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14% reinfection rate? - magnus - 03-24-2020

According to this Asian news site,  China has reinfection rates of 14%

https://www.scmp.com/news/china/society/article/3076484/should-china-count-recovered-coronavirus-patients-who-test

Number may be smaller as some who test positive again might have never fully cleared the virus in the first place. 

Still, 10% reinfection would likely still throw a brobdingnagian wrench in the herd immunity strategy,  right?

RE: 14% reinfection rate? - burger - 03-24-2020

I believe that most doctors/epidemiologists who've looked at this don't think reinfection is happening.  The immune system makes antibodies to the virus, and most infections resolve that way.  Once that happens, you can't get reinfected to the point of being sick again for some time.  That time is unknown but should be months at least, if not years.  I don't believe that there are any confirmed cases of someone having symptoms, recovering, and then getting symptoms again.  The PCR test for the virus is very sensitive, and if there is still virus RNA around, the test may pick it up.

RE: 14% reinfection rate? - BostonCard - 03-24-2020

Generally, I agree with the assessment that in most cases reinfection should not happen for most patients (those with certain immune defficiencies may be vulnerable).  However, I want to caution that this virus has already confounded a lot of assumptions.  For example, the initial assessment was that asymptomatic (and presymptomatic) transmission was unlikely; we now know that's not the case.  And it is worth noting that the virus is an RNA virus like influenza, and RNA viruses are more prone to mutations than DNA viruses.  It is possible, though unlikely, that the virus will mutate and that it may become possible to be reinfected with a second strain.

The virus is challenging a lot of accepted wisdom about viruses.  Another exampole, it is generally believed that viruses that start out zoonotically (ie animal to human) are not very efficient at human to human transmission because the virus has not yet evolved for efficient human-to-human transmission.  That may have affected the initial Chinese response to the virus, where it was believed that if they just shut down the market that would be enough to prevent future transmissions.  But as we now know, that assumption was wrong.

BC

RE: 14% reinfection rate? - Goose - 03-24-2020

(03-24-2020, 09:41 AM)BostonCard Wrote:  Generally, I agree with the assessment that in most cases reinfection should not happen for most patients (those with certain immune defficiencies may be vulnerable).  However, I want to caution that this virus has already confounded a lot of assumptions.  For example, the initial assessment was that asymptomatic (and presymptomatic) transmission was unlikely; we now know that's not the case.  And it is worth noting that the virus is an RNA virus like influenza, and RNA viruses are more prone to mutations than DNA viruses.  It is possible, though unlikely, that the virus will mutate and that it may become possible to be reinfected with a second strain.
I think it is very important to keep the above in mind. This is a novel virus. You can infer behavior from other similar virus, but if you do so you must be aware that you may be wrong. Until we have the data, we don't know. Getting data takes time and research. One must trade off the damage of taking the time required to be certain against the damage of being wrong. Not always clear or easy.

RE: 14% reinfection rate? - fullmetal - 03-24-2020

I read a similar article during Wuhan's crisis, and it seemed that it was 14% who tested positive for the presence of viral RNA after symptoms had cleared up.  I'm not sure that necessarily means reinfection.  There have been very rare cases of "recovered" patients who subsequently died...but I haven't read about a case like that since two weeks ago.

RE: 14% reinfection rate? - magnus - 04-30-2020

Looks like in South Korea where there were people that tested positive after recovering, the positives were false positives

https://www.businessinsider.com/coronavirus-south-korean-reactivated-cases-not-reinfected-experts-2020-4

Apparently, the PCR tests were flagging dead virus.

RE: 14% reinfection rate? - magnus - 05-16-2020

Uh oh.

13 sailors who initially tested positive,  quarantined,  tested negative twice,  and returned to the ship,  have now tested positive again... after showing symptoms!

https://www.politico.com/news/2020/05/16/uss-theodore-roosevelt-sailors-test-positive-coronavirus-261873

Quote:Thirteen sailors aboard the aircraft carrier USS Theodore Roosevelt have tested positive again for Covid-19 after recovering from the disease and returning to the ship, which has been stranded in Guam since late March after an outbreak of the virus, according to two U.S. defense officials.

