Coronavirus - worldwide spread and control

[Jonathan Edwards]

UK govt admits that none of the 17.5 million tests they ordered, actually work.

Having had about forty years of experience of using antibody tests this comes as no surprise. The only interpretable tests are done in pairs two weeks apart using the same testing plate and a control. The next major debacle I suspect will be the realisation that nobody has been taking paired sera so even when a reliable test comes along most people who have had the virus cannot be reliably tested. The incompetence of what is going on would have horrified my mother if she were in a position to give an opinion.

 

[Barry]

Unfortunately the virus does not care too much whether the NHS can cope; the virus will continue on its own course. So it's only the maths that we can consider here.

The crucial figure in the maths is the time it takes for the death toll to double.

If you look the Worldometers death toll graph for Spain, which has been in lockdown since 14 March (so for 23 days), their death toll presently doubles every 7 days. So under lockdown conditions at present, they have a 7 day death doubling time.

7 days is close to the 6 day doubling time I assumed for the UK calculation.


Italy has been in lockdown a bit longer, since 9 March (so for 28 days), and the Worldometers graph shows that it currently has a 10-day death doubling time (whereas before the lockdown its death doubling time was 4 days). The longer doubling time (compared to Spain) likely reflects the longer time in lockdown.


So a lot depends on how effective the UK lockdown will be, and how this lockdown slows the death doubling time. The UK lockdown started on 23 March (so its been running for 14 days).

I still don't buy it Hip. Your estimate makes a simplistic extrapolation of something that will not be that simple.

To me the simple test is that if the whole UK population were to become infected within 6 weeks, then that could only happen if the virus were allowed to run its course. If a large proportion of the population are locked away to escape infections, then they cannot all become infected. Which means something is wrong with the maths and/or the assumptions behind the maths.

You cannot have it both ways: That the maths accounts for the lockdown and shows the whole UK population infected in 6 weeks, but at the same time if everyone is locked down then it will be impossible for everyone to be infected. As a sanity check it says something is wrong.

 

[lunarainbows]

A group of researchers in Oxford are now recruiting participants to their trial to find out what proportion of the population either has the virus, or has had the virus? Will these tests accurately detect whether someone has had it, unlike the UK govt’s approach so far? (I’m a bit confused on this).

“What type of tests are you doing?
In this study, we are comparing serology immunoassay, polymerase chain reaction (PCR) and nanopore sequencing diagnostic approaches. Serology requires a finger prick at-home blood test (which is then discarded), while the other two require throat swabs processed in the lab.

–Serology tests detect antibodies and may indicate whether someone is currently infected or has previously been infected.

–PCR tests can detect short sections of genetic material that are unique to a virus. This is currently a widely used diagnostic method.

–Nanopore technology sequences the entire genome of the virus through a small protein called a ‘nanopore.’ We are exploring whether this method, which doesn’t require knowledge about the pathogen beforehand, could be a diagnostic tool for new pathogens like COVID-19 that emerge.”

https://covidstudy.zoo.ox.ac.uk/#section1

 

[lunarainbows]

The only interpretable tests are done in pairs two weeks apart using the same testing plate and a control.

In the Oxford study (which I posted above), where they are trying to establish how much of the population has/has had the virus, it also says:

“What will I be asked to do?
We will be randomly selecting participants from those who apply to receive a kit. You will be contacted to let you know you have been selected, and provided a date of courier drop off and collection to your home.

You will be asked to read over all the instructions, read and sign the consent form, and complete a finger-prick test and self-collect two throat swabs. You will also be asked to complete an online questionnaire (preferred) or fill in the identical paper copy provided to you. You will be able to report the serology readout on your questionnaire after which the test strip can be safely discarded at home. The two throat swabs need to be returned for laboratory processing in the approved packaging provided. Couriers will pick up from your home on the date provided.“

It doesn’t look like any of the tests at Oxford are done in pairs two weeks apart. The serology is what they are saying will identify antibodies but that’s just a test strip. I don’t know what tests they are using, if the UK govt doesn’t have reliable tests yet?

