February 27, 2024

Already had COVID? You can still get infected with the Omicron variant? What to know


We’re all exhausted, and this new coronavirus variant is making matters worse. But experts warn we can’t let our guards down because omicron has made one point clear: you can still contract the mutant despite prior infection and vaccination.

Research shows both coronavirus infection and vaccination offer immunity that can protect people from getting sick again, no matter the variant involved. But by how much and for how long remains unclear — a scientific gap only time may fill. Regardless of how immunity is acquired, there’s no telling who will or won’t develop effective antibodies, and why they last longer for some than for others.

But emerging evidence shows omicron does a better job at infecting people with a history of COVID-19 and evading vaccine’s defenses compared to other variants.

Experts caution that data collected so far is premature, so we’ll learn more about reinfection with omicron and how personal behaviors, including mask wearing and frequent testing, play a role as more time passes.

“For the unvaccinated, you’re looking at a winter of severe illness and death for yourselves, your families and the hospitals you may soon overwhelm,” Jeffrey Zients, White House COVID-19 response coordinator, said of the omicron surge during a Dec. 17 briefing. “Wear a mask in public indoor settings. Get vaccinated, get your kids vaccinated and get a booster shot when you’re eligible.”


Prior COVID-19 does offer some protection against reinfection, however, the omicron variant is stealing a large amount of power from so-called natural immunity.

A recent study of more than 12,000 suspected omicron infections in England found the risk of reinfection with the new variant is 5.4 times greater than that of delta. This suggests your past infection may offer just 19% protection against reinfection with omicron.

Before the new mutant emerged, prior infection provided 85% protection against getting COVID-19 a second time over six months, researchers with Imperial College London said in a news release.

A small study by the Centers for Disease Control and Prevention confirms reinfection with omicron is possible. Among 43 cases of the new variant, 14% previously tested positive for the coronavirus.

More research from South Africa, where omicron was first identified, shows an increased risk of reinfection with omicron.

Among 35,670 people with a history of at least two coronavirus infections, 47 experienced their third case in November, “which suggests that many third infections are associated with transmission of the Omicron variant,” researchers wrote in their non-peer-reviewed study posted Dec. 2. The same study found no evidence of increased reinfection risk with the delta variant just a month prior.


Researchers have found more than 30 mutations in the omicron variant’s spike protein — the part the coronavirus uses to enter human cells — which could be one of many reasons why it spreads so quickly.

A study from the University of Hong Kong found omicron replicates 70 times faster in people’s respiratory systems compared to delta and the original coronavirus strain a day after exposure.

The faster a virus makes copies of itself in your body, the faster it can spread between people, researchers said.

A company Christmas party in Norway revealed omicron’s incubation period — the time between exposure and symptom onset — was about three days, which is short compared to other variants and means omicron-infected people may get sicker faster.


Early data shows two doses of the Pfizer and Moderna vaccines offer lower protection against omicron, although they’re still effective at preventing severe disease; boosters increase it significantly. Meanwhile, the single-dose Johnson & Johnson shots offer little to no protection against omicron.

But you can still contract omicron despite complete vaccination — and booster status.

study out of Denmark shows 599 people with an omicron case out of 785 were fully vaccinated upon infection, and another 56 people had received their booster dose.

The CDC study of 43 omicron cases found 34 of them had occurred in fully vaccinated people, including 14 in people who had received their boosters.

“Early information definitely supports that there are enough mutations in the right place in the omicron variant to escape the maximal benefits of the vaccine,” Dr. Shira Abeles, an infectious disease specialist at UC San Diego Health in California, told Healthline. “But we are optimistic there will be partial protection. So yes, we may be more easily infected, but we remain optimistic that it won’t result in [a large increase in] hospitalizations and deaths.”

The CDC said it expects “anyone with omicron infection can spread the virus to others, even if they are vaccinated or don’t have symptoms.”

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