Moon of Alabama Brecht quote
April 03, 2020

The Science Says #MaskUp - A Look At Two New Virus Studies

There are a few new studies about the novel coronavirus epidemic that are of interest for everyone.

From Science comes a study with new epidemic data that evaluates a smartphone based system that could alarm those who have come near a person which later developed Covid-19 symptoms. Such a system is used in South Korea.

Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing

The new epidemic data in the study is of interest.

It says that the basic reproduction number R0 or R naught for the novel coronavirus is 2.0. Under normal circumstance a new carrier of the virus is likely to infect two other people. This is a higher value than for the seasonal flu but a bit lower than previously thought.

But what makes the novel coronavirus really different is that it starts to spread before the spreading person has developed symptoms.

The virus starts to replicate in significant numbers (billions per mililiter) on day 2 after the infection. The virus first replicates in the upper throat and the infected person starts to spread it to others simply by breathing, talking or coughing. Only on day 5 the infected person starts to develop first symptoms. The virus migrates into the lower lung and replicates there. The virus load in the upper throat will then start to decline. The immune system intervenes and defeats the virus but also causes additional lung damage which can kill people who have already other preexisting conditions. (Interestingly smokers seem not to develop a cytokine storms during a Covid infection and are thereby less prone to end up in the ICU.) On day 10 only few viruses will be found in the upper throat and the person will generally no longer be infectious.

The typical hospitalization point in China was only on day 9 to 12 after the onset of symptoms. At that point a test by swabs is nearly useless as the infected person will normally no longer have significant numbers of the virus in the upper throat. Reports of "defective tests from China" were likely caused by a lack of knowledge about this phenomenon. The diagnosis in these later cases should be done by a CT scan which will show the lung damage.

We do know since late January that people can transmit the virus even when they have not yet developed symptoms. An open question was how many of new infections happen during this phase.

The new Science study investigated how many infections were created by each of four infection phases or types:

  • pre-symptomatic - new infections come from an infected person who has not yet developed symptoms but will do so later
  • symptomatic - new infections come from an infected person who has already developed symptoms
  • environmental - new infections comes from some environmental contact with the virus
  • asymptomatic - new infections come from a person that will never develop any symptoms.

The study says that R0 for pre-symptomatic infections is 0.9 or 46% of all new infections. Infections from a symptomatic persons happen with an R0 of 0.8 which is equal to 40% of all new infections. Environmental infections have an R0 of 0.2 or 10% of all new infections. Infections from asymptomatic cases have an R0 of 0.1 or 4% of all new infections.

More new infections are created during the three pre-symptomatic days the virus carrier runs around then during the symptomatic one.

Washing ones hands helps but environmental infections happen only in 10% of all new infections. The pre-symptomatic carriers are, without knowing it, the biggest spreader of the disease. Millions of the many billions of viruses that get created in their throat can attach to tiny water droplets or aerosols while a person breathes, speaks or coughs.

Such spreading can be prevented when everyone wears a mask. A different new study shows that masks are very effective. Published in Nature the study is titled:

Respiratory virus shedding in exhaled breath and efficacy of face masks.

The graphic (here cut off for only corona viruses) shows how masks can keep away your droplets from the people you meet and talk to.


If the carrier of a virus wears a mask the spreading of viruses due to speaking, coughing or even breathing goes basically down to zero.

But a mask does not only protect the carrier of the viruses. While homemade or even professional surgical mask do not protect the wearer from all particles they do protect one much better from them than when one wears no mask at all.

A person rarely gets infected by just one virus particle. They come in millions attached to tiny droplets. We do not know yet how the dose of the novel coronavirus that infects a person affects the intensity of the disease. But we do know from other viruses that the dose matters. People who catch a higher dose of viruses will usually have a more intense disease. A mask can lower the virus load the wearer may receive.

One can improvise a mask from simple household objects. One can sew a mask like a surgeon does in this video. This is my preferred model which is officially recommended by German fire departments. (The pdf is in German but the pictures tell the story). This is the mask I made by following those instructions.


It is made of a folded sheet cut from a triangular arm-sling out of an old first-aid kit. A HEPA microfilter (as used in vacuum cleaners) is in between the folded sheet. A piece cut from a clean bag for vacuum cleaners will do as well. Do not use a sheet or insert that is too tight to breathe through. If one does that the air will come in from the sides of the mask and the total protection effect will be less. It can be arduous to breathe through such a mask. If you have breathing problems leave the insert out. The sheets alone are already good protection. There is a piece of wire from a big paper clip fixed inside the middle of the upper seam to fit the mask tightly around the upper nose. The lower part goes under the chin. I shaved my beard to make it a tighter fit. As I had no sewing equipment I used a stapler to fix the seams and the ribbons.

The HEPA filter catches particles down to 0.3 micrometer. Viruses are some 125 nanometer in diameter so they are smaller and could slip through. But the viruses are attached to some droplet that are bigger. HEPA filter are essentially labyrinths of small fiber and the viruses would have to bounce multiple times to get through. Finally the dose also matters.

