The logic of surviving the Coronavirus pandemic

In this arti­cle, we sug­gest what we con­sid­er, in large part poten­tial­ly instead of dras­tic quar­an­tine for basi­cal­ly every­one, to be the most log­i­cal and most promis­ing approach to sur­viv­ing the Coronavirus pan­dem­ic, both on an indi­vid­ual and on a sys­temic lev­el. We draw con­clu­sions from infor­ma­tion uncov­ered and dis­cussed by the med­ical sci­en­tif­ic com­mu­ni­ty and by med­ical prac­ti­tion­ers, and give prac­ti­cal instruc­tions on what to do.

We will start with the core points and leave con­tex­tu­al elab­o­ra­tion of our views to the lat­ter part of this as well as to sub­se­quent articles.

The one question that really matters

It is wide­ly esti­mat­ed that around 70 % of the respec­tive pop­u­la­tion will even­tu­al­ly be infect­ed by the Coronavirus. While the major­i­ty of infec­tions appears to result benign, a large num­ber of those infect­ed require hos­pi­tal­iza­tion, close to 10 per­cent can cur­rent­ly be esti­mat­ed to require inten­sive care, and between 1 and 3 per­cent to die. It has by now become appar­ent that not just old­er peo­ple with seri­ous comor­bid­i­ty are at risk of seri­ous health prob­lems or even death from a Coronavirus infec­tion, and we per­son­al­ly are aware of the case of a 40 year old healthy man very quick­ly need­ing inten­sive care after catch­ing the virus (he like­ly became infect­ed in the hos­pi­tal where he had work assign­ments as a crafts­man, and con­tin­ued to work there while already hav­ing fever; he has since died in the hospital’s ICU). Measures against the spread of the virus as dras­tic as those pur­port­ed­ly employed in the People’s Republic of China, though pur­port­ed­ly suc­cess­ful, can not be expect­ed to be employed in the exact same way in the rest of the world. The one and only ques­tion that mat­ters, there­fore, for both the indi­vid­ual and the entire health care sys­tem which risks to become over­whelmed by a steady inflow of new patients, is not so much how to avoid an infec­tion but how to rad­i­cal­ly min­i­mize its diverse con­se­quences. The one ques­tion that mat­ters is how to avoid need­ing hos­pi­tal­iza­tion and par­tic­u­lar­ly inten­sive care, and ulti­mate­ly how to avoid to die of Coronavirus-induced pneumonia.

The logical answer

Diverse hints help­ful at attempt­ing to craft a con­fi­dent answer to this ques­tion have been men­tioned, often in pass­ing, in media appear­ances as well as in media and sci­en­tif­ic pub­li­ca­tions by mem­bers of the med­ical sci­en­tif­ic com­mu­ni­ty, and we will seek to put them into their sys­tem­at­ic con­text while elab­o­rat­ing more deeply on the core point.

The two cru­cial dots need­ing to be con­nect­ed were pro­vid­ed by Professors Dr. Christian Drosten, Charité Berlin, and Dr. Clemens Martin Wendtner, Ludwig-Maximilians-Universität München, as well as by the pul­mo­nolo­gist Bruce L. Davidson MD, MPH, Seattle, respectively.

Professors Drosten and Wendtner, for their part, observed that for the first 5 days after the occur­rence of symp­toms the virus repli­cates mas­sive­ly in the throat, much unlike the SARS virus of 2003 was observed to be doing, and that this mas­sive repli­ca­tion was already declin­ing when mea­sure­ments began (imply­ing that from a cer­tain point onwards, in line with Professor Drosten’s obser­va­tions, pha­ryn­geal swabs will often result in false neg­a­tive test­ing results). They also found a new­ly mutat­ed vari­ant of the virus which was first only detect­ed in the throat and a few days lat­er also mas­sive­ly repli­cat­ing in the lung. Symptom onset, in case an infect­ed per­son does not remain asymp­to­matic, has since been esti­mat­ed to occur around 5 days into the course of an infec­tion, around the time the viral pop­u­la­tion in the throat peaks. Around this time, an infec­tion often starts affect­ing the lungs. If lung involve­ment remains mild, it will start to reverse after a few days; if it results in pneu­mo­nia, the lat­ter will either heal up with­in one to two weeks or progress rapid­ly to severe disease.

