Averages from alpha to omicron

Averages from alpha to omicron

The strains of SARS-CoV-2 that cause the spread of coronavirus (COVID-19) in 2023 typically take about three days from exposure and symptoms to appear. This incubation period is shorter than previous virus strains. It may take up to a week before an at-home antigen test comes back positive.

This article will review the incubation periods of different SARS-CoV-2 virus variants, from Alpha to Omicron, after exposure and how long it typically takes to get a positive test. You’ll also discuss several reasons why times may vary from person to person, including vaccination and booster status, general health, and whether you’ve had COVID-19 before.

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Incubation period for COVID-19: How soon after exposure can symptoms begin?

Terminology related to viral diseases varies. Here are some key terms used in this article to clarify their meaning:

  • The virus The incubation period It is how long it takes for symptoms to begin after exposure.
  • the The time after exposure before you get a positive test Over-the-counter antigen testing can be longer or shorter than the incubation period before symptoms begin.
  • the Quarantine period A requirement by your work, school, or local government that you stay away from others after you have been exposed to a virus or tested positive.
  • The virus Infection It is how easily it spreads between people, which is affected by your immune status and general health. The virus can be transmitted before and after symptoms appear, so the virus Contagious period The incubation or symptomatic periods can be longer.
  • The virus Transmission route How it spreads between people, through the air or from surfaces. You can transmit the virus to another person while you are infected with the virus.

What to do in the incubation period after exposure

After you’re exposed to the virus, there’s not much you can do to determine whether you will get sick. It’s always a good idea to take good care of yourself, including eating healthy and drinking plenty of water.

Get tested for coronavirus (COVID-19) regularly and monitor your symptoms such as fever before leaving home to make sure you don’t inadvertently spread the virus to other people.

You may want to request or get more coronavirus (COVID-19) tests if you become infected. You will need to get tested regularly if you are still positive before seeing other people, especially those with a weakened immune system.

According to the Centers for Disease Control and Prevention (CDC), symptoms of coronavirus (COVID-19) may appear anywhere from 2 to 14 days after exposure to the virus.

A review of studies conducted from 2020 to March 2022 indicated an average incubation period for COVID-19 of six to seven days, ranging from 1.8 to 18.87 days. The average incubation period was shortened as new strains spread, with Omicron averaging 3.42 days.

Variants and strains to know

As COVID-19 spreads from person to person, it mutates (changes genetically) along the way. These mutations can change the virus enough for it to evolve into a new strain.

New strains, or variants, can have changes in common symptoms, how easily they spread, and how long they take to cause illness.

Several variants have been circulating since 2020. A variant of concern (identified by the CDC) transmits between people faster, is more virulent (has a greater ability to cause disease), and has shown vaccine resistance or immunity from prior infection, or neither. It does not appear in current tests.

The average incubation periods for key variants from the 2022 review study were as follows:

  • Alpha variable: 5.0 days
  • Trial version: 4.50 days
  • Variable delta: 4.41 days
  • Omicron variant: 3.42 days

The 2023 Covid strains, including Omicron and its subvariants, appear to be more transmissible due to their shorter incubation period. Studies with Omicron suggest a shorter incubation period with an average of three to four days after exposure before symptoms appear.

The variant circulating in most regions in late 2023 was Omicron-5, or EG.5, and was first reported in February 2023. Incubation period data is not yet available for the EG.5 subvariant. However, experts say it appears to behave similarly to previous versions of Omicron. The incubation period for Omicron-5 is about three to four days.

Symptoms of COVID-19

Symptoms of coronavirus infection (COVID-19) can vary from asymptomatic (no symptoms) to mild or severe.

If you have been vaccinated, received a booster shot (received a booster shot), or had COVID-19 in the past, your symptoms are likely to be less severe. But if you have a change in your immune system (for example, pregnancy, taking a new medication, or a new illness), your symptoms may be more serious than a previous infection.

Many symptoms are very similar to those of other upper respiratory viruses, including the common cold, influenza, and respiratory syncytial virus (RSV), which have similar seasonality (transmission often peaks in fall and winter). If you have symptoms, over-the-counter tests can help determine if you have COVID-19.

The first signs and symptoms of Omicron infection include sore throat, dry cough, and fever. The most common symptoms of COVID-19 are:

  • Fever or chills
  • sore throat
  • cough
  • Shortness of breath or difficulty breathing
  • exhaustion
  • Muscle or body aches
  • headache
  • Congestion, runny nose or sneezing
  • Nausea or vomiting
  • Diarrhea

Incubation period for COVID-19: How long will a test be positive after exposure?

