re: Americans testing for the hantavirus - UPDATE

What is actually being said:

“ “This is not COVID, this is not influenza,” infectious disease epidemiologist Maria DeJoseph Van Kerkhove said during a press conference.

Van Kerkhove noted several differences between COVID and hantavirus while speaking with reporters on Thursday. Namely, COVID-19 was a novel virus, or a strain we had not seen before. Hantavirus has been around “for quite a while,” Van Kerkhove said.”


What is being heard:


“MASK UP AND LYSOL EVERYTHING! MAGACASAR CLOSE YOUR BORDERS! WE NEED TO LOCK DOWN AND SHUT ALL THE THINGS! IF IT ONLY SAVES ONE LIFE ITS WORTH IT!”

Yes but the majority of cases wasn’t until later, after they refined the protocol, which to my knowledge included improved primer specificity and a ct cap of 30. You wouldn’t even run the test past 30. You were to declare it as negative.

So going back to the start of the chain, while I’m sure false positives existed, especially early, I doubt very very very that a significant portion of overall testing was a false positive. Especially not half.

You are misremembering. Covid was a thing to watch before it was a thing that happened. Lots of experts were watching it with trepidation in January. Even on this board, there were posts as early as December '19 about a weird pneumonia-like thing going around parts of China.

quote:

---

Yes but the majority of cases wasn’t until later, after they refined the protocol, which to my knowledge included improved primer specificity and a ct cap of 30. You wouldn’t even run the test past 30. You were to declare it as negative.

So going back to the start of the chain, while I’m sure false positives existed, especially early, I doubt very very very that a significant portion of overall testing was a false positive. Especially not half

---

My comment specifically mentioned tests in the US from March 2020 thru the fall of 2020 resulting in positives with too high of a CT with many not saving the CT results to relook at those results from March thru the fall of 2020 to subtract any positive with a CT above 33 at the time.

It may be 30 now, but back then I remember 30 being proposed by some to ensure positive tests had live virus as 31 thru 33 would trigger positive for the live virus but still some partial fragments. Some pushed 35 to make sure no actual positives were missed regardless of some positives being dead fragments. With many still using tests into the fall of 2020 that were previously received or purchased I am not really know when most or all positive test results would haven been with 30 or 35 as the cycle threshold.

I agree false positives did not make up half of all positives thru the fall of 2020, but since many places didnt even store their CT numbers and just stored whether it was positive or negative the exact amount is impossible to ever find out.

It was still relatively high, and in the US a lot of hysteria, affects on elections, continued full shutdowns (or acceptance of them), and online learning (maybe online learing fits better) were caused by all the positive results reported from March 2020 thru the fall of 2020.

I get using 40 initially (some used 37 which was still too high), but I don’t get not including the CT with the positive results initially.

From August 2020 NY Times article with limited sample size due to limited access to CT data.

quote:

---

Your Coronavirus Test Is Positive.
Maybe It Shouldn’t Be.

The usual diagnostic tests may simply be too sensitive and too slow to contain the spread of the virus.
By Apoorva Mandavilli

Tests authorized by the F.D.A. provide only a yes-no answer to infection, and will identify as positive
patients with low amounts of virus in their bodies. Johnny Milano for The New York Times

The PCR test amplifies genetic matter from the virus in cycles; the fewer cycles required, the greater the amount of virus, or viral load, in the sample. The greater the viral load, the more likely the patient is to
be contagious.

This number of amplification cycles needed to find the virus, called the cycle threshold, is never included in the results sent to doctors and coronavirus patients, although it could tell them how infectious the patients are.

In three sets of testing data that include cycle thresholds, compiled by officials in Massachusetts, New York and Nevada, up to 90 percent of people testing positive carried barely any virus, a review by The Times found.

…Officials at the Wadsworth Center, New York’s state lab, have access to C.T. values from tests they have processed, and analyzed their numbers at The Times’s request.

In July, the lab identified 794 positive tests, based on a threshold of 40 cycles. With a cutoff of 35, about half of those tests would no longer qualify as positive. About 70 percent would no longer be judged positive if the cycles were limited to 30.

In Massachusetts, from 85 to 90 percent of people who tested positive in July with a cycle threshold of 40 would have been deemed negative if the threshold were 30 cycles, Dr. Mina said. “I would say that none of those people should be contact-traced, not one,” he said.

Other experts informed of these numbers were stunned.

“I’m really shocked that it could be that high — the proportion of people with high C.T. value results,” said Dr. Ashish Jha, director of the Harvard Global Health Institute. “Boy, does it really change the way we need to be thinking about testing.”

---

quote:

---

Points raised in NY Times article
• Standard tests diagnose large numbers of people carrying insignificant
amounts of virus.
• Most are not likely to be contagious. If Ct >33, virus not grown in culture.
• A cycle threshold >35 is too sensitive.
• A more reasonable cutoff is Ct 30-35 or even Ct <30.
• In NY state lab, 50% of recent positives had Ct >35.
• In MA, 85-90% of positives in July had Ct >30.
• Cycle threshold is never included in the results sent to clinicians.
• For outbreak tracing, cheap and abundant rapid tests are needed, even if less sensitive.

---