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Michael Mina Profile picture
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8 Feb, 5 tweets, 2 min read
The new variant B.1.351 is evading immunity, infecting ppl already vaccinated w AZ vaccine

I’m concerned for the others too since all have very similar design against original Spike

This should be a wake up call

#Rapidtests needed for contingency plans

nytimes.com/2021/02/07/wor…
Good thing is the mRNA vaccines provided exceptional efficacy. But that was also when plasmablasts (temporary antibody producing cells) were fully abundant. We don’t know the efficacy after a few months after they all die off. Hopefully will remain very high and protect. But..???
We also do not know (or at least so far I haven’t heard) whether people are getting severely ill or not. If the AZ vaccine prevents severe disease w the new variant, then that can be good enough. I wish this part was reported so far.
Per others comments (thank you), the studies were not powered to look at all at severe diseases. Not surprising given the very small numbers of mild/moderate in both arms.
Terrific thread by @VirusesImmunity on this topic. Do read!

Though all with very small numbers, efficacy to reduce severe disease (vs. mild/moderate) appears to be very high.

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More from @michaelmina_lab

Michael Mina Profile picture
4 Feb
Short thread:

Cases are starting to plummet quickly.

This isn’t from vaccines (yet).

Possible we may be starting see a combination of seasonality on our side and likely seeing herd effects kick in.

1/x
On seasonality:

We knew in the summer that this virus was going to roar back in the fall. It did!

While coronaviruses collectively have a broad window each year, We can see that each individual coronavirus in the graph 👆has only a few months when it peaks. And then drops

2/x
This virus started really hitting us hard a second time in November. Oct-Jan may well be this viruses peak transmission window. We could be entering a reprieve from its grasp, at least for a while. If so, could help us get vaccines out and control spread quickly.

3/x
Read 10 tweets
Michael Mina Profile picture
1 Feb
NOTE:

If you see papers/media that show very low sensitivity for rapid Ag tests (i.e. 30%-60% sensitivity) the report is most likely making a common mistake:

Comparing a test meant to detect viable virus to a test that can detect minuscule amounts of RNA is a mistake.

1/x
PCR RNA stays around long after live virus is cleared

So if you see a paper that shows very low sensitivity, ask:

"Are they comparing rapid antigen tests to "anytime" PCR RNA positivity? (Especially studies asking about sensitivity among asymptomatics)

2/x
To interpret this, you should know that only 25%-40% of the time someone is PCR positive are they infectious w live virus.

So... even a test that is 100% sensitive for live virus should only show a 25%-40% sensitivity against PCR among asymptomatic people.

3/x
Read 9 tweets
Michael Mina Profile picture
28 Jan
Important: on the resurgence of SARS-CoV-2 in a place where herd immunity was already attained.

The authors lay out 4 reasons:

1) didn’t actually attain herd immunity
2) waning immunity
3) new strains evading immunity
4) much more transmissible strains

thelancet.com/journals/lance…
Waning immunity is likely as a component. The immune system memory is just like real memory. I needs to be exercised w repetition - like studying for a test. A single event will not likely offer life long immunity.

2/x
My real concern is mutation that will evade, even If partial our immune responses to earlier versions of the virus or to vaccines being made (which are directed specifically towards mimicking earlier versions)

We have to act now on slowing spread in this case w/out immunity

3/x
Read 4 tweets
Michael Mina Profile picture
24 Jan
Short🧵 On mutant strains emerging:

It’s a new virus - not in an optimal state upon “birth” as it leaped into humans.

Has so much room to grow and ‘learn’

Increases in transmission rates and evasion of immunity should be expected.

We can anticipate and act accordingly.

1/x
We can start now to think through new vaccine designs that are not all narrow number of epitopes (in this case single [important] protein) and essentially identical to each other.

We can start “future proofing” our vaccine design choices to reduce immense risk of escape.

2/x
We can also immediately start building an Arsenal of contingency plans.

Tools that will not be susceptible to the same risk of mutants escaping immunity that arise from the ecological pressures from vaccines and infections....

3/x
Read 6 tweets
Michael Mina Profile picture
19 Jan
Rapid Antigen tests for #COVID19 in UK are working!

Purpose is to rapidly identify infectious people - that is exactly what they are doing!

And doing it very well!

With an R=1.4, those 37000 would have otherwise become >100,000 in weeks.

1/x
thisislocallondon.co.uk/news/national/…
In the article, Jon Deeks, derides the tests saying the tests:

"missed 60% of the cases which would have been picked up by PCR" - Jon Deeks

YES! This is a good thing!

MOST time someone is PCR+, they are No Longer Infectious! Rapid tests are catching the infectious only!

2/x
This issue is mentioned above continues to plague people's understanding of rapid tests

The tests are different

Rapid Antigen Tests are BETTER than PCR at being specific for infectious virus

A public health test should not pick up people after they are infectious

3/x
Read 7 tweets
Michael Mina Profile picture
15 Jan
Apparently I cannot say this loudly enough

The recent @bmj_latest articles by @deeksj et al deriding Rapid Ag Innova Tests are simply WRONG

They simply do NOT appropriately interpret Ct values & do NOT consider massive importance of how long PCR remains + post-infectiousness
Inspection of Ct values among the Asymptomatics & correlation to RNA copies / ml shows Ct values in Liverpool are ~8 lower than often seen in literature. The failure to recognize this means the estimates of Ag test sensitivity for "high virus" are totally off.

2/x
The sensitivity for "moderately high" or "high" viral loads in the Liverpool data are ~90% and ~100%.

But to know this you cannot just assume a Ct of 25 elsewhere (often described as entering "high viral load") means same thing as a Ct value in other labs.

3/x
Read 9 tweets

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