Moon of Alabama Brecht quote
May 28, 2020

How Cluster Cases Drive The Covid Pandemic

One of the many mysteries of the Covid-19 pandemic is how the disease actually spreads. We were told to wash hands and about the dangers of droplets in one to one contacts. But newer evidence continues to point in another direction.

There are more and more reports about cases where the infections seems to have spread by aerosol, droplets smaller than 5μm in diameter, instead of by bigger droplets or fomites like surfaces and objects. Lambert Strether has collected reports of cluster cases in restaurants, buses, ships and a callcenter where aerosol transmission was the most likely cause:

There’s mounting evidence that airborne transmission indoors is a key — perhaps the main — pathway to SARS-COV-2 transmission. In this post I want to look at why that’s so, give examples, and suggest a simple heuristic to stay safe.

But a recent report about a South African study of a hospital cluster where 119 patients and staff caught the disease claims that most infections must have come through fomites transmission:

[O]n the whole, patients infected few other patients directly. Instead staff members spread the disease from patient to patient and from department to department—perhaps sometimes without becoming infected themselves. “We think in the main it’s likely to have been from [staff] hands and shared patient care items like thermometers, blood pressure cuffs, and stethoscopes,” says Richard Lessells, an infectious disease specialist at the KwaZulu-Natal Research Innovation and Sequencing Platform and one of the study leaders. He and the other authors found no evidence that aerosol transmission contributed to the outbreak.


A look into the very detailed and otherwise excellent original study shows why the researchers found no evidence for aerosol transmission. They never looked for any. The words 'air conditioning', 'HVAC' or similar do not appear in the 37 pages. That is because right at the start of the study the researchers excluded the possibility that aerosols may play a role:

SARS‐CoV‐2 is thought, on the basis of current evidence, to be transmitted between people through respiratory droplets and contact.
Whilst aerosol transmission may be possible in specific circumstances, particularly in the healthcare setting with aerosol‐generating procedures (i.e.endotracheal intubation, open suctioning, and manual ventilation before intubation), there is currently no evidence that aerosol transmission is an important mode of transmission more generally.

That paragraph is footnoted with a link to a WHO recommendation from March. Since then much has been learned about cluster cases in which aerosols were the most likely transmitter of the disease.

Aerosols are droplets smaller than 5 micrometers. At that small size they do not fall to the ground but float in the airstream. Unlike droplets they are not a problem outside of closed rooms as the normal air movement will start to disperse them immediately.

A study in Hubei tracked down 318 cluster creating incidents in which at least 3 persons were involved. It found that only one happened in open air. A Japanese study says that the risk of infection indoors are 19 times higher than outdoors.

An early study has found that the secondary attack rate in households defined as "the probability that an infection occurs among susceptible people within a specific group (ie, household or close contacts)" is quite low at some 35%. Other studies have come to even lower values of some 25%. There were a number of reports of families where only one or two persons were infected while other members of the household did not catch the disease.

But the overall reproduction rate R0 of Covid-19 is estimated to be somewhere between 2 and 3. That means that without isolation measures each newly infected person will on average infect 2 to 3 other persons. How does that fit with the relatively low secondary infections in households?

Science has published a must read piece that explains this conundrum:

Other infectious diseases also spread in clusters. But COVID-19, like two of its cousins, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), seems especially prone to attacking groups of tightly connected people while sparing others. It's an encouraging finding, scientists say, because it suggests that restricting gatherings where superspreading is likely to occur will have a major impact on transmission and that other restrictions—on outdoor activity, for example—might be eased.
Most of the discussion around the spread of SARS-CoV-2 has concentrated on the average number of new infections caused by each patient. Without social distancing, this reproduction number (R) is about three. But in real life, some people infect many others and others don't spread the disease at all. In fact, the latter is the norm, Lloyd-Smith says: “The consistent pattern is that the most common number is zero. Most people do not transmit.”

That's why in addition to R, scientists use a value called the dispersion factor (k), which describes how much a disease clusters. The lower k is, the more transmission comes from a small number of people. In a seminal 2005 Nature paper, Lloyd-Smith and co-authors estimated that SARS—in which superspreading played a major role—had a k of 0.16. The estimated k for MERS, which emerged in 2012, is about 0.25. In the flu pandemic of 1918, in contrast, the value was about one, indicating that clusters played less of a role.

Current estimates of the dispersion factor k for SARS-CoV-2 vary between 0.1 and 0.5. That means that cluster infections from relatively few superspreading events drive the epidemic more than single transmissions from one person to another person.

This explains the success of the Japanese strategy which brought the epidemic in that country down without ordering strict lockdown measures:

As of Thursday, Japan had confirmed more than 16,000 infections and about 900 deaths from the virus, by far the lowest figures among the Group of Seven major economies.