The Roosevelt's crew began returning to the ship in late April after spending a month either in quarantine or isolation in Guam. But sailors in early May began showing symptoms of the virus, such as a cough and fever, despite testing negative twice.

Some of the sailors who returned to the ship showed expanded symptoms, including body aches and headaches, according to one official. This has slowed the move back onto the ship, as all sailors who return must have been symptom-free for three days and have tested negative twice, as well as completed their isolation period.

Hopefully there's a good explanation for this.  Otherwise,  it bodes poorly for a back to normal endgame.

RE: 14% reinfection rate? - OutsiderFan - 05-17-2020

I had to LOL when I saw "and one tested positive for Tuberculosis."

It's not laughter from a hilarious joke, but just the absurdity of how much money we spend on all our defense apparatus and we can't even have infection control to stop infectious disease from rampaging through navy vessels?

TB is one of the most infectious diseases there is, even more than Covid.

RE: 14% reinfection rate? - Maple Leaf - 05-17-2020

(03-24-2020, 09:41 AM)BostonCard Wrote:  Generally, I agree with the assessment that in most cases reinfection should not happen for most patients (those with certain immune defficiencies may be vulnerable).  However, I want to caution that this virus has already confounded a lot of assumptions.  For example, the initial assessment was that asymptomatic (and presymptomatic) transmission was unlikely; we now know that's not the case.  And it is worth noting that the virus is an RNA virus like influenza, and RNA viruses are more prone to mutations than DNA viruses.  It is possible, though unlikely, that the virus will mutate and that it may become possible to be reinfected with a second strain.

The virus is challenging a lot of accepted wisdom about viruses.  Another exampole, it is generally believed that viruses that start out zoonotically (ie animal to human) are not very efficient at human to human transmission because the virus has not yet evolved for efficient human-to-human transmission.  That may have affected the initial Chinese response to the virus, where it was believed that if they just shut down the market that would be enough to prevent future transmissions.  But as we now know, that assumption was wrong.

BC

+1  "The virus is challenging a lot of accepted wisdom about viruses" and this adds to the difficulty of developing drugs that can either prevent transmission or treat those who become infected.

RE: 14% reinfection rate? - BostonCard - 05-17-2020

(05-17-2020, 09:00 AM)OutsiderFan Wrote:  I had to LOL when I saw "and one tested positive for Tuberculosis."



It's not laughter from a hilarious joke, but just the absurdity of how much money we spend on all our defense apparatus and we can't even have infection control to stop infectious disease from rampaging through navy vessels?



TB is one of the most infectious diseases there is, even more than Covid.

My last trip before the shutdown, in mid-February was on a medical mission to Honduras.  While there, I diagnosed a patient with tuberculosis, though not until after he had entered my exam room and exposed me.  Ironically, at the height of COVID-19 pandemic, I thought if I developed a fever and cough, it was more likely to be due to TB than COVID-19.  Because of the pandemic, I still haven't been tested to see if I have a latent TB infection (since I am pretty asymptomatic, it is unlikely I have active TB, though you never know).

TB is a different challenge than COVID-19.  Yes, it is very infectious, in part because patients with active TB will be sick for a long time (the guy I diagnosed told me of over six months worth of fevers, cough, and weight loss) and though treatments for TB are available and effective, it takes a long time (6+ months) to treat it successfully.  It is also known to be spread by aerosols, so I would have needed an N95 to protect myself. The bacteria can also develop resistance to TB drugs, which is a problem for people who don't take the entire treatment course.  Annually, TB kills 1.5 million people, which is about 5 times as many people as have died from COVID-19 to date.  The upshot, though, is that it is treatable, and even if untreated, most people will successfully fight off the bacterium, though they won't completely eliminate it.  In most patients, the bacterium will never reactivate, and even if untreated they will not develop active TB 90 - 95% of the time.  But especially in patients with immunosuppression (like HIV/AIDS), certain lung diseases, certain exposures (for example coal miners), or those taking certain medications (for example TNF inhibitors for rheumatoid arthritis), the disease can reactivate and the patient will become infectious.

BC

RE: 14% reinfection rate? - fullmetal - 05-18-2020

They're probably just showing signs of successfully fighting off a second infection, as the positive tests were likely genomic tests.