Dr. Davidson, for his part, remind­ed of a sci­en­tif­ic study that had shown that even com­plete­ly healthy peo­ple do aspi­rate flu­id from the nose or throat to the lungs dur­ing sleep.

Combined, these find­ings sig­ni­fy that, in the case of a Coronavirus infec­tion, peo­ple can be expect­ed to even­tu­al­ly aspi­rate flu­ids with large viral loads from their throats into their lungs, even­tu­al­ly over­whelm­ing the body’s pro­tec­tive mech­a­nisms. Importantly, this can hap­pen, accord­ing to the data pro­vid­ed by Professors Drosten and Wendtner, even before the infect­ed expe­ri­ence sig­nif­i­cant rec­og­niz­able symptoms.

Adding to this the immuno­log­i­cal com­mon­place that a suc­cess­ful immune response to a path­o­gen­ic attack is in large part a ques­tion of quan­ti­ty – sim­ply put: how many pathogens col­lide with how many immune cells – the log­i­cal con­clu­sion to be drawn is that in order to avoid falling seri­ous­ly ill from a Coronavirus infec­tion, if not to avoid what can be called an infec­tion at all (pathogens are present in the throat at all times, but nor­mal­ly in man­age­able quan­ti­ties), the (poten­tial) viral pop­u­la­tion in the throat must be active­ly min­i­mized by all suit­able means at our dis­pos­al. This means pre­vent­ing the virus from pop­u­lat­ing the throat in sig­nif­i­cant quan­ti­ties in the first place, and rad­i­cal­ly sup­press­ing any virus pop­u­la­tion that may have devel­oped in the throat by reg­u­lar­ly employ­ing dis­in­fec­tants with known sig­nif­i­cant antivi­ral capa­bil­i­ties against the nov­el Coronavirus, and which are safe to use in the throat. This should, in most cas­es, ensure that we can safe­ly bridge the time span the immune sys­tem requires to ulti­mate­ly gain the upper hand against the virus and pro­vide us with long term immunity.

While this appears to pri­mar­i­ly help the indi­vid­ual to win his per­son­al bat­tle against the Coronavirus, it at once helps win­ning the war in gen­er­al. Since evi­dence at least indi­rect­ly sug­gests that infec­tions pre­dom­i­nant­ly occur via micro­scop­ic flu­id drops trans­mit­ted from an infect­ed per­son over the air, through speak­ing and cough­ing, a dras­ti­cal­ly sup­pressed viral load in the throats of infect­ed peo­ple, whether they show symp­toms or not, reduces the risk of virus trans­mis­sion, slow­ing and even­tu­al­ly even halt­ing its spread.

In this arti­cle, we will address the issue in these quan­ti­ta­tive and prac­ti­cal aspects. In a fol­low-up arti­cle we plan to address the ques­tion of who is espe­cial­ly vul­ner­a­ble and should there­fore observe (in part poten­tial­ly with help from oth­ers) the pre­cau­tion­ary mea­sures of con­tact avoid­ance as well as min­i­miza­tion of the viral load in the throat with extreme rig­or, and who is rather unlike­ly to devel­op severe disease.

What to do

Of course: avoid expo­sure, espe­cial­ly via inhala­tion, and wash your hands. But, as men­tioned, you can and should seri­ous­ly con­sid­er to do more:

Gargle with hydro­gen per­ox­ide at a con­cen­tra­tion of 1 % for 60 sec­onds (in case this seems long to do in one go, con­sid­er that you can do 4 times 15 sec­onds or 6 times 10 sec­onds). Do not swal­low the solu­tion, but spit it out after gargling.

How often?

One to a max­i­mum of four times a day. The most impor­tant – and nor­mal­ly only – time to do it is before going to sleep to min­i­mize the viral load that may be aspi­rat­ed into the lungs dur­ing sleep. 

When? In what circumstances?

