How Long You’re Contagious, When to Quarantine and More – NBC Chicago

As people continue to recover from holiday gatherings and others return to the workplace in the new year, many are wondering what the schedule looks like if they develop a COVID-19 infection or are exposed to someone who has it.

When are people with coronavirus most contagious and how long can they spread it? When should you get tested after exposure and how long should you quarantine, if at all?

Here’s what we know.

When are people with COVID most contagious?

The Centers for Disease Control and Prevention released new guidelines last month, shifting the timing of isolation and quarantine because some experts say the time when people are most contagious is earlier.

“It takes less time from when someone is exposed to COVID to potentially develop an infection. It takes less time to develop symptoms, it takes less time for someone to be contagious and it takes, for many people, less time to recover This is largely due to many more people being vaccinated,” said Chicago Department of Public Health Commissioner Dr. Allison Arwady.

For those with no symptoms, CDC guidelines say they are considered contagious at least two days before they test positive.

“It has to do with the CDC data that really showed that after seven days there is virtually no risk of transmission at this point,” Arwady said. “And in that window of five to seven days, you know, there are some depending on whether people have been vaccinated, underlying conditions, etc., but the risk goes down a lot and the feeling is that in the general population, combined with masking etc. the risk is really very low.”

When is the best time to get tested after exposure?

The CDC says anyone who may have been exposed to someone with COVID should be tested five days after exposure or as soon as symptoms appear.

“If symptoms appear, individuals should immediately self-quarantine until a negative test confirms that the symptoms are not attributable to COVID-19,” the guidelines state.

Illinois Department of Public Health Director Dr. Ngozi Ezike said incubation times could change, but those who test early should continue testing even if they test negative.

“We may be learning that the incubation time could be a bit shorter. So maybe you would test at two days,” Ezike said. “Obviously if you’re symptomatic you test straight away. But you know, if you want to test at two days, but that negative test… the two days shouldn’t make you think, ‘oh well, I’m clear.’ You know, you might want to test again and of course the symptoms that you can’t ignore – scratchy throat, headaches, all kinds of symptoms – anything new can be a symptom of this new disease.”

How soon can symptoms appear?

According to previous CDC guidelines, symptoms of COVID can appear anywhere from two to 14 days after a person has been exposed to the virus.

Anyone with symptoms should get tested for COVID-19.

How long should you quarantine or self-isolate?

First, those who think they have been in contact with someone who has COVID and is not vaccinated should self-quarantine. Those who test positive, regardless of their vaccination status, should self-isolate, according to the Centers for Disease Control and Prevention.

Here is the breakdown:


Those who have been within 6 feet of someone with COVID for a cumulative total of at least 15 minutes in a 24-hour period must quarantine for five days if unvaccinated or longer six months after their second dose, according to updated CDC guidelines released Monday.

Once this period is over, they must participate in strict mask use for another five days.

Previously, the CDC said people who weren’t fully vaccinated and who came into close contact with an infected person should stay home for at least 10 days.

Before last month, fully vaccinated people — who the CDC defined as having two doses of the Pfizer or Moderna vaccines, or one dose of the Johnson & Johnson vaccine — could be exempt from quarantine.

Those who are both fully vaccinated and boosted do not need to quarantine if in close contact with someone with COVID, but should wear a mask for at least 10 days after exposure. The same goes for those who are fully vaccinated and not yet eligible for their booster.

However, local health authorities can also make the final decision on the duration of a quarantine. And testing can play a part.

The Illinois Department of Health has said it will adopt the CDC’s revised guidance on isolation and quarantine for COVID.

In Chicago, those who travel to or from certain parts of the country and are not vaccinated must quarantine upon arrival in the city, but how long they must do so depends on whether or not they get tested. screening for COVID.


COVID-positive people should stay home for five days, the CDC said last month, changing the guidelines from the previously recommended 10 days.

At the end of the period, if you have no symptoms, you can resume your normal activities but you must wear a mask everywhere – even at home around others – for at least five more days.

If you still have symptoms after being isolated for five days, stay home until you feel better, then start your five days of mask-wearing at any time.

So how do you calculate your isolation period?

According to the CDC, “Day 0 is your first day of symptoms.” This means that day 1 is the first full day after your symptoms started.

For those who test positive for COVID but have no symptoms, day 0 is the day of the positive test. Those who develop symptoms after testing positive, however, must start their calculations again, with day 0 then becoming the first day of symptoms.

When should you call a doctor?

The CDC urges those who have or may have COVID to watch for emergency warning signs and seek immediate medical attention if they have symptoms, including:

  • Difficulty breathing
  • Persistent pain or pressure in the chest
  • New confusion
  • Inability to wake or stay awake
  • Pale, gray, or blue skin, lips, or nail beds, depending on skin tone

“This list does not contain all possible symptoms,” the CDC says. “Please call your doctor for any other symptoms that are serious or cause you concern.”

You can also let the operator know that you think you or someone you are caring for has COVID.

What if you get a positive result using a home test?

Those who test positive using a home test are urged to follow the latest CDC guidelines and report results to their healthcare provider, who is responsible for reporting test results to the Department of Health. state health.

According to the Chicago Area Health Department, people should assume test results are accurate and should self-isolate from others to reduce the risk of spreading the virus.

“If you test positive for COVID-19, you should self-isolate,” Arwady said. “There’s no need to repeat a positive test at home in a medical setting. We don’t want people going to the emergency room just to get tested. Treat a positive as a positive, stay home and self-isolate. you for five days.”

When can you be with other people after having COVID?

If you had symptoms, the CDC says you can be with others after you isolate for five days and stop showing symptoms. However, you should continue to wear masks for five days to minimize risk to others.


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