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Your risk of getting Corona again in the next wave is lower if you already had Omicron

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Many people around the world have already been infected with omicron. A particularly contagious variant, BA.2, is now spreading and is already dominating other versions of the omicron variant, including BA.1, BA 1.1, and B.1.529, in both Europe and the Northeast US.

Since pandemic restrictions in Europe were mostly lifted this spring, there has been a significant increase in BA.2 infections across the continent. Many of those who have been infected in recent months are now wondering if they could get omicron again. The answer is probably no. You can read about the findings so far in the following text.

Reinfection with omicron is possible but rare

A Danish research team found that reinfection with BA.2 after BA.1 can occur, but is quite rare. Analyzing data from more than 1.8 million cases between November 2021 and February 2022, they discovered only 47 reinfections with BA.2 after BA.1. These primarily affected “young, unvaccinated people,” the researchers write. The same is true in England, where only 43 potential reinfections were detected among more than 500,000 sequenced samples of BA.1 and BA.2 collected between November and the end of February. However, these dates are still preliminary.

Despite these reassuring statistics, it is important to note that the studies were conducted over a very short period of time. It is not clear how long omicron immunity lasts and how well it actually works in all people.

Those most at risk are the unvaccinated

Some laboratory studies using blood samples have shown that BA.1 infection provides adequate cross-protection against BA.2. Once again, not much data is available. In a short article published March 16 in the New England Journal of Medicine (NEJM), blood samples from 24 boosted, vaccinated people who had never had corona and eight people suspected of having BA.1 were examined. All but one were vaccinated.

This study suggests the following:

  • People most at risk for BA.2 are unvaccinated people who have not previously been infected with BA.1.

  • Booster shots appear to be useful in raising antibody levels against BA.1 and BA.2 in people who have never been infected.

  • People with the best protection against BA.2 were vaccinated, boosted, and people who had been previously infected.

  • On average, vaccinated study participants with a prior COVID-19 infection (presumably BA.1) had more than three times higher levels of neutralizing antibodies against BA.2 than all others.

These results suggest that there is a “significant level of cross-reactive natural immunity” to BA.2 from BA.1, according to the research team.

Booster injections will probably work just as well as other versions of Omicron

From the New England Journal of Medicine article mentioned above, it appears that booster shots against BA.2 work almost as well as they do against BA.1. Data from the omicron outbreak, which peaked earlier this year, also suggests that boosted people are very well protected against severe cycles of omicron, even without prior infection.

The only question is how quickly the effect of the booster injection wears off given the time that has passed since the third injection (or the second injection for those who received Johnson & Johnson).

“Hybrid” immunity shows that vaccination or booster vaccination of recovered people has benefits

A much larger preliminary study, based on vaccination and infection data from across the country of Qatar, was published online on Tuesday. It has not yet been peer-reviewed, but like the NEJM article, it suggests that the best protection against omicron variants is prior infection or a recent booster shot.

The study shows the following for the period between the end of December and the end of February:

  • A previous infection with Corona reduced the risk of infection with BA.2 by 46 percent.

  • Vaccination plus a recent booster shot reduced the risk of infection by 52 percent.

  • So-called “hybrid” immunity (2-dose vaccination plus prior infection) reduced the risk of infection by 55 percent.

  • “Hybrid” immunity plus a recent booster shot reduced the risk of infection by 77 percent.

Two doses of the Biontech vaccine had no significant protective effect against omicron infection without a recent booster dose. However, fully vaccinated patients were still well protected from serious illness, hospitalization, and possible death during the wave of omicron. (Biontech’s vaccine is the most widely used COVID vaccine in Qatar.)


The omicron BA.2 variant should not be underestimated, especially as there are many people at risk who may not have contracted BA.1 and who could have a dangerous course with the more infectious BA.2. However, there is some new data suggesting that a previous infection with omicron may provide some immunity to BA.2 omicron, at least for a short time.

This text was translated from English by Marlene Schulze. You can find the original here.

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