Thread by @AmmarRashidT

Imran Khan, Asad Umar & Insafians keep making a fundamental mistake about the entire purpose of lockdowns and social distancing, which is clearly sabotaging Pakistan's entire covid-19 response. This urgently needs to be rectified. A thread.

IK keeps repeating this talking point - like in this video - that the purpose of lockdowns is to buy time until a vaccine is developed, which will be far too long to afford. This is absolutely not the case.

Lockdowns are a measure to enforce social distancing, which is a non-pharmaceutical intervention (NPI) to contain infectious disease. The epidemiological purpose of social distancing has nothing to do with vaccines - it is to reduce the Reproduction number (R0) to around 1.

The R0 is an indication of the transmissibility of the virus and denotes the average number of people one primary infected individual transmits the virus to. It is different for each virus. The avg R0 for covid-19 (without distancing) has been found to be slightly above 3.

In a basic model of social distancing, when a proportion “f” of the population decreases their interpersonal contacts to a fraction “a” of their normal contacts, the effective reproduction number R is given by:

R = [ 1 - (1 - a²) f ] R0

If R can be kept below 1 for long enough (usually a few weeks) via social distancing, testing, quarantine & contact tracing, the number of new infections begin to decrease and containment is achieved. This is what dozens of countries around the world did before easing lockdowns.

This is the key variable most countries around the world have monitored as they imposed lockdowns & other NPIs for social distancing. It is when the R0 goes below 1 (eg, every infected person infecting <1 person) that infections start going down & restrictions can be eased.

When Imran Khan says its inevitable that cases & deaths will just keep increasing, that is a lie. Dozens of countries (many of them poor) have managed to bring down their R0 & bring new cases to a trickle (and keep them low!). Many others are on their way there. Pakistan is not.

Our neighbors like India have also been monitoring their R0, for the country & each state, to determine where restrictions can be eased or not. So for eg, you can see how the R0 was flucutating b/w 3 & 2 before lockdown & gradually edged close to 1.

science.thewire.in/the-sciences/b…

The most recent ease in the Indian lockdown was determined after the disovery that the R0 was steady at 1.23. Not enough for containment but low enough to not cause exponential growth either.
theprint.in/health/indias-…

Now to the worrying part - in Pakistan, our policymakers have never even mentioned the R0 at a single briefing. It actually seems as if they don't know about it or haven't calculated it - everyone from IK to Asad Umar to Zafar Mirza only mention cases, deaths & health capacity.

I checked with friends in WHO/HealthMin & they said the Health Services Academy calculated it sometime in April (somewhere b/w 2 and 3) but it wasn't being monitored & not part of NCOC briefings. Pakistan does not appear to be tracking R0 - the main goal of social distancing.

This explains why PTI's entire response is so jumbled. They seem to believe the main measure that can contain the virus - social distancing - is only meant to be imposed when the health system is close to complete collapse. This is what Asad Umar said about lockdowns *today*.

This has also severely undermined the communication effort, by repeatedly telling the public lockdowns are only to buy time till a vaccine in the uncertain future. Unlike other world leaders, IK never explained it as a time-bound measure with a goal to encourage compliance.

Whenever he talks abt other countries, IK also repeats the lie that whenever lockdowns are lifted after flattening the curve, cases have spiked back to the same levels. This is also false. Most countries that flatten the curve manage to keep it there through continued TTQ.

In sum:
1) The PTI govt doesnt understand what the whole point of lockdowns/social distancing is.
2) The point isnt to impose them till a vaccine but to reduce R<1
3) If R<1 for a sufficient period of time via contact reduction, cases will go down & the virus will be contained

4) The PTI govt doesn't seem to be tracking R & no one in the media or opposition asks them about it.
5) The top-down confusion about the point of lockdowns/distancing has reduced public support for it as most have been conditioned to think of it as an indefinite imposition.

6) We do have to 'live with the virus'. But that doesn't have to mean killing 1000s daily. We must *properly* enforce social distancing for some weeks, bring the R<1 so new infections fall & then ease. After that we can 'live with it' & maintain surveillance via TTQ. The End.

Finally a govt official is asked about R0 in the media. And Dr. Mirza's hesitant answer makes it quite clear why the govt wasn't keen on sharing it with the public. "It had reached around 2.. I don't remember the exact figure.. but it has grown.." This is pretty grim.

For the record, I don't think Dr. Mirza hesitated here because he wasn't sure about R0. I think he was worrying abt the consequences of sharing the reality of a rising R0, which would provide an empirical basis to contradict the PM's 'vision' for the pandemic (reopen everything).