Protection from prior infection significantly reduced against Omicron
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Omicron reinfections than reinfection with other variants, according to a new study by Qatari researchers that has not yet been peer-reviewed.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.