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Michael Mina Profile picture
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3 Nov, 5 tweets, 2 min read
NEW terrific study on rapid tests

The importance of this figure canNOT be overstated!

Rapid tests caught 80% of PCR positives but all missed had very low viral loads

Thus, as expected it will successfully capture ppl most likely to be contagious

1/
medrxiv.org/content/10.110…
The specificity of the PanBio, BinaxNow and SD Biosensor tests (the three leading manufactured rapid tests in the world) are looking very good!

In this paper, specificity was 100% in >400 samples... thus >99.2%

Now multiple studies showing very high specificity!

2/
The sensitivity metrics AND specificity metrics are now completely in alignment with what we have proposed for frequent rapid testing that can control outbreaks without vaccines.

medrxiv.org/content/10.110…

3/
Also this paper here:

nejm.org/doi/full/10.10…
Also note that in this study the Ct values are Very low on average. This drives home the message that Ct values must be calibrated per lab and per test. These are, overall, lower by 5 Ct values or so from other labs. Thus we can compare Cts but must take care to do it correctly.

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More from @michaelmina_lab

Michael Mina Profile picture
5 Nov
A new article in ⁦@nytimes⁩ states rapid tests falter in asymptomatics

Warning of their use for asymptomatic screening

Says: among random asymptomatic #COVID19 screens, Rapid Tests caught only 32% of PCR +ve people

This is misleading...

1/
nytimes.com/2020/11/02/hea…
Tests have to be matched to their purpose. If doing asymptomatic screening - you are looking for INFECTIOUS people.

Importantly, MOST (~70%+) of the time someone is PCR +ve, they are POST-infectious!

2/ Image
Since antigen tests meant to detect viable/live virus, we only EXPECT them to be positive about 30% of the time of PCR

Thus, finding 32% of positive PCR tests in random asymptomatic screening is absolutely the EXPECTED result for a test looking for infectious people

3/
Read 13 tweets
Michael Mina Profile picture
3 Nov
Can contact tracing work for #COVID19?

Much effort assumes contact tracing works for COVID - surveillance testing assumes so

I’ve had major concerns - this paper reinforces it.

For fast pandemics, we cant act only on what has been successful before

1/
jamanetwork.com/journals/jamai…
In this paper, 791 #COVID19 positive people were contact traced AND universal testing was recommended for their close contacts.

Ultimately only 120 people were discovered.

2/
If COVID has an R of ~1.3… those 791 people perhaps led to >1000 additional cases.

If 120 were discovered... ~900 were not.
And this was an organized operation.

3/
Read 13 tweets
Michael Mina Profile picture
29 Oct
In light of the recent article from the UK discussing antibody waning - it’s important to read additional reports that show that while the antibodies are waning, they are not disappearing. This is expected and the natural course of an immune response.

1/
After a primary infection, antibodies go sky high - along with the cells that produce them - and then after the virus clears, those cells must subside and the antibody production falls. Antibodies this wane, almost by definition, after a primary infection

2/
Importantly, the antibodies do go down and, like in the UK report may fall below the limit of detection. But like in the @SciImmunology paper above by @florian_krammer among others, when a more sensitive test is used, they often remain detectable...

3/
Read 10 tweets
Michael Mina Profile picture
28 Oct
New paper showing strong agreement between nasal (ie self collection) and nasopharyngeal swab on rapid test. This is an important finding since, in US, rapid tests currently authorized for nasopharyngeal swabs and thus need healthcare collections

1/ medrxiv.org/content/10.110…
These types of studies are needed to identify how well rapid antigen tests may work with self collected swab - essential for wide distribution and public health screening use of these tests to help curb outbreaks.

Other notable items from this paper:

2/
One is that the rapid antigen tests in this paper (SD Biosensor) performed very well up to a Ct of about 30. This is what we have expected for these tests and is likely at this rate to capture most infections with viable virus. Great for a public health screening test

3/
Read 8 tweets
Michael Mina Profile picture
27 Oct
Eli Lilly’s antibody therapy unfortunately is not working in hospitalized patients. A blow to a hopeful “remedy” that could help tip the balance between risk of infections vs risk of economic fallout

But this isn’t the last of this story.. not by far

1/
nytimes.com/live/2020/10/2…
First, there are other antibody based therapies that are being developed, are in trials and new versions in early R&D phase.

Monoclonal antibodies have a huge potential and we mustn’t let this get us down.

2/
Regeneron’s monoclonal antibody therapy for example (the drug given to the president) remains in trials for hospitalized patients. This is but one of many that will be in trials!

3/
Read 7 tweets
Michael Mina Profile picture
25 Oct
This is incredibly sad and bad news for the US.

In only 3 days, the 14-day average change in #COVID19 HOSPITALIZATIONS has skyrocketed from 7% to 15%!

This means hospitalizations are not simply increasing but accelerating upwards at a fast pace.

1/
For the 14 day average change to >double in only 3 days means that the actual current change is much more than 15% (to pull a 14-day change that far up in only 3 days means the past three days have seen remarkably large increases).

2/
This is not some fear tactic. This is peoples lives. This is the proper functioning of our healthcare system (already stretched to the brim at baseline).

We are only at the beginning of this “spike” and it could continue accelerating up for months!

3/
Read 6 tweets

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