UK has authorized AZ/Oxford vaccine.

Importantly: UK is leading the way in taking a bold public health approach (vs individual health) to getting the population vaccinated - Prioritizing distribution of 1 dose & delaying dose 2 up to 12 weeks.

This bold move is going to cause ppl to scrutinize the decision. But in this pandemic, too few governments have acted swiftly to limit spread - bc quick action sometimes means imperfect data.

Here, robust data isn’t likely available for a 12 week delay for dose 2


This was a good decision that

a) need not be permanent and suggests the UKG is willing to think with agility here and

b) likely will be the better overall public health approach rather than letting doses sit in freezers while others die and


c) this experience in next 2-3 months will provide crucial information for the UK and the world that has the potential to provide massive benefits in terms of (i) speed to achieve herd immunity across populations and (ii) get entire extra countries vaccinated in 2021.

I commend the UK Gov for taking a bold step toward recognizing the gravity of the problem, weighing the available data against the potential benefits and making a decision grounded in optimizing public public gains over individual health gains. The distinction is crucial.

Could the program backfire? Maybe. Is it likely to? No.

The boosters will be given by 12 wks. For this to be worse than letting doses sit in freezers, the vaccine would have to essentially lose all benefits during months 2 and 3 and ability to boost at 8-12 weeks. Very unlikely
Regarding efficacy concerns

Say, you take pop that received single dose, and ask “how bad would efficacy need to be to be worse than alternative”

If alternative 2 dose regimen is 90% efficacy, then pop eff would be 45% (50% vaccinated).

So, months 2/3 post dose 1 must be >45%
If we convert public health thinking in this case into a closer to home medical dilemma, this is sort of the question faced when making this decision of spacing the vaccines to 12 weeks instead of 4 given imperfect data 👇
With @zeynep we wrote about the need to think critically about these questions of single dose vs two dose vaccines to optimize public health effectiveness, particularly given how good the (very limited) signal after single dose of mRNA vaccines…
And here is data for a single dose AZ vaccine which looks essentially as good as two doses through 150 days.

Further supporting this decision.

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More from @michaelmina_lab

31 Dec 20
Dec 31 2020

Out-of-control spread of SARS-CoV2

Nearly 4000 #COVID19 deaths per day in US

Vacc are many months away for most ppl

Rapid paper strip tests *could* be in everyone’s home today to curb spread immediately

Write to your congress ppl and demand they be a priority

We make it easy for you to do this and have collected signatures from leading scientists requesting congress act on these - Set aside funds that amount to <1% of the most recent stimulus bill to get these tests to everyone, quickly and for months.
FDA / others think the populous is not capable of having simple tests at home & making responsible decisions

This is insane - plus we have expensive over the counter tests that require much technology - so I guess FDA feels the wealthy can use their own data but poor cannot. BS!
Read 5 tweets
31 Dec 20
Great article bc it feels a bit haphazard (by intention) and thus captures the confusion of the current status of vaccine rollouts across the world.

But I want to talk about a specific quote in the article...

Many scientists have been frustrated that UK extended time between vaccine doses to ~12 weeks - in effort to get as many people as possible at least a single dose.

This makes sense for optimizing public health. But for optimizing individual protection it is controversial.

One scientist in the article said:

“I wouldn't want to be sitting around for 12 weeks waiting for the second dose with the partially protective vaccine,”

Under normal optimal circumstances, this opinion might be the right opinion, but In midst of a pandemic, it is faulty..

Read 13 tweets
30 Dec 20

If a public health goal is detecting infectious ppl:

The most sensitive #COVID19 test in the world, if used rarely (ie 1x/month) is:

much LESS sensitive and LESS effective than a low sensitivity test used frequently.


If a very sensitive #COVID19 test has a 24 hour or more delay to return results, it quickly becomes:

LESS EFFECTIVE to stop spread of SARS-CoV-2 than a lower sensitivity test that gives results in minutes.

These are simple concepts when we start to look at testing not as a clinical diagnostic use, but for public health use to slow spread.

We discuss this here:

Read 5 tweets
26 Dec 20

Data from Birmingham garnered LOTs of negative press about #COVID19 rapid Ag tests

The data

1) is very small, 8 positives
2) Shows EXACTLY what we expect, Rapid Ag tests detect infectious ppl, not super low PCR RNA

Overall, the conclusions IMO SUPPORT rapid tests

We know that high PCR Ct values (very low RNA) above 30 are generally not culturable/not likely contagious

For context, a Ct value of 30 is ~99.999% lower RNA than peak RNA when most contagious.

The Rapid tests in the study appear to have a limit of ~30

So, even when virus is culturable at Ct 30, it is much lower amt than peak virus titers/when most transmissible.

Plus, Missing a Ct of 30+ is most likely missing someone AFTER peak viral load and not before Bc the time spent around 30-35 is much longer after than before.

Read 7 tweets
26 Dec 20
I feel frustrated to see me and my peers getting vaccinated ahead of essentially every high risk person on Earth.

We are generally low risk, have access to incredible healthcare, are mostly in upper echelons of wealth.

Incredible inequities.
Our systems are so broken.
When we proposed single dose vaccine trials - peers said it is unethical to give just single dose since we don’t know how it will work, in middle of pandemic

Unethical?? Ethics are global. Giving vaccines to the wealthiest, w access to PPE and least vulnerable first is unethical
(I did not actually sign up for my vaccine. But I could get it any time. Out of principle I will not get vaccinated first in line. It is not right for me to do so)
Read 6 tweets
24 Dec 20

There is (rightly) concern about the variant SARS-CoV-2 strains. I want to talk about what this means for vaccines, our future, and why we MUST have contingency plans.

This thread is in response to many questions I've received.

First, Note: I'm not doing a deep dive on specific mutations. For that, see @angie_rasmussen @jbloom_lab @K_G_Andersen @BillHanage. I am an infectious disease immunologist / epidemiologist & study viruses/vaccines. So I'll speak from that perspective.

Second Note: I do not want this thread to be alarmist.

To put it upfront, the mutations thus far do not indicate a major evasion of immunity interfering w vaccines. However, the mutations should be a wake up call to action.

Read 26 tweets

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