(NEXSTAR) – Early studies indicate omicron may have a shorter incubation period than prior coronavirus variants, but does that affect how long someone is contagious with the virus?
The Centers for Disease Control and Prevention recently shortened its isolation guidelines, citing evidence that COVID is most contagious 1 to 2 days before someone starts feeling symptoms and 2 to 3 days after. That change was announced in late December, before the height of the omicron peak in the U.S.
Even now, as the peak appears to have passed, there’s still much to learn about the latest variant. Early science does seem to indicate omicron’s timeline is sped up from earlier variants. Because omicron appears to cause symptoms faster than previous variants, people with omicron could start becoming contagious as soon as one day after infection. With older variants, people became contagious two to four days after infection.
Someone is most contagious with the virus when their viral load peaks. According to a study published in the New England Journal of Medicine, with the delta variant, viral load peaked about three days after infection. Six days later, people were typically no longer contagious.
One study has found evidence that timeline is also sped up with omicron, but more research is needed. The study’s authors noted it’s possible the quicker recovery time (and therefore shorter contagious period) could also be because so many more people are vaccinated against the virus at this phase of the pandemic.
With any variant, you’re less likely to be contagious as your symptoms subside. That science informs the CDC guidelines on how long you need to isolate. If you test positive for COVID (or are experiencing symptoms and are presumed to be positive), you need to self-isolate for five days. After five days, you can end isolation if you’ve been fever-free for 24 hours (without using a fever suppressant like Tylenol) and your other symptoms are getting better.
If you test positive after five days of isolating, the CDC says to keep isolating for an additional five days. After 10 days, you should be in the clear. “People are no longer considered infectious (able to spread the virus that causes COVID-19) after 10 days have passed since they became infected,” the CDC told Nexstar.
The Associated Press contributed to this report.