REALITY CHECK REVIEW
HERDIMMUNITY:CANIT
SAVEUSFROMCORONAVIRUS?
Howdoesherdimmunitywork,andis it a usefulway
tokeepinfectionratesdown?bySARARIGBY
Sarais theonlineassistantatBBCScienceFocus.
ANALYSIS
In mid-March, as coronavirus spread across the UK, Sir
Patrick Vallance – the UK government’s chief scientific
advisor – said that, to control the impact of the virus, the
country would need to build up “some degree of herd
immunity” and that about 60 per cent of the population
would need to become infected for this to happen. His
comments soon came under fire. Over 500 scientists from
UK universities wrote to the government, saying that going
for herd immunity would risk more lives than necessary.
COVID-19 has an estimated fatality rate of around 1 per
cent. If 60 per cent of the UK population became infected –
some 40 million people – that could equate to hundreds of
thousands of deaths. The Department of Health and Social
Care has since clarified that herd immunity is not part of the2 SARS-CoV (also a type of coronavirus) was a new
strain, there was no benchmark for how far it was
likely to spread. What they could measure was the
incidence of seasonal respiratory illnesses such as
the flu. Compared to the average numbers over the
previous five years, the incidence of these seasonal
illnesses dropped. The difference was particularly
clear in the months of April to June, when the public
were the most stringent with their hygiene practices.
HOW SHOULD I WASH MY HANDS?
- Start by wetting your hands with water. It doesn’t
matter whether it’s hot or cold: a 2017 study from
Rutgers University in the US found that cold water
was just as effective as hot at removing E. coli. - Next, apply either bar soap or liquid handwash.
Although some studies have shown that bacteria can
live on the surface of a bar of soap, others have found
that sharing a bar does not transmit disease. - Thoroughly rub the soap all over your hands,
making sure not to miss your thumbs, or between
your fingers and your fingertips. This part of the
process should take 20 seconds. The NHS
recommends singing Happy Birthday through twice
to count out 20 seconds, but you could choose any
song with a 20-second chorus, such as Dolly Parton’s
Jolene, or Staying Alive by the Bee Gees. - Rinse your hands well to remove the soap. Dry
them thoroughly, preferably with paper towels.
What you do after you’ve washed your hands is
important, too, says Bloomfield. “If you are, say, on an
aeroplane or a train, you can wash your hands in the
toilet, but you’ve then got to walk back to your seat,”
she says. “On an aeroplane, you’re going to be
grabbing all the seatbacks that have been grabbed by
other people. So, wash your hands, then use a hand
sanitiser when you get back to your ‘safe place’, so for
example, when you get back to your train seat or
plane seat and you’re then not going to move around.”
CAN I WASH MY HANDS TOO MUCH?
All of this extra washing could dry out the skin, so
make sure you moisturise your hands too. “If the skin
is breaking down or raw, then the soap and alcohol
disinfectants do not work as well,” Dr Craig Shapiro,
a specialist in paediatric infectious diseases in
Delaware, US, told the Washington Post. “Also, when
the skin is chapped and broken, it’s uncomfortable,
and people can be less likely to wash their hands to
prevent transmission of germs and infection.”