# Massive Seroprevalence and Omicron
**URL:** https://boards.straightdope.com/t/massive-seroprevalence-and-omicron/956067
**Category:** The Quarantine Zone
**Tags:** covid-quarantine
**Created:** [December 14, 2021, 7:15pm UTC](https://boards.straightdope.com/t/massive-seroprevalence-and-omicron/956067 "2021-12-14T19:15:23Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Tfletch1](https://boards.straightdope.com/u/Tfletch1)
#### Post date: [December 14, 2021, 7:15pm UTC](https://boards.straightdope.com/t/massive-seroprevalence-and-omicron/956067/1 "2021-12-14T19:15:23Z")
In several threads, many of you have surmised that Omicron seems to be more mild because of vaccines or prior exposures. This article refers to the first study coming out of South Africa in support of the anecdotal evidence of mild disease. Interestingly, it also mentions that some parts of South Africa have an average of **80% seroprevalence** due to previous exposures and probably a little more with vaccination.
> **[Omicron variant more resistant to vaccine but causes less severe covid, major...](https://www.washingtonpost.com/world/2021/12/14/south-africa-omicron-coronavirus/)**
>
> The study of the omicron coronavirus variant by South Africa's largest insurer involves 211,000 cases and is the most comprehensive to date.
That made me think of a paper on seroprevalence pre-delta and lower vaccination rate in the US. The combined vaccine+previous infection seroprevalence was 83%.
> **[Estimated US Infection- and Vaccine-Induced SARS-CoV-2 Seroprevalence Based...](https://jamanetwork.com/journals/jama/fullarticle/2784013)**
>
> This study estimates trends in SARS-CoV-2 seroprevalence related to infection and vaccination in the US population.
The are major caveats of these studies on blood donors (selection bias is a big one). However, the expected results may have played out on the ground during the delta surge. Obviously, areas in the South (LA, Ms, and Al) and midwest (Missouri and Arkansas) had significantly lower seroprevalence and it showed in their deadly delta surges. However, places the CA and the Northeast had much less deadly delta surges most likely due to high vaccination rates. Tons of news articles published the very low hospitalization rates of vaccinated vs unvaccinated. More importantly, combined seroprevalence may have been demonstrated in the Dakotas. I predicted that the Dakotas would have less deadly delta surges due to high infection rates and vaccination rates that were better than the South. That seems to be the case.
So, I decided to check the current seroprevalence on the CDC post-delta and it’s at least 90% in regions that have data.
> **[COVID Data Tracker](https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence)**
>
> CDC’s home for COVID-19 data. Visualizations, graphs, and data in one easy-to-use website.
So could we have a mild omicron surge? I still wear a mask in public because it’s not a big inconvenience. However, I haven’t been wearing a mask to my Dad’s house we’re all boosted. I plan to continue to eat outdoors at restaurants.
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### Author:  [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)
#### Post date: [December 14, 2021, 9:24pm UTC](https://boards.straightdope.com/t/massive-seroprevalence-and-omicron/956067/2 "2021-12-14T21:24:09Z")
> [@Tfletch1](#):
>
> So could we have a mild omicron surge?
That seems like the most likely possibility to me at this point, but there are still a lot of unknowns.