 

[Jonathan Edwards]

A group of researchers in Oxford are now recruiting participants to their trial to find out what proportion of the population either has the virus, or has had the virus? Will these tests accurately detect whether someone has had it, unlike the UK govt’s approach so far? (I’m a bit confused on this).

This study looks like a non-starter. You cannot obtain a random sample by asking people to sign up via social media. From what you have quoted so far this looks completely amateur. This is the trouble these days, junior scientists with no basic training in clinical methodology think they can run meaningful studies without making use of common sense.

 

[alex3619]

So that's a total of around 6 weeks, at which point the pandemic will be over in the UK.

Isolation slows viral growth down, and by decreasing burden on the hospitals it improves survival. At peak infection the death rate may climb and approach 9% where it is in some countries.

Most of this reply follows on this point and its for the general readership.

This also ignores the second wave. There are now at least TWO Corona viruses. Soon there may be many more. However there may be additional partial immunity after each wave.

Some method of social isolation or hygiene may have to be in place for maybe even two years. Now this is NOT the high level of isolation we have now in many places. Once numbers are lower, and systems for testing and tracing are fully operational, the problem will be much easier to contain without stringent measures on the general population. Add in vaccination in possibly less than two years, plus some herd immunity, and things could be well under control, and the world heading for recovery.

Just don't expect this by mid-year.

Now we can turn this around in general by early in the second half of the year for those countries that still quarantine new arrivals and anyone who tests positive, with social isolation for close contacts of anyone who is positive, and a society-wide maintenance of increased hygiene standards. That means nearly everyone can return to work. That means we can have social events, but don't be surprised if many start wearing masks. Are masked dances and events due a comeback?

Once new numbers peak we can expect the numbers to fall dramatically. Once it is nearly gone we may have to remain vigilant for possibly two weeks. Then we can expect restrictions to be largely lifted, provided that travel to and from hotspots is prevented, or there is mandatory quarantine for everyone from hotspots. Currently in Australia travellers are being placed in quarantine hotels.

For any country still infected later this year, travellers from these hotspots may not be permitted to go to most of the world. Travel can be expected to be restricted, though I wonder how many governments will ignore this.

Most of the world may be back to something like normal long before the end of the year. It will vary country by country. Those countries that acted early will recover much sooner, those that still don't have a lockdown may still have issues at the end of the year. I expect those that did not do isolation, hygiene, testing and tracing will have a higher economic cost. We will see, and maybe learn some lessons. Economists will be closely watching this, and we may learn a lot about economic impact.

Every country needs a pandemic response system, which includes protective equipment and possibly ventilators.We knew this maybe twenty years ago, after multiple viral epidemics. We should have learned it following 1918 but sadly we didn't.

 

[Hutan]

Posts about an exploding whale carcass analogy have been moved to the Covid humour thread.

Posts about Boris Johnson's Covid-19 illness have been moved to the Well-known people with Covid-19 thread.

 

[Hip]

To me the simple test is that if the whole UK population were to become infected within 6 weeks, then that could only happen if the virus were allowed to run its course. If a large proportion of the population are locked away to escape infections, then they cannot all become infected. Which means something is wrong with the maths and/or the assumptions behind the maths.

You raise a good point. Thinking about what you said, perhaps it could be argued that we have two sub-populations co-existing in the same country: group one which are those still working, and thus are subject to a higher transmission rate; and group two which are locked down at home, and are therefore subject to a lower transmission rate.

So when we see the increasing numbers infected, those numbers may mostly be coming from group one. So it could be that group one quite quickly reaches near saturation point in terms of the numbers infected, but infection levels in group two remain lower.

Group one may thus develop the herd immunity, but group two may continue to be susceptible.

The point you raised is something that requires further thought.

Sorry, @Hip, but I think this is way off target. None of your assumptions look to me to be realistic.

There is likely to be a huge deceleration of the outbreak in the pipeline already from social distancing.

Well I hope I am wrong, because it will be horrendous if we get the tsunami of cases the above calc predicts.

In terms of whether the pandemic is slowing down due to lockdown, if we look at the data from Italy, who have had lockdown for 28 days, their death toll doubling time was about 4 days before lockdown was implemented, and is presently about 10 days. So there has been some slowdown, but not a great amount so far.

