As the U.S. experienced a surge of the omicron variant in the previous months, information emerged about the new strain, prompting guidance changes from the Centers for Disease Control and Prevention.
The CDC late last year shifted the time for COVID-19 isolation and quarantine as studies revealed the time frame when people are most contagious is earlier than other variants.
"It is taking less time from when someone is exposed to COVID to potentially develop infection," Chicago Department of Public Health Commissioner Dr. Allison Arwady previously stated. "It is taking less time to develop symptoms, it is taking less time that someone may be infectious and it is, for many people, taking less time to recover. A lot of that is because many more people are vaccinated."
The CDC says that its guidelines were updated to reflect growing evidence that suggests transmission of COVID-19 often occurs one to two days before the onset of symptoms and during the two to three days afterward.
For those without symptoms, CDC guidance states they are considered contagious at least two days before a positive test. The CDC states that anyone who may have been exposed to someone with COVID should test five days after their exposure, or as soon as symptoms occur.
According to earlier guidance, COVID symptoms can appear anywhere from two to 14 days after someone is exposed to the virus.
For most patients, symptoms appear to last three to five days, said Dr. Rahul Sharma, the emergency physician-in-chief at the NewYork-Presbyterian/Weill Cornell Medical Center.
"A lot of these patients are not having the symptoms for the 10 to 12 days that I saw when there were no vaccinations," he told NBC News. The doctor noted that, in general, symptoms appear to be shorter and milder in the vaccinated compared to the unvaccinated.
Under the latest CDC recommendations, those who have been within six feet of someone with COVID for a cumulative total of at least 15 minutes over a 24-hour period should quarantine for five days if unvaccinated, or if they are more than six months out from their second vaccine dose.
Once that period ends, they should partake in strict mask use for an additional five days.
Those who are both fully vaccinated and boosted do not need to quarantine if they are a close contact of 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 shot.
People who are positive for COVID should stay home for five days, the CDC said.
At the end of the period, if you have no symptoms, you can return to normal activities but must wear a mask everywhere — even at home around others — for at least five more days.
If you still have symptoms after isolating for five days, stay home until you feel better and then start your five days of wearing a mask at all times.