1. Once a day before going to bed as a pre­ven­tive mea­sure, even if you do not expect to have been infect­ed yet.
2. Since you may be infect­ed even with­out expe­ri­enc­ing symp­toms, you should do it before an unavoid­able inter­ac­tion with vul­ner­a­ble per­sons, before vis­it­ing a doctor’s office or pos­si­bly to pre­vent trans­mis­sion gen­er­al­ly if you have to go out, but not more than 4 times a day and not in case your mucosa in the mouth feels irri­tat­ed or burn­ing. DO NOT DISREGARD THE SOCIAL DISTANCING MEASURES WHILE THEY ARE STILL IN FORCE. What we sug­gest here is an addi­tion­al safe­ty mea­sure in and after sit­u­a­tions where you can­not avoid con­tact with oth­ers, pri­mar­i­ly the espe­cial­ly vulnerable.
3. Of course, in order to dimin­ish the risk of get­ting infect­ed your­self, you should equal­ly do it as soon as pos­si­ble after com­ing in con­tact with many dif­fer­ent peo­ple or with peo­ple who are infect­ed or show any signs of pos­si­bly being infected.
4. If you have symp­toms or are test­ed pos­i­tive­ly, do it to min­i­mize viral load, but not more often than four times a day.

Who?

Generally every­one, but not chil­dren, even if you sup­pose they could be excep­tion­al­ly vul­ner­a­ble (which typ­i­cal­ly they are the least to be), and not if you can­not coor­di­nate gar­gling with­out swal­low­ing the mouth­wash.

Be care­ful and always use the right con­cen­tra­tion. Probably you will find the hydro­gen per­ox­ide in a 3 % or 6 % con­cen­tra­tion. Dilute it with water to arrive at 1% (case 3% com­bine one part hydro­gen per­ox­ide with two parts water, case 6% com­bine one part with 5 parts water). If the mucosa does feel sig­nif­i­cant­ly irri­tat­ed, you could fur­ther dilute it to 0.5 % (com­bine 1 part 1 % solu­tion and 1 part water). In case you choose to use anoth­er sub­stance, fol­low the respec­tive instruc­tions, nev­er sup­pose that more works bet­ter! The Chinese lady who pur­port­ed­ly ate 1.5 kg of gar­lic seri­ous­ly dam­aged her body.

In addi­tion:

1. Dr. Davidson advis­es to “wash your hands and face well with soap and warm water, includ­ing — on a fin­ger — a quar­ter-inch into each nos­tril. Then gen­tly blow your nose. DON’T use those irri­gat­ing devices, like neti pots, that might force virus fur­ther inside! Brush your teeth and tongue, swish and spit, and gar­gle once or twice with an anti­sep­tic mouth­wash. Limit seda­tion before sleep dur­ing an epi­dem­ic [alco­hol, sleep­ing pills].” (The “don’t use irri­gat­ing devices” sup­pos­es that you have just caught the virus and it is still in your nos­tril and you don’t want to do any­thing to bring the virus from there to the place where it best can repli­cate, the deep throat; apply this thought to your own situation.)
2. Regarding the mouth­wash, which Dr. Davidson does not spec­i­fy (this could mean that in his view an OTC drug store mouth­wash labelled “anti­sep­tic” is suf­fi­cient if you clean the mouth as he pro­pos­es), mea­sure a small mouth­ful of the dilut­ed solu­tion (ca. 10-20 ml), take it into your mouth and tilt your head back. Gargle and swish the mix­ture around in your mouth for 60 seconds.
3. Spit the solu­tion out after gargling.
4. If used appro­pri­ate­ly in the pro­posed con­cen­tra­tion, major side effects are rare, even when swal­lowed, but red­ness and irri­ta­tion of the gums can hap­pen yet should go away after a few hours. Do not use it again on irri­tat­ed mucosa. In the improb­a­ble case that this becomes a major prob­lem, lim­it it main­ly to the throat or switch to anoth­er substance.

To facil­i­tate a some­what deep­er con­tex­tu­al under­stand­ing of what we sug­gest, in the remain­ing part of this arti­cle we will pro­vide some addi­tion­al as well as more detailed infor­ma­tion on

• why wash­ing and dis­in­fect­ing the mouth can pre­vent pneu­mo­nia and why to do it espe­cial­ly before going to bed,
• which oth­er mouth­wash options exist and what viral reduc­tions you can expect,
• what else you could do to min­i­mize viral load in the throat.

Why washing and disinfecting the mouth can prevent pneumonia and why to do it especially before going to bed

Dr. Davidson points to a find­ing that prob­a­bly all nor­mal peo­ple will have aspi­rat­ed throat con­tent by the end of a giv­en week and that this is the way pneu­mo­nia usu­al­ly devel­ops. (There are many stud­ies demon­strat­ing suc­cess­ful pre­ven­tion of pneu­mo­nia by using mouth­wash in the ICU setting.)

