Thread by @DrEricDing

NEW—How good is “natural infection” immunity? 83% protection—People who have been infected by #COVID19 “may have immunity to the virus for around five months”, says study led by Public Health England (PHE). Possibly longer with more followup. 🧵
cnn.com/2021/01/14/hea…

2) “Two groups of people, one with no evidence of previous infection and the other with evidence of past infection. It concluded that past infection reduces the chances of catching the virus again by 83% for *at least five months*.”

3) 83% protection via natural infection isn’t foolproof against reinfection at all. Would you assume you’re invincible with those odds?

Another reason chasing herd immunity isn’t as good as vaccines.

4) “"The findings suggest that re-infection rates in the positive cohort were 83% lower than the negative cohort during the follow-up period."

But researchers warned that the protection was not total and that it was unclear how long any immunity lasts.

5) “We now know that most of those who have had the virus, and developed antibodies, are protected from reinfection, but this is not total and we do not yet know how long protection lasts," Susan Hopkins, senior medical adviser at PHE and co-leader of the study

6) “It is also possible that those who have a degree of immunity against the virus may still be able to transmit it to others.

7) “Even if you believe you already had the disease and are protected, you can be reassured it is highly unlikely you will develop severe infections. But there is still a risk you could acquire an infection and transmit (it) to others," Hopkins said.

8) Hopkins emphasized the point during an interview with the BBC's Today program on Thursday.
"[Infection] reduces your risk by at least 80%....but it doesn't eliminate it," she said.

9) "We found people with very high amounts of virus in their nose and throat swabs, that would easily be in the range which would cause levels of transmission to other individuals."

➡️people who previously caught Covid still need to obey distancing rules to avoid transmitting.

10) Also, as noted by @adamhamdy, the study period runs to the end of October when UK prevalence was relatively low before the recent wave and new variants.