Can you get infected with Omicron if you previously had COVID? All signs point to yes

People lined up and received test kits to detect COVID-19 as they were distributed in New York on Dec. 23, 2021.Craig Ruttle/Associated Press

Omicron has swept through the United States with stunning speed, bringing with it a slew of fears from those worried they’ll contract it. But for those who have already weathered a case of COVID-19, there’s also big question: Can I get it again?

Research thus far indicates that the variant — which now constitutes over 98 percent of cases in the country after first being detected in California at the beginning of December — can evade the immunity conferred by both past infection and vaccination to a greater degree than previous mutations of the virus.

While vaccines and the antibodies developed after an infection can help to prevent an individual from becoming sick again, or developing more severe symptoms, public health experts warn that people should not let their guard down even if they have had COVID during an earlier stage of the pandemic.

How likely you are to become infected with Omicron if you already had COVID?

The overall risk related to Omicron “remains very high,” the World Health Organization documented in its latest report on the variant, noting that there is “mounting evidence that immune evasion contributes to the rapid spread.”

“Increased risk of reinfection has been reported in South Africa, the United Kingdom, Denmark, and Israel, all suggesting immune evasion against Omicron,” according to WHO.

Available evidence demonstrates that fully vaccinated individuals and those previously infected with COVID-19 “have a low risk of subsequent infection for at least six months,” according to the Centers for Disease Control and Prevention. But there is a caveat: the level of protection offered may not be the same for all variants.

A report from the Imperial College London COVID-19 response team that was released in mid-December found that the risk of reinfection with Omicron is approximately 5.4 times greater than that of Delta.

“This level of immune evasion means that Omicron poses a major, imminent threat to public health,” Neil Ferguson, a professor at the school, said in a news release.

Meanwhile, a small study from the CDC published in its Morbidity and Mortality weekly report at the beginning of December confirmed the possibility of reinfection with the variant. Of 43 cases attributed to Omicron, six had prior documented COVID-19 infections.

In another report released at the end of the month, the agency examined six people in a single household and found that of the five who previously had a bout with the virus and later became reinfected with Omicron, their symptoms were “similar to or milder than those during their first infection.”

Other studies published by researchers in both Scotland and South Africa have also demonstrated an elevated risk of reinfection with Omicron.

“You can get reinfected after having COVID-19, although it is less common in the first 90 days after infection,” Dean Blumberg, chief of pediatric infectious diseases at UC Davis Children’s Hospital, said in a question and answer about the variant. “However, if you’ve had COVID-19 and are then vaccinated, this decreases your chance of reinfection by about half.”

What makes Omicron so contagious compared to other variants?

Compared to Delta and other coronavirus variants, Omicron carries “an abundance of mutations” — about 50 in all — which may help contribute to its enhanced transmissibility, according to Yale Medicine. Of those mutations, 26 are unique to the variant and more than 30 are located on the spike protein, “which is the viral protein that vaccines train the immune system to recognize and attack.”

Data so far suggest that Omicron is four times as infectious as Delta — a variant that was shown to be twice as infectious as the original strain of COVID-19, said Edward Walsh, a professor at the University of Rochester Medical Center, in a question and answer session about the variant.

How much protection do vaccines seem to offer against Omicron?

At the moment, a single booster of one of the mRNA coronavirus vaccines — those offered by either Moderna or Pfizer — is “sufficient to protect against both Delta and Omicron,” Walsh said. However, he said it is unclear if more booster doses will be needed in the future.

Studies indicate that being vaccinated without a booster shot will not offer sufficient protection against Omicron. Even those who have been boosted have reported breakthrough infections amid the surge driven by the contagious variant.

Moderna, Pfizer-BioNTech, and Johnson & Johnson said Monday they are all continuing to develop booster shots that will specifically target Omicron.

The CDC said it expects that “anyone with Omicron infection can spread the virus to others, even if they are vaccinated or don’t have symptoms.” Despite this, vaccination remains the best way to protect yourself and reduce further spread.

“The good news is, for those who are immunized and boosted, we are winning the battle,” Dr. Gregory Poland, head of Mayo Clinic’s Vaccine Research Group, said in a question and answer about the variant. “Getting immunized is basically a weapon against this virus.”

In short: Experts recommend that everyone get vaccinated and boosted against the coronavirus — for the benefit of both themselves and those around them.