To clean the mask of potential viruses I put it into the oven for 30 minutes at 70C (158F).

The science says that masks work. Everyone should use one. #MaskUp!

Here some additional links which might be of interest.

So far, to the frustration of both the White House and the intelligence community, the agencies have been unable to glean more accurate numbers through their collection efforts.

That's because the Chinese numbers are as correct as they can get.

Previous Moon of Alabama posts on the issue:

Posted by b on April 3, 2020 at 18:24 UTC | Permalink

« previous page

@154 Peter AU1 | Apr 4 2020 13:28 (and others)

For the record (here) it is used in humans.

"Ivermectin has been used around the world for years as a treatment for a range of conditions including head lice and scabies, and it is available as a pill, lotion and shampoo."

However, now the government is concerned people "might hoard the drug, leaving none for people who needed it for proven uses — something which had happened with other medications" and "rushing out to their pharmacies or their supermarkets buying lice treatments now because scientists are doing this work."

Posted by: imo | Apr 4 2020 18:44 utc | 201

mpn, China and SK have been using anti virals at an early stage, unlike France, where the orders are to wait respiratory problems;
before that stage the only sick people got (unless they are MPs) is paracetamol or directly oxygen.
Today, on a French gov radio, some 'authorized scientist' was mixing testing policy with 'testing for antibodies' and dismissing the testing policy of other states as based on tests we do not know the accuracy of. states

Posted by: Mina | Apr 4 2020 18:52 utc | 202


medical staff has not been tested systematically or even, proportionally, neither ppl in care homes
and we had the 1st case in Europe, back in January... so yes indeed, we love super-spreaders and we still don't quarantine positive people, we just let them in their families (the same ppl who the next day go to the baker, the supermarket, etc)

Posted by: Mina | Apr 4 2020 18:55 utc | 203

RE: testing info on worldometer.

I have emailed the site asking how they arrive at the testing numbers and have not gotten a response or found an explanation on the site.

At the moment I am not sure if the info has any practical value. Testing vs infections is about 20%. Who is getting tested? Last info I was able to find concerning this was they were only testing people who were admitted to the hospital, or who were directly exposed to someone who had been. I would assume all emergency personnel are getting tested regularly, and I would also assume all politicians are getting tested regularly.

For the most part we are basically testing those who we think have it, or those who very likely have it. If this is the case then the 20% number doesn't really have any practical value. If we were testing the general public and finding that 20% of them have positive results, that would be useful. And ridiculously terrifying.

That being said I don't see any practical value to having this information. Anybody else more knowledgeable or have a better understanding of the process or value of this info?

RE: Matt in WI.

I too live in WI, Madison to be exact. I am curious where you live in the state that you have not had any infections. There are only 13 counties out of 72 that don't have at least one case. All but one of them are some of the remotest parts of the state, mostly recreational places areas where people have hunting/fishing/recreation cabins etc. You said you expect it will spread when everyone goes back to work. This makes me assume that lots of people in your community commute to a nearby larger community for work. The counties that don't have any cases aren't really near any cities of significant size. Where do you live?

Posted by: David F | Apr 4 2020 18:57 utc | 204

@ 195 likklemore... i appreciate trudeaus response... some maturity in the face of stupidity is probably the best response.. i do think this is a perfect example of what an ignoramus trump is though... he is going to tell 3M what to do!!! meanwhile 3M is reliant on outside sources like this.. what is trumps next stupid move? but he has a cheerleading section over at pat langs, lol..

Posted by: james | Apr 4 2020 18:57 utc | 205

Laguerre, by the time the Macron handlers will change (the only plan is: GAFA integration 2.0 (incl non-anonymous posting?), ID2020, some big agreement UK/EU for an inner Marshall bailout etc. see Pepe Escobar) France will still be stuck between demonstrations and byzantine quarrels around the possibility to authorize face veils aside face masks.

Posted by: Mina | Apr 4 2020 18:58 utc | 206

I can now order facemasks in two colours closed with a tape decorated with the French colours, made by the same people who make my pullovers. €6 each with half going to a charity. True!
More seriously, Here is a list of FREE medicines given out by the Syrian Government to Coronavirus patients. Info only as I do not know some of the equivalent names in French Pharmacies.

(Quote from a tweet, without confirmation but possibly true)

Critical Corona cases:
- Meropenem 1G injection 3 a day
- Vencomycin 1G twice a day
- Azithromycin 500 once a day
- Oseltamivir 150mg twice a day, 5 days
- Hydroxychloroquinine 400 twice for one day, then
200mg twice a day for 4 days, in case of no
contraindication (G6PD, Long QT)

(In bold type Trumps remedy. My emphasis)

Posted by: Stonebird | Apr 4 2020 19:48 utc | 207

regarding test numbers, obviously a higher number is good. but be aware of the difference between number of tests performed vs persons tested.

a person might be tested multiple times due to false negatives or the need for confirmation, then tested again (may be multiple times again) as they recover before discharge.

so if the number reported are total tests performed the actual number of individuals tested may be a fraction of the total.

that's little uniformity on these data and how they're reported so it is extremely difficult to scrub. they are best used as an indication only on how aggressive testing is in a particular location.

epidemiologists will be chewing through this data for years to come but right now we're reading tea leaves at best.

