BBC Focus - 04.2020_

REVIEW REALITY CHECK

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ILLUSTRATION:

MARIANA

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VILLARREAL

WHYAREWEBEINGADVISEDTOWASHOURHANDS?

Coronavirusis a respiratoryillness,meaningit is mostly

spread throughvirus-laden dropletsfrom coughsand

sneezes.If youdon’tcatchcoughsandsneezesina tissue

anddisposeofit,theviruscanenduponsurfaces.If

someonetouchesthat contaminatedsurface,the virus

cantransferontotheirhand. If youhavetheviruson

yourhands,youcan infectyourself bytouchingyour

eyes,mouth or nose. Youmight think that you don’t

touchyourfaceveryoften,buta 2015studyfoundthat

peopletouchtheirfacesanaverageof 23timesanhour.

While washing your hands is useful in preventing

yourself from getting infected, this is not the main

reason the government recommends it. “It’s all about

stoppingthe spread,”says SallyBloomfield, honorary

professorattheLondonSchoolofHygieneandTropical

Medicine.“Whenit comestostoppingthespreadofthe

seriousinfection in this country, the public have a huge

role to play.”

DOESSOAPKILLCORONAVIRUS?

Coronavirusis an‘envelopedvirus’.Thismeansit hasa

protectiveouter layerknown asa ‘lipid bilayer’.Each

moleculemakingupthislayeris shapedlikea tadpole,

with a water-loving (hydrophilic) head and a water-

hating (hydrophobic) tail. These molecules arrange

themselvesintoa ‘bilayer’: twolayers piledon top of

eachotherintoa sheet,withtailspointinginwardsand

heads pointing outwards. The molecules are pulled

closelyintoeachothertoprotectthehydrophobictails

fromthewater inyourrespiratorydropletswhen you

cough or sneeze. The hydrophilic heads are ‘sticky’,

meaningthevirusis effectiveat adheringtoyourhands

• perfectfora microbethat’stryinghardtoinfectyou.
  Soap molecules also have this tadpole structure,
  which is what makes it so useful. Because the soap
  moleculesaresosimilartotheonesmakinguptheouter
  layerofthevirus,themoleculesinthelipidbilayerare
  as strongly attracted to soap molecules as they are
  to each other. This disrupts the neatly-ordered shell
  aroundthevirus,dissolving it in the running water and
  killing the virus.

“Whenit comestostoppingthespreadof

the seriousinfectioninthiscountry,the public

have a huge role to play”

ABOVE

Coronavirus

hasa

protective

outerlipid

bilayer.It ’s

madeupof

tadpole-

shaped

molecules

with

water-loving

heads,and

water-hating

tails

DOESANTIBACTERIALHANDSANITISERKILLVIRUSES?

Yes.Alcohol-basedhandsanitiserwillkillvirusesif soap

andwaterarenotavailable.Alcoholis anantisepticandcan

killenvelopedvirusessuchascoronavirus,butmakesureit

contains 60 to 95 percentalcohol.However,if yourhands

arevisiblydirty,you need to use soap and running water to

clean the dirt off.

WILLHAND-WASHINGSTOPMEFROMCATCHINGTHEVIRUS?

It’s impossible to know whether any particular case of

coronavirus could have been prevented by better hand-

washing.Whileit ispossibletocontractcoronavirusfrom

touchingyourfacewithvirus-contaminatedhands,youcan

also catch it directly from the coughs or sneezes of an

infected person. So, while washing your hands won’t

eliminateyourriskofinfection,it’sa sensibleandpowerful

safetymeasure.“It’sa littlebit,I think,likewearinga car

seatbelt,inthatit’sunlikelyyou’llgetinfectedat thepresent

time,inthe samewayasyou’reunlikelytohave a crash

whenyougooutinyourcar,”saysBloomfield.“Youstill go

outinyourcar,butyoualwaysbeltupyourseatbelt.”

Wedo, however, knowthat hygiene measures – hand-

washing,self-isolatingwhenill,disposingoftissues,etc.–

dopreventthespreadofrespiratorydiseases.Followingthe

2003 outbreakofSARS-CoVinHongKong,theDepartment

of Health in China wanted to know how effective the

government’s efforts at containing the disease were. Since 2

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