Whether they will continue to slow down or just stabilize at 10 days remains to be seen in the coming weeks.

Although we have to remember that the death toll data is just a snapshot of the situation as it was 17 days ago, because 17 days is the average time to death after catching the virus.



As for the published figures for the number infected, obviously these are off by a large factor because they are not testing everyone who gets the virus. But it seems like a wild guess to try to pin down this large factor.

That's why I think it might be better to calculate the number infected from the death rate, because these death rate figures I think are quite robust. The only problem with using the death rate is that you get this 17 day lag, so you have to use a formula like the one devised by Tomas Pueyo, to compensate for that lag and get an estimate of the actual number infected today.

 

[Snow Leopard]

Would anyone agree with my calculation that in the UK, this pandemic will be over in around 6 weeks' time?

Maybe, if the UK adopts strict quarantine (eg forced isolation in hotels) for all international travellers.

But I doubt (and hope not) that so many people will be infected that herd immunity will be achieved, instead, downtrending infection rates due to the various restrictions in place is the best way to move forward.

 

[Cheshire]

Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy

Importance In December 2019, a novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) emerged in China and has spread globally, creating a pandemic. Information about the clinical characteristics of infected patients who require intensive care is limited.

Objective To characterize patients with coronavirus disease 2019 (COVID-19) requiring treatment in an intensive care unit (ICU) in the Lombardy region of Italy.

Design, Setting, and Participants Retrospective case series of 1591 consecutive patients with laboratory-confirmed COVID-19 referred for ICU admission to the coordinator center (Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy) of the COVID-19 Lombardy ICU Network and treated at one of the ICUs of the 72 hospitals in this network between February 20 and March 18, 2020. Date of final follow-up was March 25, 2020.

Exposures SARS-CoV-2 infection confirmed by real-time reverse transcriptase–polymerase chain reaction (RT-PCR) assay of nasal and pharyngeal swabs.

Main Outcomes and Measures Demographic and clinical data were collected, including data on clinical management, respiratory failure, and patient mortality. Data were recorded by the coordinator center on an electronic worksheet during telephone calls by the staff of the COVID-19 Lombardy ICU Network.

Results Of the 1591 patients included in the study, the median (IQR) age was 63 (56-70) years and 1304 (82%) were male. Of the 1043 patients with available data, 709 (68%) had at least 1 comorbidity and 509 (49%) had hypertension. Among 1300 patients with available respiratory support data, 1287 (99% [95% CI, 98%-99%]) needed respiratory support, including 1150 (88% [95% CI, 87%-90%]) who received mechanical ventilation and 137 (11% [95% CI, 9%-12%]) who received noninvasive ventilation. The median positive end-expiratory pressure (PEEP) was 14 (IQR, 12-16) cm H2O, and Fio2 was greater than 50% in 89% of patients. The median Pao2/Fio2 was 160 (IQR, 114-220). The median PEEP level was not different between younger patients (n = 503 aged ≤63 years) and older patients (n = 514 aged ≥64 years) (14 [IQR, 12-15] vs 14 [IQR, 12-16] cm H2O, respectively; median difference, 0 [95% CI, 0-0]; P = .94). Median Fio2 was lower in younger patients: 60% (IQR, 50%-80%) vs 70% (IQR, 50%-80%) (median difference, −10% [95% CI, −14% to 6%]; P = .006), and median Pao2/Fio2 was higher in younger patients: 163.5 (IQR, 120-230) vs 156 (IQR, 110-205) (median difference, 7 [95% CI, −8 to 22]; P = .02). Patients with hypertension (n = 509) were older than those without hypertension (n = 526) (median [IQR] age, 66 years [60-72] vs 62 years [54-68]; P < .001) and had lower Pao2/Fio2 (median [IQR], 146 [105-214] vs 173 [120-222]; median difference, −27 [95% CI, −42 to −12]; P = .005). Among the 1581 patients with ICU disposition data available as of March 25, 2020, 920 patients (58% [95% CI, 56%-61%]) were still in the ICU, 256 (16% [95% CI, 14%-18%]) were discharged from the ICU, and 405 (26% [95% CI, 23%-28%]) had died in the ICU. Older patients (n = 786; age ≥64 years) had higher mortality than younger patients (n = 795; age ≤63 years) (36% vs 15%; difference, 21% [95% CI, 17%-26%]; P < .001).

