Thread by @miamalan

[Thread] 1. SA scientists have found that people who have had #COVID19 and is exposed to #SARSCoV2 again are 3x more likely to get reinfected if they were exposed to the #Omicron variant than to the Beta or #DeltaVariant. What does this mean?

Study: bit.ly/3rweewR

2. In easy speak it means the #OmicronVariant is 3x better than the Beta or #DeltaVariant at figuring out how to get around the protection that our antibodies offer against getting reinfected with #COVID. (These are antibodies we get after natural infection, not vaccination.)

3. In science speak it means the #OmicronVariant poses a 3-fold increase in relative risk for reinfection (when compared to the Beta or #DeltaVariant).

4. So your relative risk of getting reinfected with the #OmicronVariant is 3x what it was to get reinfected with the Beta or #DeltaVariant. (NB: This doesn’t apply to getting infected for the 1st time, only to getting infected again after you’ve already had #COVID19).

5. How do scientists know that? They collected data from 2,796,982 people in SA who tested positive for #COVID19 between 4 March 2020 and 90 days before 27 November.
Study: bit.ly/3rweewR

6. Scientists compared the relative risk of reinfection during the 2nd and 3rd wave to the relative risk of reinfection between the beginning of October 2021 and the end of November (the time period that’s associated with the emergence of the #OmicronVariant).

7. Of the 2,796,982 positive #COVID19 test results that scientists looked at 35,670 were suspected reinfections. During Oct and Nov the risk of people who had #COVID previously to get the disease again was 3 times higher than the risk of such people during the 2nd and 3rd wave.

8. During Wave 2 the Beta variant was dominant + during Wave 3 the #DeltaVariant. If we assume the #OmicronVariant was dominant in Oct + Nov 2021 then Omicron increases the relative risk of reinfection by 3x compared to the relative risk that the Beta or Delta variant posed.

9. What does an increased risk of reinfection tell us about the #OmicronVariant? It’s an indication that Omicron has developed the ability to get around the protection that the antibodies we get after natural infection offer @ getting reinfected. This is called immune escape.

10. What does the study not tell us?

The data only tells us something about the ability of #Omicron to sidestep/evade the antibodies produced after previous #COVID19 infection. It doesn't tell us if Omicron can do the same thing to the antibodies we develop after vaccination.

11. What does the study not tell us (cont)?
1. It doesn't tell us if the #OmicronVariant can get around the protection previous infection or vaccination offer against falling seriously ill with #COVID
2. It doesn't tell us which of the people who got reinfected was vaccinated

12. Find the preprint (so not yet peer reviewed) which was published on 2 Dec here: bit.ly/3rweewR