Jan 7, 2022 - Health

Protection from prior infection significantly reduced against Omicron

Illustration of a person staring into the light at the end of a tunnel, the light is in the shape of a coronavirus cell.  
Illustration: Aïda Amer/Axios

Prior coronavirus infections appear to be much less protective against symptomatic Omicron reinfections than reinfection with other variants, according to a new study by Qatari researchers that has not yet been peer-reviewed.

Why it matters: If you're counting on your previous coronavirus infection to keep you from getting it again, don't.

The big picture: Initial studies have found that coronavirus vaccines — particularly without a booster shot — are much less effective against Omicron infections than other variants, although they appear to hold up well against severe disease.

  • This study suggests the same is true for people with prior infections, emphasizing the benefit of vaccines for this population.

By the numbers: The study found that prior infections were 90% effective against symptomatic reinfections for the Alpha variant, 92% effective for the Delta variant and only 56% effective for Omicron.

  • Effectiveness against hospitalization and death was 69% for Alpha, 100% for Delta and 88% for Omicron.

The bottom line: Omicron's remarkable ability to evade immune protection — either from vaccines or infection — goes a long way toward explaining its explosive case growth.

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