COVID-19Common question

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.

Is there asymptomatic transmission of the coronavirus disease?

Recent epidemiologic, virologic, and modeling reports support the possibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission from persons who are presymptomatic (SARS-CoV-2 detected before symptom onset) or asymptomatic (SARS-CoV-2 detected but symptoms never develop).

How long will asymptomatic people test positive for COVID-19?

In general, asymptomatic people may test positive for 1-2 weeks, while those with mild-to moderate disease often continue to test positive for a week or more after this.

Do people without symptoms have the same amount of coronavirus in their bodies as people with symptoms?

"Without symptoms" can refer to two groups of people: those who eventually do have symptoms (pre-symptomatic) and those who never go on to have symptoms (asymptomatic). During this pandemic, we have seen that people without symptoms can spread the coronavirus infection to others.

A person with COVID-19 may be contagious 48 to 72 hours before starting to experience symptoms. In fact, people without symptoms may be more likely to spread the illness, because they are unlikely to be isolating and may not adopt behaviors designed to prevent spread.

How many patients with COVID-19 have no symptoms?

Multiple studies indicate that a significant portion of Covid-19 patients are asymptomatic—and that could mean the disease's fatality rate is lower than previously thought.

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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.

When does a person with COVID-19 start being contagious?

Researchers estimate that people who get infected with the coronavirus can spread it to others 2 to 3 days before symptoms start and are most contagious 1 to 2 days before they feel sick.

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 the difference between people who have asymptomatic or pre-symptomatic COVID-19?

Both terms refer to people who do not have symptoms. The difference is that ‘asymptomatic’ refers to people who are infected but never develop any symptoms, while ‘pre-symptomatic’ refers to infected people who have not yet developed symptoms but go on to develop symptoms later.

What is the difference between presymptomatic and asymptomatic cases of COVID-19?

A presymptomatic case of COVID-19 is an individual infected with SARS-CoV-2 who has not yet exhibited symptoms at the time of testing but who later exhibits symptoms during the course of the infection.

An asymptomatic case is an individual infected with SARS-CoV-2 who does not exhibit symptoms at any time during the course of infection.

How long are you contagious if you are an asymptomatic carrier of COVID-19?

The Centers for Disease Control and Prevention recommends a 10- to 14-day quarantine period for anyone testing positive for the virus. The research from South Korea, however, found that asymptomatic people were contagious for about 17 days and those with symptoms were contagious for up to 20 days.

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.

Can patients who have recovered from COVID-19 continue to have detectable SARS-CoV-2 RNA in upper respiratory specimens?

• Patients who have recovered from COVID-19 can continue to have detectable SARS-CoV-2 RNA in upper respiratory specimens for up to 3 months after illness onset in concentrations considerably lower than during illness; however, replication-competent virus has not been reliably recovered and infectiousness is unlikely.

What is asymptomatic transmission?

An asymptomatic laboratory-confirmed case is a person infected with COVID-19 who does not develop symptoms. Asymptomatic transmission refers to transmission of the virus from a person, who does not develop symptoms.

There are few reports of laboratory-confirmed cases who are truly asymptomatic, and to date, there has been no documented asymptomatic transmission. This does not exclude the possibility that it may occur. Asymptomatic cases have been reported as part of contact tracing efforts in some countries.

How long does it take for symptoms of COVID-19 to appear after exposure?

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

What does presymptomatic mean in relation to COVID-19?

Presymptomatic means you're infected, and you're shedding the virus. But you don't yet have symptoms, which you ultimately develop. Unfortunately, the evidence suggests that you may be most contagious in the presymptomatic stage before you have any symptoms.

What does pre-symptomatic transmission of COVID-19 mean?

The incubation period for COVID-19, which is the time between exposure to the virus (becoming infected) and symptom onset, is on average 5-6 days, however can be up to 14 days. During this period, also known as the “pre- symptomatic” period, some infected persons can be contagious. Therefore, transmission from a pre-symptomatic case can occur before symptom onset.

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.

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.

How common is asymptomatic COVID-19 infection?

An analysis of multiple studies in the journal, PLOS Medicine, found that approximately 20-to-30% people infected with SARS-CoV-2 remained asymptomatic throughout the course of their infection.

How does COVID-19 mainly spread?

Spread of COVID-19 occurs via airborne particles and droplets. People who are infected with COVID can release particles and droplets of respiratory fluids that contain the SARS CoV-2 virus into the air when they exhale (e.g., quiet breathing, speaking, singing, exercise, coughing, sneezing).

Can you still have detectable SARS-CoV-2 RNA after recovering from COVID-19?

Some people who have recovered may have detectable SARS-CoV-2 RNA in upper respiratory specimens for up to 3 months after illness onset, albeit at concentrations considerably lower than during illness, in ranges where replication-competent virus has not been reliably recovered and infectiousness is unlikely.

Are recovered persons with persistent positive test of COVID-19 infectious to others?

Persons who have tested persistently or recurrently positive for SARS-CoV-2 RNA have, in some cases, had their signs and symptoms of COVID-19 improve. When viral isolation in tissue culture has been attempted in such persons in South Korea and the United States, live virus has not been isolated. There is no evidence to date that clinically recovered persons with persistent or recurrent detection of viral RNA have transmitted SARS-CoV-2 to others.

Despite these observations, it’s not possible to conclude that all persons with persistent or recurrent detection of SARS-CoV-2 RNA are no longer infectious. There is no firm evidence that the antibodies that develop in response to SARS-CoV-2 infection are protective. If these antibodies are protective, it’s not known what antibody levels are needed to protect against reinfection.

Can people who were previously diagnosed with COVID-19 be re-infected with it?

CDC is aware of recent reports indicating that persons who were previously diagnosed with COVID-19 can be re-infected. These reports can understandably cause concern. The immune response, including duration of immunity, to SARS-CoV-2 infection is not yet understood.

Should I get tested for COVID-19 if I have no symptoms and I've been exposed?

Even if you don't have symptoms, you should get tested 3-5 days after your exposure. If you need help, health department staff can provide information about the best time to get a vaccine and resources for COVID-19 testing in your area. If your test result is positive, you have COVID-19 and should isolate for 10 days.