Japan has urged people to avoid environments with what it calls the “Three Cs”, meaning close contact in closed-off, crowded spaces, where experts say most infections have occurred.

Without knowing if the measures would work Japan picked the right strategy. Only those events and places where superspreading is most likely to occur where shunned. Additionally people in Japan actually wear their masks and are generally health conscious and disciplined.

Unfortunately it is unlikely that 'western' nations will develop such discipline.

Yves Smith has written about her recent personal experience in a hospital in Alabama where even the staff were not wearing masks and were also otherwise quite careless. This at a time where numbers in Alabama are surging.

A number of 'western' publications have claimed that democracies are more effective in fighting an epidemic.

The U.S. has now more than 100,000 deaths from Covid-19 and Britain has the highest rate of death in the world:

The UK has registered 59,537 more deaths than usual since the week ending March 20, indicating that the virus has directly or indirectly killed 891 people per million.

At this stage of the pandemic, that is a higher rate of death than in any country for which high-quality data exist. The absolute number of excess deaths in the UK is also the highest in Europe, and second only to the US in global terms, according to data collected by the Financial Times.

China, Vietnam and other countries that the U.S. likes to call dictatorships have handled the crisis much better than the so called leading democracies. In total all Asian nations seem to have had a better grip on the epidemic than many other countries. The most likely reason for this is that those cultures care far more for the collective good than for the benefit of individuals. 

The "western" cultures allow for more selfishness of the individual. But over the longer timeframe cultures that emphasizes personal liberty and ignore the common good are likely to see their empire fail.

Probably the biggest lesson we will learn from this pandemic is that we must work to change that selfish mentality.

Posted by b on May 28, 2020 at 18:16 UTC | Permalink

« previous page

Paul Craig Roberts and HCQ

A truism
"Private medicine is profit driven, which makes it susceptible to fraud. In long ago days fraud was restrained by the moral character of doctors and the respect for truth of researchers. These restraints, never perfect, have eroded as greed turned everything, integrity itself, into a commodity that is bought and sold."

Posted by: Blue Dotterel | May 30 2020 15:04 utc | 101

Blue Dotterel | May 30 2020 15:04 utc | 100

Now we are in a kind of trouble. On Roberts' side I find a link to this:

The other fast-tracked vaccine developed by the Oxford Vaccine Group proved ineffective. The vaccine produced insufficient antibodies to prevent Covid-19 infection. LINK
Ok, you open this link and see
robertfkennedyjr May 21, 2020
Link to Robert Kennedy Jr. Instagram
One day after revelations that the Gates/Fauci Moderna vax caused severe illnesses in 20% of high-dose recipients,
Bill Gates got devastating news about his other “warp-speed” COVAX bet. The Oxford Vaccine Group (OVG) spiked-protein vaccine was on an even faster track than Moderna's. In May, Melinda Gates predicted it would be jab-ready by year's end. Oxford and UK officials promised 30 million doses by September. On April 24, OVG scientists announced that macaque studies proved the vaccine effective. OVG quickly recruited 510 healthy volunteers for human trials.
Raw data released this week reveal the OVG team was lying. All vaccinated macaques sickened after exposure to COVID-19. Edinburgh University’s Eleanor Riley told Forbes the vax provided ‘insufficient’ antibodies to prevent infection and viral shedding. Vaxxed monkeys spread the disease as readily as unvaccinated.“

Any sane brain understand that such a „source“ counts nothing if one cannot find an independant access to these Raw data released this week- thing as one cannot dare to cite it in any public discussion.

Posted by: Hausmeister | May 30 2020 16:52 utc | 102

@ Hausmeister , somebody and others.. thanks for your posts here... it is illuminating..

Posted by: james | May 30 2020 16:59 utc | 103

Posted by: Hausmeister | May 30 2020 10:20 utc | 96

"Today the situation is that anybody who questions the "dangerous pandemic narrative" in the public and tries a reason-based discussion gets mobbed immediately. "

Mainstream media, governement PR and the interior ministery coordinated an attack against dissenters, defaming them as egotistical (endangering others), crazy, stupid, uneducated, sectarian, unscientific, conspiracy theorists.

It is a perfect storm.

The interior ministery, who had to enforce the "measures", knowing that neither police nor military would be able to restrict people who did not want to be restricted, engaged in a panic and fear campaign.

Main stream media went into competition with alternative and social media on "facts" trying to win by claiming alternative media to be untrustworthy. As main stream media earns money by being an effective campaign platform, this is an existential fight for them.

On top of that, the measures are - to a large part - unlawful if they cannot be backed up by necessity, so lawyers will be enjoying themselves for quite a while getting fat in the process.

Plus, "alternative", minimally invasive and evidence based medicine has joined the fight.

