hamsters and hamsters infected with SARS-CoV-2 (the COVID-19 coronavirus) in a cage, and separated some of the healthy and infected hamsters with a barrier made of surgical masks. Many of the "masked" healthy hamsters did not get infected, and those who did got less sick than previously healthy "maskless" hamsters.

How can surgical masks protect me from COVID-19?

If worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain germs (viruses and bacteria), keeping it from reaching your mouth and nose. Surgical masks may also help reduce exposure of your saliva and respiratory secretions to others.