Conclusions and Relevance In this case series of critically ill patients with laboratory-confirmed COVID-19 admitted to ICUs in Lombardy, Italy, the majority were older men, a large proportion required mechanical ventilation and high levels of PEEP, and ICU mortality was 26%.

https://jamanetwork.com/journals/jama/fullarticle/2764365

 

[Keela Too]

I have to say I LOVE this forum! Things are discussed openly, with members putting forward ideas knowing that, although problems will be pointed out, it will be in a reasoned manner. Then reasoned discussion follows on afterwards. This is how great minds should work together everywhere!

Xx

 

[Amw66]

The most disturbing UK figure for me is the very low number of " recovered" on the worldometer site - 135 out of over 56 000 cases.

This is very low.
It may be due to figures being based til recently on hospital admissions only?

 

[Keela Too]

The most disturbing UK figure for me is the very low number of " recovered" on the worldometer site - 135 out of over 56 000 cases.

This is very low.
It may be due to figures being based til recently on hospital admissions only?

It might also be that “recovery” (however it is defined) takes longer to be sure about than “death”. So recovery figures might lag the death figures by a couple of weeks perhaps?

 

[hinterland]

The most disturbing UK figure for me is the very low number of " recovered" on the worldometer site - 135 out of over 56 000 cases.

This is very low.
It may be due to figures being based til recently on hospital admissions only?

Yes, I've noticed the low recovery figures in some of the reporting generally, not just UK, and wondered how this is defined and measured. It seems to be a very low proportion of cases that are reported as 'recovered'.

 

[Leila]

From what I understand "recovered" means 2 negative tests within 24hrs, see here. Edit: Page 3 shows different criteria by different institutions.

Maybe there's just not enough ressources anymore to follow up on patients and they focus on the ones that needed hospital care?

(Edit correction)

 

[Jonathan Edwards]

I think the recovered figure for the UK must meaningless. Maybe it needs negative tests as well as being better and nobody is bothering to do tests a second time because there aren't enough.

What to me are of more interest are the figures from China. There are a lot of recoveries there but not perhaps as many as one would like to see. Again this may be an artefact but I suspect the real long term problem for Covid19 is going to be those who have suffered sufficiently severe organ failure to require high level supportive care for years. Some may need dialysis or transplants. The resource implications are considerable.

 

[Sly Saint]

I think the recovered figure for the UK must meaningless. Maybe it needs negative tests as well as being better and nobody is bothering to do tests a second time because there aren't enough.

What to me are of more interest are the figures from China. There are a lot of recoveries there but not perhaps as many as one would like to see. Again this may be an artefact but I suspect the real long term problem for Covid19 is going to be those who have suffered sufficiently severe organ failure to require high level supportive care for years. Some may need dialysis or transplants. The resource implications are considerable.

given that they have now admitted the antibody tests don't work
https://www.s4me.info/threads/coronavirus-worldwide-spread-and-control.13287/page-111#post-251165

how can anyone be sure of the 'recovery' figures anyway.

 

[Jonathan Edwards]

given that they have now admitted the antibody tests don't work
https://www.s4me.info/threads/coronavirus-worldwide-spread-and-control.13287/page-111#post-251165

how can anyone be sure of the 'recovery' figures anyway.

I don't think the antibody test is a test of recovery. It is a way of identifying people who have had the infection even if not ill or carrying virus now. Recovery is recovery - back to functioning normally.

 

[Adrian]

It might also be that “recovery” (however it is defined) takes longer to be sure about than “death”. So recovery figures might lag the death figures by a couple of weeks perhaps?

Some have expressed concern that the death figures aren't very timely in that they are saying it can take a few days for them to be reported from the hospital.

The recovered figure seems to have been constant for a while so my guess would be its not being collected/reported.

It does make me wonder how a decent strategy can be worked out and run without good reliable figures.

 

[Sly Saint]

Recovery is recovery - back to functioning normally.

hmm I can think of a few 'experts' who believe 'recovery is a journey, not a destination'