First case of documented #COVID19 reinfection. Second infection (asymptomatic-with elevated CRP) 142d later, by a genetically different #SARSCoV2 strain.
Implications:
- As in other coronaviruses, reinfection possible.
- Immunity from 1st may have led to milder 2nd episode?
... https://twitter.com/ABsteward/status/1298287856063000576

- vaccine trials should also include persons wt past COVID19.
- low antibody titres in 2nd episode might mean that seroprevalence studies underestimate?
- viral cultures pending to see Neutralizing antibodies in both episodes.

Still, actual frequency of re-infection remains low and unknown (only 8 months in the pandemic), therefore future implications remain to be seen

Nice thread of thoughts on the recently published case of #SARSCoV2 reinfection https://twitter.com/kakape/status/1298038827265687558?s=19

Second case of #SARSCOV2 reinfection (pre-print):
25yo, 2 episodes from genetically different strains, 48d apart
What’s different? 2nd episode was more severe (pneumonia & hypoxemia). Authors used a series of tests to confirm findings & rule out errors
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3681489
...

As time passes and spread continues, we're seeing more cases that are out of the norm. Currently, evidence is scarce, so estimates can't be safely made.
But if reinfection is common, then that’s probably good news, bc most must have gone undetected (asymptomatic or mild).
...

As with other coronaviruses (& other viruses), reinfection can’t be excluded. Here’s a great thread on re-infection with influenza & measles https://twitter.com/jbloom_lab/status/1299479311129300994 .
So let’s keep our calm while we still assess the extent of this phenomenon
...

I can only support that in the majority, subsequent episodes are milder due to built-up immunity (and this is perhaps why we haven’t already seen more).
Again, comes the need for widespread vaccination to reach herd immunity levels asap within a short time period.
...

There’s a lot we still don’t know on #SARSCoV2, especially immune mechanisms, immunity, clearance, genetic mutations & their clinical implications. For example:
- Does the level & extent of immune response during first episode affect the possibility of a second infection?
...

- Similarly, could there be variable protection due to variable immune responses elicited during an initial episode? (eg.antibodies produced during an infection that can’t protect from a genetically discordant strain)?
- Can a reinfected person transmit the virus?
...

Here’s a nice piece that explains reinfection and its possible implications https://www.statnews.com/2020/08/28/covid-19-reinfection-implications/