Posted by: A.L. | Apr 4 2020 19:56 utc | 208

Re Ivermectin for Human use> Promising Direction; @ 144, 148, 152, 155

Used for TB treatment in Africa. Just google "TB treatment africa Ivermectin".
One example:

Posted by: Fundas | Apr 4 2020 19:59 utc | 209

From the CNN live "Brooklyn medical center to use rain ponchos and garbage bags due to gown shortage."
Obviously, Brooklyn is not in California.

Posted by: Mina | Apr 4 2020 20:21 utc | 210

Turkey steals large medical export to Spanish company. The equipment including respirators was assembled in Turkey with parts imported from China. See Independent linked by Mark sleboda at twitter.

Turkey destroys its assembly industry in one blow. The venal fools in Spain could have surely assembled this for near the same cost. Mad world.

Posted by: uncle tungsten | Apr 4 2020 20:26 utc | 211

Off-Guardian calls it right and exposes Bill Gates rip off science.

This journal is right on the tail of the beast here. Note that Gates connives to defeat natural immunity and blood plasma treatment so he can sell sell sell.

Posted by: uncle tungsten | Apr 4 2020 21:50 utc | 212

Re Ivermectin:

Recommended dosage in humans:

1.5mg per kg of body weight in a single dose.

2.0mg per kg of body weight for all other treatments.

which means if you weigh 90kg, the dose is 18mg. (0.2x90=18)

Some people have parasites inside the eyes and in those cases, vision may be affected by
the dead parasites killed by Ivermectin

usually comes in 3mg pills.

Posted by: CarlD | Apr 4 2020 21:54 utc | 213

imo 202

Has been used against parasites in third world countries for a number of years. Administered as a back liner on livestock for a long time. I tried some about ten years ago when I became ill and doctors where finding nothing. Just poured the stuff on my arm and let it soak in. Didn't make fix me though.

Posted by: Peter AU1 | Apr 4 2020 21:56 utc | 214

JohninMK @178

Thank you. It is easy to get discouraged. We have those bands sitting in a drawer. Will check for more next shopping trip.

Posted by: oldhippie | Apr 4 2020 22:00 utc | 215

CCD DSU for April 4, 2020

Spain has officially passed Italy for nCOV mortality/10M pop: 2546 vs 2526

France is now the 3rd highest nation: 1161, a hair ahead of the Netherlands at 1125 and Belgium at 971

US: 253 vs. Germany @ 160, but US without New York is 153

New York by itself would be a clear 3rd worldwide: 1834 - note they're rapidly catching up to Italy and Spain.

Posted by: c1ue | Apr 4 2020 22:05 utc | 216

@mpn #198
I would be careful with any South Korea references.
I just read somewhere - can't remember where - that the average age for nCOV infected in South Korea was under 50. This is significantly lower than other nations' average nCOV infected ages, that I've seen.
May be a function of both extensive testing to catch asymptomatic and also the nature of the nCOV spread: many of the early transmitted cases were in call centers - staffed mostly by young people.

Posted by: c1ue | Apr 4 2020 22:09 utc | 217

US, France and UK now leading the deaths per day.
China down to 1558 active cases and single digit deaths per day.
Three countries still with visions of empire and superiority. Reminds me of the old saying "Pride comes before a fall".

Posted by: Peter AU1 | Apr 4 2020 22:31 utc | 218

This is pathetic:

70% of infection routes "unknown" New corona, rapid increase in 20-40 old age

Not only did Tokyo have its first triple digit day, but 70% of the newly infected are from an unknown route, i.e. the government doesn't have any idea where they were infected.

The COVID-19 has a potential to lay waste on the Tokyo-Osaka megalopolis. If that happens, hosting the Olympics in time for the summer of 2021 will be Japan's smallest problem.

Posted by: vk | Apr 4 2020 22:37 utc | 219


The main or original outbreak in SK was this cult church.

Posted by: Peter AU1 | Apr 4 2020 22:38 utc | 220

Posted by: james | Apr 4 2020 18:57 utc | 206 he has a cheerleading section over at pat langs, lol..

Yes, I was just over there as part of my morning routine.

Lang has explicitly called for letting old people die in order to restart the economy. Go and read his latest post for yourself. He's absolutely explicit about it.

Lang has always been an utter asshole. He's right about the Middle East and despises Trump on foreign policy, which I give him credit for, but he thinks Trump is doing wonders for the economy - despite all signs to the contrary. But he makes a big deal about people being "respectful" on his blog - while insulting and demeaning people at every opportunity just to prove he's some kind of "curmudgeon" - which is a term meaning "old asshole." The amount of kowtowing his posters do to him is demeaning at best. I used to post there but got banned (as usual - I get banned almost everywhere for the usual reason that people