SurveySeroprevalence says: Omicron Infected Lots of People

You probably guessed that, but it’s good to have seroprevalence data, even if the CDC website hasn’t been updated yet. From EID (boldface mine):

Sera are tested for anti-nucleocapsid (anti-N) antibodies, which are produced in response to infection but are not produced in response to COVID-19 vaccines currently authorized for emergency use or approved by the Food and Drug Administration in the United States….

During September–December 2021, overall seroprevalence increased by 0.9–1.9 percentage points per 4-week period. During December 2021–February 2022, overall U.S. seroprevalence increased from 33.5% (95% CI = 33.1–34.0) to 57.7% (95% CI = 57.1–58.3). Over the same period, seroprevalence increased from 44.2% (95% CI = 42.8–45.8) to 75.2% (95% CI = 73.6–76.8) among children aged 0–11 years and from 45.6% (95% CI = 44.4–46.9) to 74.2% (95% CI = 72.8–75.5) among persons aged 12–17 years (Figure). Seroprevalence increased from 36.5% (95% CI = 35.7–37.4) to 63.7% (95% CI = 62.5–64.8) among adults aged 18–49 years, 28.8% (95% CI = 27.9–29.8) to 49.8% (95% CI = 48.5–51.3) among those aged 50–64 years, and from 19.1% (95% CI = 18.4–19.8) to 33.2% (95% CI = 32.2–34.3) among those aged ≥65 years.

What’s terrifying is that between the end of January and the end of February, seroprevalence increased from 43.3% to 57.7%, which is a fourteen percent increase, and is a monthly increase seven to thirteen times higher than the monthly increases from September through December 2021.

Here’s how it breaks down by age:

But kids don’t get COVID something something…. Anyway, one other thing to keep in mind is that roughly forty percent (plus or minus) of Americans still haven’t contracted COVID even after two years of a pandemic, lots of willful ignorance (and outright malevolence), and crappy policy, so it’s not inevitable.

Some methods notes: From the paper:

First, convenience sampling might limit generalizability. Second, lack of race and ethnicity data precluded weighting for these variables. Third, all samples were obtained for clinical testing and might overrepresent persons with greater health care access or who more frequently seek care. Finally, these findings might underestimate the cumulative number of SARS-CoV-2 infections because infections after vaccination might result in lower anti-N titers, and anti-N seroprevalence cannot account for reinfections.

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