Thread by @DrEricDing

📍RE-INFECTION UPDATE: 20 cases of formal reinfection has now been documented (genome 🧬 sequence). Up +5 from just last week. Severity data shows 8 of 14 had a 2nd infection that’s more severe, 4 of 8 were moderate to severe; 3 of 14 less severe. #COVID19 bnonews.com/index.php/2020…

2) The 4 newest reinfections were even confirmed by a very very detailed investigation to undercover them by a @Cornell and @WHO team in Qatar. This reinfection is real folks.

3) And by detailed investigation- they literally turned over every rock from 15,808 people with multiple test swabs... and went thru 243 people medical records and did detailed analysis of these potential reinfections and 🧬 to find the 4 new reinfection cases. HARDCORE!

4) HUGE— they calculated risk of reinfection:

📌reinfection risk estimated at 0.01% (95% CI: 0.01-0.02%)

📌incidence rate of reinfection was estimated at 0.36 (95% CI: 0.28-0.47) per 10,000 person-weeks.

5) Conclusions: “SARS-CoV-2 reinfection can occur but is a rare phenomenon suggestive of a strong protective immunity against reinfection that lasts for at least a few months post primary infection.”

6) Followup- someone asked: what does “PERSON-WEEKS” mean? I means total human ‘lived time’ of either 10,000 people followed alive for 1 week or 100 people followed for 100 weeks...

7) Thus, incidence rate of reinfection of 0.36 per 10,000 person-weeks equals about:

📌1 reinfection per 30,000 person weeks

📌1 reinfection per 1000 recovered patients followed for 30 weeks.

📌1 reinfection per 10000 recovered patients followed for 3 weeks

8) But thus also assumes active community infection rates of similar magnitude of course. If the epidemic disappears then the reinfection risk goes down to nothing too.