And there has been a fusion of West-Germany's and East-Germany's peace and civil rights movements. And some more. Think pirate party plus green party plus small businesses that used to be Christian Democrat plus FDP.

The decision process is driven by an old demography - pensioners. Something has got to give.

Posted by: somebody | May 30 2020 18:02 utc | 104

@All: anybody where who knows the real source of those "revelations"?

robertfkennedyjr on Instagram:
One day after revelations that the Gates/Fauci Moderna vax caused severe illnesses in 20% of high-dose recipients,...“

Posted by: Hausmeister | May 30 2020 21:15 utc | 105

Posted by: jinn | May 29 2020 22:55 utc | 90

I would take that as better than nothing, especially since there are many other studies that show that the virus can spread via aerosols.

Posted by: John Dowser | May 30 2020 7:56 utc | 94

There wasn't much UV during the winter and march. But yes, it is obviously more likely to happen indoors. The distance is achievable in shops, some markets, metro stations, sometimes in metro wagons, or as a warning to avoid places where it can not be achieved or for increased protection for such areas (such as use a mask when in crowded area).

>>You will encounter is sooner or later if you have a life or business.

You seem to believe that everyone lives in your trashy western countries, which allowed massive epidemics to happen. Well, there are many countries that have very low infection numbers (per capita), and like to wear masks too during such events. Masks lower viral load too, they could be combined with measures to help ones immune system, so whenever one may encounter it, they will be in better position.

Most of Asia and some other places will never encounter it, though. This isn't the US or the UK.

Posted by: Passer by | May 31 2020 7:27 utc | 106

Please check your Images more careful. The 'buring builing' image is a (likely computer based) Illustration. Hints:

- details are missing vom objects like tree, cars
- with a light so intense as the fire, there would be pitch black shadows all over the place
- ..

Posted by: plox | May 31 2020 7:31 utc | 107

Posted by: Zanon | May 30 2020 13:17 utc | 100

"France, England, Belgium, Sweden, Netherlands - all these nations have had quite high excess of deceased people this year, also debunking the claim that this is no worse than a regular flu."

Excess death is not necessarily flue death. Lots of isolated people in care homes, some countries put Covid-19 patients into care homes, so they could spread the decease :-((, full hospitals not servicing stroke patients - there are lots of possibilities when a health system gets overwhelmed by panic. Like people not going to the hospitals out of fear. What was the suicide rate? We will know these things next year if people care to look. The virus had a very selective way of working, for sure, as a lot of countries had lower mortality than usual. Hospitals using the wrong type of treatment?

The peak of deaths occurred one to two weeks AFTER the lockdown. And is back to normal mortality now. So what happened in some countries but not in others? Remember, this was the first time countries went into lockdown preemptively.

Posted by: somebody | May 31 2020 17:17 utc | 108

add to 108

For some reason, the countries with the peak in excess mortality in April tested Cloroquine from the end of March onwards. Same case for Italy.

The mysterious ways of the virus caused havoc in Spain but spared Portugal. Spain tested cloroquine. Portugal told doctors of the possibility to use it but did no testing.

Cloroquine cannot be used for - mostly black and brown people - with a well known enzyme deficiency. If this was not considered in the tests, these people got killed by the drug. Wolfgang Wodarg thinks this is the case. If this happened, doctors should be sued.

Posted by: somebody | May 31 2020 17:41 utc | 109

add to 108

Black people four times more likely to die from Covid-19 ONS finds

Posted by: somebody | May 31 2020 17:51 utc | 110

somebody | May 31 2020 17:41 utc | 109

"If this happened, doctors should be sued."

Yes, indeed, as this a long known caveat and mentioned in the accompanying paper. The experiences in Turkey with HCQ are apparently quite positive. It is a kind of standard treatment there now. And I guess any qualified doctor is able to read that paper and act accordingly. What Wodarg wrote is quite trivial and a riddle for me how a guy with such experience comes up with such stuff.

Posted by: Hausmeister | May 31 2020 19:06 utc | 111

On some US farm all employees (nearly 200 people - Mexicans sleeping together in big rooms) tested positive. Is this the end of the story that some people are immune by themselves?

Some trouble with the Lancet study that trashed HCQ. The article doesn't mention the conflicts of interest but focuses on issues like the study mentioning more casualties in Australia as had been reported by the government.

Posted by: Wim | May 31 2020 19:36 utc | 112

Still banging on about medical aspects?

The lockdown is a political decison, not a medical one.

In the UK, Dominic Cummings was 'invited' to observe the crucial SAGE meeting. Leaks from others attending show the medics' caution was over-ridden by Cummings. Ferguson reportedly convinced Johnson to go with the lockdown.

Ditto in Denmark, the politicos overrode medical advice.