You should begin testing for coronavirus (COVID-19) after waiting at least five days after possible exposure to a sick person. Do the test again after a day or two. Then take the test again after another two days. You should plan to have three tests within five days to make sure you’re safe.

It may take a week or more to get a positive result on a home COVID-19 antigen test after exposure or symptoms. A laboratory PCR (polymerase chain reaction) test will show a positive result much sooner. You should wear a mask when you are around other people for 10 days after possible exposure.

Frequently asked questions and answers about the incubation period of the Coronavirus

When you’ve been exposed to COVID or been in contact with someone who is sick, you’re bound to have a lot of questions. Here are answers to some common questions people have about coronavirus incubation periods.

How does the incubation period of the Coronavirus compare to other viruses?

Coronavirus appears to have a longer incubation period than other common respiratory diseases. The different incubation periods for the virus include:

Can I spread coronavirus during the incubation period?

Asymptomatic and asymptomatic transmission of coronavirus (COVID-19) has been an important factor in the spread of the pandemic. This virus appears to spread quickly before it causes symptoms. If you’re exposed to COVID, you can spread it, even if you don’t feel sick, and perhaps even if you never feel sick.

This coronavirus contagious period lasts from before you start to feel sick until your at-home antigen test turns negative.

Does the incubation period change depending on vaccination status?

If you are vaccinated and immunized against COVID-19, you are more likely to have a milder infection. But studies indicate that the incubation period for the virus will remain the same.

Does the incubation period change depending on age?

Some studies have indicated that the average incubation period in people 60 or older may be longer, about seven to eight days, compared to the general population. Studies have also shown that children under the age of 18 may have an incubation period of 8 to 9 days.

Should I contact my healthcare provider if I get a positive coronavirus test result?

If you are in generally good health and are currently receiving coronavirus (COVID-19) vaccines, there is no need to seek medical care after a positive coronavirus test result.

Contact your health care provider if you are at high risk for severe infection, for example, if you have a weak immune system, are over 65 years of age, or have not been vaccinated. They may prescribe Baxlovid (nermatrelivir/ritonavir), an oral antiviral tablet to treat COVID-19 infection. It can aid recovery and reduce the risk of serious complications.

If you see any of these emergency warning signs, seek immediate medical help:

  • You are having difficulty breathing.
  • You have chest pain or pressure that doesn’t go away.
  • You are experiencing confusion.
  • You have difficulty waking up or staying awake.
  • Your skin, lips, or nails turn pale, gray, or blue.

How long should I isolate if I test positive for coronavirus?

You’ll need to let your workplace or school know if you’ve been exposed to coronavirus and get a positive test result. They may want you to stay home for a certain period of time.

You should avoid being around others while testing for coronavirus. This includes other people in your home. Try to stay in one room, away from others. Wear a mask if you will be around others. Stay at home to avoid transmitting the virus. If you need to leave the house, wear a mask.

Day zero is the day you first developed symptoms, or, if you don’t have symptoms, the day you first tested positive for coronavirus (COVID-19). CDC guidelines for isolation are as follows:

  • You can end isolation on day 5 if you have no symptoms or your symptoms are improving and you have not had a fever for 24 hours without taking fever-reducing medicine.
  • If your symptoms do not improve, isolate yourself until you improve and have been fever-free for 24 hours without taking fever-reducing medicine.
  • If you have moderate symptoms such as difficulty breathing, isolate yourself for the tenth day.
  • If you are hospitalized or have a weakened immune system, isolate yourself through day 10 or when your health care provider allows you to do so.

For anyone after isolation, continue to wear a mask when around others (at home and in public) until at least day 11.


The incubation periods of COVID-19 variants vary. In general, the incubation period becomes shorter. Symptoms of newer strains such as Omicron usually appear about three to four days after exposure. The newer Omicron-5 variant is similar to the original Omicron strain.

Getting a positive coronavirus test at home can take anywhere from a week to 10 days. Regular testing after potential exposure can reduce the risk of spreading the virus.

The first symptoms of coronavirus are usually a dry cough, sore throat, and fever. It is similar to other respiratory viruses that spread in the fall and winter. The incubation period for coronavirus tends to be a little longer than some of these other viruses.

Studies suggest that the COVID-19 vaccine and supportive condition do not change the incubation period, but factors such as age may do. Older adults and children may have a longer incubation period for the coronavirus.

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