Chances of aspi­ra­tion of big­ger amounts are even high­er if the sleep is deep­er, such as after tak­ing a sleep­ing pill or a cou­ple of beers or shots, or in old­er peo­ple who have swal­low­ing coor­di­na­tion prob­lems, or in the case of lung dam­age due to smoking.

All of which is why, in addi­tion to thor­ough­ly wash­ing one’s hands, face and nos­trils with warm water and soap, brush­ing one’s teeth and tongue, swish­ing and spit­ting, Dr. Davidson rec­om­mends to gar­gle once or twice with an anti­sep­tic mouthwash.

What other mouthwash options are there and what viral reductions can you expect

But what mouth­wash? Any mouth­wash with the label ‘anti­sep­tic’?

We are obvi­ous­ly look­ing for an anti­sep­tic mouth­wash that is known or at least log­i­cal­ly like­ly to be effec­tive against the nov­el Coronavirus, and that, impor­tant­ly, is not known to do any harm.

What mouthwash is effective against the Coronavirus?

Of the sub­stances that Kampf et al. report to be effec­tive against the nov­el Coronavirus, the fol­low­ing except ethanol are used dur­ing den­tal pro­ce­dures or to pre­vent pneu­mo­nia dur­ing a stay at the inten­sive care unit, they have been used for many decades also at home, are read­i­ly avail­able and seem suf­fi­cient­ly safe:

Hydrogen per­ox­ide, min. 60 % ethanol and povi­done iodine are very effective,

Chlorhexidine is report­ed to be less effec­tive, but for the respec­tive study a much small­er dose was used than the usu­al one which had already been shown to be effec­tive against coat­ed virus­es such as the Coronavirus.

Are the pro­posed anti­sep­tics able to pre­vent the Coronavirus from pop­u­lat­ing the throat in sig­nif­i­cant quantities?

Hydrogen per­ox­ide 0,5 %, min. 60 % ethanol and povi­done iodine can all reduce a Coronavirus strain after 1 minute by more than 4 orders of mag­ni­tude (Kampf et al.). 

This means that the aver­age virus RNA load per swab mea­sured by Professors Drosten and Wendtner dur­ing the first 5 days of 6.76×10^5 (max­i­mum: 7.11X10^8 copies/swab) would be reduced to 70 copies (resp. 70000 max­i­mum). Interestingly, they found that virus iso­la­tion suc­cess also depend­ed on viral load: sam­ples con­tain­ing <10^6 copies/ml nev­er yield­ed a “liv­ing” infec­tious virus.

This means that after a mouthrinse/gargle, viral trans­mis­sion as well as aspi­ra­tion of infec­tious mate­r­i­al to one’s own lungs can be expect­ed to be dras­ti­cal­ly minimized.

1. Hydrogen per­ox­ide. The effec­tive con­cen­tra­tion of 0,5 % is rel­a­tive­ly small, 1 % is com­mon for a med­ical gar­gle solu­tion to be used up to 3 times a day. Generally, it does not pose any longterm risk, but of course it can be harm­ful if not used appro­pri­ate­ly, in order to not harm good oral bac­te­ria avoid using it more than once a day for a longer duration.
2. Povidone iodine is regard­ed as a good option but can be harm­ful if one has thy­roid prob­lems or an aller­gy against it.
3. 60 % ethanol is not used in clin­i­cal settings/trials as a mouth­wash, one would prob­a­bly have to mix it by com­bin­ing alco­hol in high con­cen­tra­tion with pure (96%) ethanol. I tried it myself so see how it feels (burn­ing!), after a friend of mine, a doc­tor and depart­ment head in a German hos­pi­tal, told me that she had told her par­ents, liv­ing in an east­ern European coun­try where anti­sep­tics were soon out of sup­ply, to use their self-burnt vod­ka hav­ing a 60 % con­cen­tra­tion for hand dis­in­fec­tion and tak­ing a good swal­low of it in the mouth when unsure about poten­tial infec­tious con­tacts, espe­cial­ly when hav­ing to leave their home. Interestingly, the idea of mouth dis­in­fec­tion was per­fect­ly nat­ur­al to her just from her clin­i­cal under­stand­ing of a viral pneu­mo­nia and the Coronavirus, just as every sin­gle oth­er med­ical prac­ti­tion­er I have so far spo­ken to said that this was a good idea. Interestingly, also, my friend, hav­ing advised her par­ents on mouth dis­in­fec­tion, did not apply it to her­self, telling me: “I would not know how often to do it dur­ing the day as I am exposed to infect­ed patients all the time; I just have to some­how get through it.” It is, of course, bet­ter to do it four times a day than not at all, and it should not be nec­es­sary at all to to it after every sin­gle patient contact.
4. Another sub­stance used as a gar­gle dur­ing den­tal pro­ce­dures and to pre­vent pneu­mo­nia in a hos­pi­tal set­ting is chlorhex­i­dine in a con­cen­tra­tion of 0,12 per­cent. In this con­cen­tra­tion it seems to gen­er­al­ly have a good killing activ­i­ty against coat­ed virus­es but was only test­ed against coro­na virus­es in a con­cen­tra­tion of 0.02 per­cent and in this con­cen­tra­tion found to be less  effective.
5. There is also evi­dence that the Listerine anti­sep­tic, a com­mon mouth­wash, prob­a­bly has antivi­ral activ­i­ty against coat­ed RNA virus­es (such as the nov­el Coronavirus which was not test­ed specif­i­cal­ly). So before doing noth­ing, this may be an alter­na­tive (and pos­si­bly con­gru­ent to Dr. Davidson’s unspe­cif­ic protocol).

