As omicron COVID-19 cases continue to spread and more people look for additional protection against the virus, what happens if you're infected before receiving your extra dose?
Do you need to wait to get your booster shot? If so, how long?
Here's the latest, according to Chicago Department of Public Health Commissioner Dr. Allison Arwady:
Do you need to wait to get your booster shot if you have or had COVID?
According to Arwady, people should wait 10 days after their positive test before getting their booster shot. This is in part due to isolation guidelines from the CDC.
"You should wait at least the 10 days, okay? During the time that you could be infectious," she said.
Arwady said that while those who recently recover from COVID do have antibodies, she still recommends getting a booster shot.
"Certainly if you've had a recent COVID infection, you've had your antibodies go up, but my recommendation to my staff, to my family, to everybody is particularly with the surge right now I would still recommending getting the booster," she said.
Should you get tested again before getting a booster shot after having COVID?
No, Arwady said, adding that guidance from the Centers for Disease Control and Prevention indicates people do not need to test out of quarantine or isolation and those who get a PCR test after COVID infection could test positive well after their active infection is over.
How are booster shots performing against omicron?
Moderna is working on a booster shot that will target the omicron variant of COVID for this fall as nations around the world prepare to distribute annual vaccinations against the virus.
"We are discussing with public health leaders around the world to decide what we think is the best strategy for the potential booster for the fall of 2022. We believe it will contain omicron," CEO Stephane Bancel told CNBC's "Squawk Box" on Monday.
Also Monday, Pfizer CEO Albert Bourla said a vaccine that targets the omicron variant will be ready in March, and the company has already begun manufacturing the doses.
"This vaccine will be ready in March," Bourla told "Squawk Box." "We [are] already starting manufacturing some of these quantities at risk."
Bourla said the vaccine will also target the other variants that are circulating. He said it is still not clear whether or not an omicron vaccine is needed or how it would be used, but Pfizer will have some doses ready since some countries want it ready as soon as possible.
Bourla said it's not clear whether a fourth dose is needed. He said Pfizer will conduct experiments to determine if another dose is necessary.
But Bancel on Thursday said the efficacy of boosters against COVID-19 will likely decline over time, and people may need a fourth shot in the fall to increase their protection.
Bancel said people who received their boosters last fall will likely have enough protection to get them through the winter, when new infections surge as people gather indoors to escape the cold.
However, Bancel said the efficacy of boosters will probably decline over the course of several months, similar to what happened with the first two doses.
"I will be surprised when we get that data in the coming weeks that it's holding nicely over time — I would expect that it's not going to hold great," Bancel said, referring to the strength of the booster shots.
Israel has made a fourth dose of Pfizer and BioNTech's vaccine available to people over the age of 60, people with compromised immune systems and health-care workers.
Israel found that a fourth dose of the vaccine increases antibodies that protect against the virus fivefold a week after receiving the shot.
Arwady said she recommends those who the Johnson & Johnson vaccine get an mRNA booster shot for maximum protection.
"For people who got J&J, I would recommend for your booster that you either get a Pfizer or Moderna," she said Tuesday. "When we looked at the studies, the increase in antibodies was better with a second dose of either Pfizer or Moderna. I don't care between those, and if you started with Pfizer, Moderna, I don't care which one you boost with. No major changes there, but for J&J especially, please get a booster and I would recommend Pfizer or Moderna."
Who is eligible for a booster shot and when?
The timing for when people can get their booster shot has shifted in the midst of the omicron surge.
Meanwhile, the U.S. is urging that everyone 12 and older get a COVID-19 booster as soon as they're eligible, to help fight back the hugely contagious omicron mutant that's ripping through the country.
The Illinois Department of Public Health on Thursday announced it would adopt the CDC's latest recommendation for those aged 12-15 years to get a booster dose five months after receiving the second dose.
“We know that COVID-19 vaccine booster doses can help provide ongoing protection against the Omicron variant,” IDPH Director Dr. Ngozi Ezike said in a statement. “Following the CDC’s recommendation, booster doses are encouraged for those aged 12-15 years who received their second dose of Pfizer-BioNTech vaccine five months ago.”
Chicago's health department followed suit Thursday.
"The Chicago Department of Public Health supports these decisions and encourages all eligible Chicagoans, age 12 and up, to get their booster dose now – no matter the type of COVID-19 vaccine they originally received," the Chicago Department of Public Health said in a release.
Boosters already were encouraged for all Americans 16 and older, but Wednesday the Centers for Disease Control and Prevention endorsed an extra Pfizer shot for younger teens — those 12 to 15 — and strengthened its recommendation that 16- and 17-year-olds get it, too.
The CDC is also recommending that children between the ages of 5 and 11 that are moderately or severely immunocompromised should get a third dose of the COVID vaccine 28 days after their second dose.
New U.S. guidelines say anyone who received two Pfizer vaccinations and is eligible for a booster can get it five months after their last shot, rather than the six months previously recommended.
The vaccine made by Pfizer and its partner BioNTech is the only U.S. option for children of any age.
On Friday, the FDA and CDC extended that timing to Moderna, shortening the timing for people seeking a booster shot of both mRNA vaccines to five months. The Johnson & Johnson booster interval is two months.
"CDC and FDA looked at data and said for for Pfizer and Moderna you can get a booster five months after, not six months," Arwady said. "You can get it at five months. There's vaccine available. Again, this is just around making sure that... in a surge, making sure we build that antibody level back up."
She added the the J&J booster shot remains available two months after the first dose.
"Has been the recommendation all along, it remains the recommendation," Arwady said.