Even in Germany, leaks from medicos have shown the influence of political pressure, revealed disease severity data comparable to that given by Witty, and more importantly part of the fallout - 52,000 cancelled cancer operations for example. And it is only the tip of the iceberg. Numerous other conditions will have similar numbers - diabetes, heart issues, lung issues ... Maybe that is fine if you don't have cancer, etc. Maybe they are just useless eaters so who cares if they fall away (to mirror lockdownists statements against others)?

The CIA/BND stooges are all over this, just as they were with the leaks from OPCW ... disgruntled employee, not in the loop, etc, etc.

However, this leak comes from multiple medics, not just a 'rogue employee'. Here is the original document (German only). Maybe someone could translate it to English.

KM4 Analyse des Krisenmanagements (Kurzfassung)

What is the common factor? Why is there an urgent drive to develop a vaccine for a disease that will fade anyway, and will be useless next year as a result of RNA mutation (just like the other cv variants)? Or to test a risky new technique on unwitting guinea pigs? Why give apriori legal immunity to those developing the drug? In the US, the drugs would be given by military personnel - WTF? Who benefits from under-testing these drugs? Maybe the endgame is a patent monoploy for the 'lucky' corporation combined with manditory vaccination?

For those commenting about the tests, data from China regarding PCR tests reveals an effectiveness of 60%-70%, ie little better than a guess. It also does not distinguish between viable and non-viable viral RNA. Scaring the life out of people and then giving them a test which is little better than guesswork says a lot about the ethics of those involved.

The UK stopped reporting 'recovered' statistics around the time Johnson came down with CV-19 (344 cases). Later they stopped reporting 'active' cases, so recovery can not be inferred indirectly from the data. Why? To hide the fact that most people recover? Extrapolating the upper and lower bounds of the reported data (yeah, I know, but it is all we have got) for deaths (with/from) predicts both converge to zero within a week or so. For the 'new cases' data, that equivalent extrapolation gives a zero-crossing in early September. Considerable numbers are now infected, similar to those around the peak death rate, but increasingly fewer are dying. That is a typical response for a newly emerged disease. Initial cases are very severe, and very variable symptomatically. As time goes by, the disease moderates to a level where it metaphorically becomes symbiotic ... #VirusLivesMatterToo in the modern vernacular.

Posted by: Ken Garoo | May 31 2020 21:24 utc | 113

Prof K @66

Too true.

People now walk around with looks of fear in their face, especially when approaching someone else. The young are being conditioned to fear the elderly. The 6ft / 2m 'social distance' is more Orwellian BS. Medically, a 'safe' distance would probably be 24 to 30 feet. The '6 ft' is politcal statement indicating either i) the politicos are fully aware that the disease severity is BS (probably true cf Cummings' trip to Barnard Castle, hq of GSK UK R&D), or ii) cynically want the uninformed to adopt 'unsafe' practises (eg coughing without covering their mouth) whilst thinking they are 'safe'.

One other thing, the unique political manipulation of CV statistics especially in the UK, typically merging 'with' and 'from' as one, means this years' medical statistics are totally useless for disease comparison with previous years. That is unless the data can be disentangled to an equivalent level of cause of death.

Posted by: Ken Garoo | May 31 2020 21:56 utc | 114

This guy walks into a bar...

Joe tested positive for CV, right? Or maybe not, it was just the exosomes. After many bourbons, barkeep boots Joe for passing a bad bill, bouncers manhandle him until he stumbles out the door and gets beaten senseless by drunk-hating clowns who like putting their feet on targeted neck.

Dies in the street from heart failure. Selfishness kills. Shoulda stayed at home, shoulda worn a mask.

Posted by: Curmudgeon | Jun 2 2020 16:52 utc | 115

@ b

Sorry to say but concerning Hydroxychloroquin you fell victim to a fabricated hoax:
- just one link. I have no time to compile data that clearly show that this was a politicized agenda-driven narrative from the very beginning, 19.3. and following.
No, I do not recommend that material except in urgent cases under the control of a qualified doctor at the beginning of an infection. But my nose told me something stinks fishy in this campaign.

Posted by: Hausmeister | Jun 3 2020 9:33 utc | 116

This Lancet-Gate scandal may help us to uncover the postdemocratic-neoliberal tools used to massage international politics. This is just the beginning:
Delepine, France
Fauce seems to be involved in this hoax since very long. So 3 main culprits are exposed now: Fauci, Neil Ferguson, Dominic Cummings. This be only the beginning.

Posted by: Hausmeister | Jun 3 2020 11:04 utc | 117

Coronavirus Superspreading Events - A Timeline

I've been tracking these things for a while...

Posted by: Koranteng | Jun 9 2020 18:13 utc | 118

« previous page

The comments to this entry are closed.