In sum­ma­ry, we sug­gest to use 1 % hydro­gen per­ox­ide. Interestingly, such a rinse is a recent “com­mon sense rec­om­men­da­tion” by a den­tists’ asso­ci­a­tion to request of patients before each appoint­ment in order to pre­vent Coronavirus trans­mis­sion (if you fol­low the link above, under “Coronavirus Frequently Asked Questions” click on “Questions regard­ing coro­n­avirus, the virus which caus­es COVID-19”; the rec­om­men­da­tion we cite is the sec­ond to last and has since been updat­ed to read “1,5 %” instead of “1 %”).

What we do additionally

We per­son­al­ly do take small nuggets of very dark choco­late (90 % cocoa) in our mouths, place them between our teeth and our cheeks and just let them melt there, with­out active­ly swal­low­ing the melt­ed choco­late, to let it cov­er the mucosa, help­ing to counter the con­tin­u­ous viral attacks orig­i­nat­ing from our small chil­dren. This was dis­cussed by med­ical doc­tors (who had tried it on them­selves) in a pro­fes­sion­al online dis­cus­sion board as being suc­cess­ful in com­bat­ing a run­ning nose and cough­ing. According to our expe­ri­ence, it helps best (and prob­a­bly only) at the onset of the very first symp­toms of a throat infec­tion (sore throat).

Conclusion

Based on new sci­en­tif­ic data (the virus repli­cates mas­sive­ly in the throat before and dur­ing the first 5 days after symp­toms appear; there is viral leak from the throat into the lung) as well as the long-estab­lished under­stand­ing of how pneu­mo­nia, the severe COVID 19 com­pli­ca­tion, ini­ti­ates (via aspi­ra­tion), in order to both indi­vid­u­al­ly as well as sys­tem­i­cal­ly min­i­mize the Coronavirus impact, we pro­pose ded­i­cat­ed throat dis­in­fec­tion as described in this arti­cle as a pre­ven­ta­tive as well as a treat­ment mea­sure. Prevention of pneu­mo­nia and pre­ven­tion of viral dis­ease trans­mis­sion by dis­in­fec­tion of the mouth with anti­sep­tic solu­tions are com­mon prac­tice and regard­ed by med­ical prac­ti­tion­ers as a “com­mon sense rec­om­men­da­tion” (again, if you fol­low the link, under “Coronavirus Frequently Asked Questions” click on “Questions regard­ing coro­n­avirus, the virus which caus­es COVID-19”; the rec­om­men­da­tion we cite is the sec­ond to last and has since been updat­ed to read “1,5 %” instead of “1 %”).

