再感染の危険性: ずくなしの冷や水

2020年10月16日

再感染の危険性

※ Dr. Safa Mote@SafaMote氏の2020/10/15のツイート
Yesterday, @nytimes published an article titled "Coronavirus Reinfections Are Real but Very, Very Rare."
I wish this statement were true. But it is not only inaccurate, it may lead to dangerous outcomes.
I will explain why in the thread below.

https://nytimes.com/2020/10/13/health/coronavirus-reinfection.html

※ Dr. Safa Mote@SafaMote氏の2020/10/15のツイート
1. For a case to be officially reported as reinfection, the current standard requires obtaining distinct genomic sequences of the virus for the first and second infections.

But genomic sequencing is expensive and therefore is not usually conducted for viral samples. 1/

2. The percentage of people who have been confirmed as infected is still very low, e.g., about 8M/330M = 2.4% in the US.

Assuming independence of the two instances of infection, the probability that someone in the US has been infected twice is 0.024 × 0.024 = 0.00058.  2/

3. Many patients did not even get a PCR test during the initial wave. So, we have missed many cases between January 2020 and May 2020. 3/

4. If the infecting viral load is not too high, many reinfections tend to be milder since the acquired immune response from a first infection seems to last for a few months.

So, many reinfections are either not detected b/c asymptomatic, or not reported & tested b/c mild. 4/

5. Finally, this virus has been with us for only ~ 10 months. Since there is some degree of innate immunity (due to infection) which may last for a few months, not enough time has passed to allow for many reinfections. 5/

6. There have been many anecdotal reports of reinfection in the news and on social media.
@BNODesk tracks officially reported cases of reinfection. Only some of them have already been published in peer-reviewed publications.

https://bnonews.com/index.php/2020/08/covid-19-reinfection-tracker/  6/

7. Why do I believe stating "reinfections are very very rare" without definitive proof is dangerous?

A. It is against the Precautionary Principle.

https://twitter.com/SafaMote/status/1300131603260334081?s=20 7/

B. It can encourage risky behavior by recovered patients, which might lead to their reinfection.

For example, they might decide not to wear a mask or have close contacts with other infected people, because they believe they cannot be reinfected.  8/

9. Even patients who have recovered from a prior infection might become severely sick or die if exposed to a large viral load. 9/

C. Reinfected patients can infect other susceptible people and fuel the chain of transmission even further. 10/

D. The outcome of COVID is not just death vs recovery.

COVID may lead to permanent damage in major body organs such as heart, brain, lungs, kidneys.

Also, many patients are suffering from Long Covid.

(Article by @edyong209)
https://theatlantic.com/health/archive/2020/08/long-haulers-covid-19-recognition-support-groups-symptoms/615382/  11/

As immunologists such as @VirusesImmunity & @RMedzhitov
have explained, I will remain optimistic for a vaccine, since vaccine immunity and innate immunity (i.e., due to infection) can be different.

https://nytimes.com/2020/07/31/opinion/coronavirus-antibodies-immunity.html 12/

But until a safe, effective vaccine becomes available, I strongly recommend wearing a FACE MASK and following Japan's 3 C's rule.

13/end


Dr. Safa Mote@SafaMote氏の2020/10/15のツイート
返信先: @fbear2014さん
Great question. As immunologists such as @VirusesImmunity & @RMedzhitov have explained, innate immunity acquired through infection is not necessarily the same as the immunity induced by a vaccine.
posted by ZUKUNASHI at 14:03| Comment(0) | Covid19
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