Update:

Van Doremalen et al. con­clude in a paper pub­lished today, March 17, 2020, in the NEJM (Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1), DOI: 10.1056/NEJMc2004973:

“We found that the sta­bil­i­ty of SARS-CoV-2 was sim­i­lar to that of SARS-CoV-1 under the exper­i­men­tal cir­cum­stances test­ed. This indi­cates that dif­fer­ences in the epi­demi­o­log­ic char­ac­ter­is­tics [high­er trans­mis­sion of SARS-CoV-2] of these virus­es prob­a­bly arise from oth­er fac­tors, includ­ing high viral loads in the upper res­pi­ra­to­ry tract and the poten­tial for per­sons infect­ed with SARS-CoV-2 to shed and trans­mit the virus while asymptomatic.”

This con­firms that it appears high­ly advis­able that every­one seek to sub­stan­tial­ly reduce the (poten­tial or actu­al) high viral load in his throat on a reg­u­lar basis in the way described above.

Update 2:

Xi He et al. report on an exten­sive study con­duct­ed in Hong Kong, post­ed to doi.org on March 18, 2020 and since updat­ed (“Temporal dynam­ics in viral shed­ding and trans­mis­si­bil­i­ty of COVID-19”), doi: https://doi.org/10.1101/2020.03.15.20036707:

“We report tem­po­ral pat­terns of viral shed­ding in 94 lab­o­ra­to­ry-con­firmed COVID-19 patients and mod­elled COVID-19 infec­tious­ness pro­file from a sep­a­rate sam­ple of 77 infec­tor-infectee trans­mis­sion pairs. We observed the high­est viral load in throat swabs at the time of symp­tom onset, and inferred that infec­tious­ness peaked on or before symp­tom onset. We esti­mat­ed that 44% of trans­mis­sion could occur before first symp­toms of the index.”

This fur­ther con­firms that the ini­tial and there­fore pri­ma­ry bat­tle­field in the case of COVID-19, unlike with SARS 2003, is the throat, with the infec­tion mov­ing fur­ther down into the lung – even­tu­al­ly caus­ing pul­monary inflam­ma­tion – only at a lat­er stage.

So again, pre­ven­tive­ly dis­in­fect­ing the throat in the way we describe above should most­ly resolve the prob­lem as it (1.) slows the devel­op­ment of a pos­si­ble infec­tion, if not sup­press­ing it out­right, to the point where the immune sys­tem is giv­en the nec­es­sary time to devel­op a sus­tained response; and (2.) dras­ti­cal­ly reduces infectiousness.

Update 3:

It has come to our atten­tion that one clin­i­cal tri­al pre­sum­ably test­ing what we have pro­posed in our arti­cle is report­ed to have been reg­is­tered with the World Health Organization. The “Type of med­i­cine” is spec­i­fied as “Hydrogen per­ox­ide”, and the hypoth­e­sized “mech­a­nism of action” is spec­i­fied as “Non-spe­cif­ic sup­posed antivi­ral action in the throat”.

Update 4:

We have now estab­lished that the tri­al referred to in Update 3 is being con­duct­ed in Guangdong, People’s Republic of China.

The tri­al design appears to pro­vide that only patients who have already devel­oped pneu­mo­nia are includ­ed in the study. Instead of focus­ing on com­bat­ing COVID-19 induced pneu­mo­nia, how­ev­er, the study’s stat­ed intent is only “to deter­mine whether the nov­el coro­n­avirus exists in the oral envi­ron­ment, and dis­cuss the trans­mis­sion route of the virus and the influ­ence of oral gar­gle on the virus, to pro­vide ref­er­ence for the ear­ly diag­no­sis of COVID-19 and the pre­ven­tion and con­trol of infec­tion dur­ing the clin­i­cal diag­no­sis and treat­ment of oral cavity.”

We insist that deci­sive empha­sis should be put on employ­ing gar­gling with a solu­tion of hydro­gen per­ox­ide as a pre­ven­tive mea­sure, or at least as ear­ly as pos­si­ble in the course of an infec­tion. Once pneu­mo­nia has devel­oped in the absence of such pre­ven­tion, a reg­u­lar gar­gle in the way we have described in detail in this arti­cle should still help pre­vent the soil­ing of addi­tion­al lung regions or rein­fec­tion, alle­vi­at­ing dis­ease and win­ning poten­tial­ly deci­sive time for the immune sys­tem to devel­op its response.

Update 5:

The con­clu­sion that the authors of the study con­duct­ed in Hong Kong (see update 2) have drawn from their find­ings regard­ing prob­a­ble presymp­to­matic trans­mis­sion of the virus have been fur­ther cor­rob­o­rat­ed by a study done in Singapore.