54 | New Scientist | 8 February 2020
Going viral
I had my flu vaccination, then
promptly came down with a really
bad case of flu three weeks later.
How can that happen?Nikki Walters,
Wakefield, West Yorkshire, UK
The first possibility is that perhaps
it wasn’t the flu. The vaccine only
protects against the influenza
virus but there is a whole menu
of possibilities when it comes to
diseases with flu-like symptoms.
Secondly, even if it was
influenza that you had, there is a
chance you caught a strain that
wasn’t covered by the vaccine.
There are many different strains
of influenza virus, and several
can be circulating at once.Jane Monroe
Arcata, California, US
Every year, immunologists must
predict which strain, or strains,
of flu virus will dominate during
flu season. This is so the correct
vaccine can be produced. Making
this prediction is difficult, so
sometimes the vaccine doesn’t
match the virus strain that
is circulating most widely.
There are multiple strains of
influenza virus circulating during
flu season, and you may have
been infected by one of those that
wasn’t included in the vaccine.Lewis O’Shaughnessy
London, UK
More than 200 different viruses
cause flu-like symptoms. Each has
different antigens – parts of the
virus that would be targeted by
antibodies – and so requires a
different vaccine. On top of this,
influenza viruses are able to
mutate rapidly, so vaccines are
only effective for a few years.Rob Colebrook
Clee Hill, Shropshire, UK
Firstly, and most importantly, a flu
vaccine can’t give you influenza.
Secondly, unless you had a blood
test or nasal swab to prove it, it
is unlikely that you actually had
influenza. When I practised as aGP, the vast majority of patients
who thought they had influenza
were more likely to have been
infected with a parainfluenza
virus – which is like influenza –
or a rhinovirus or adenovirus,
which both cause a cold.
Thirdly, it takes between two
and four weeks after having the
vaccine for antibodies to influenza
to develop, so it is possible to get
flu before you have full protection.Michael Allen
Ottawa, Ontario, Canada
A surveillance system developed
by the World Health Organization
attempts to identify the strains of
flu circulating around the world
from swabs of the nose and throat
of patients with flu symptoms.
The WHO then recommends
the strains to be included in the
vaccine for the upcoming season.
There isn’t always a good match
between the strains in the vaccine
and those that actually cause
influenza that year. In addition,
some countries, including
Australia, choose to follow
their own recommendationsrather than those of the WHO.
A 2018 review by the Cochrane
Collaboration found that flu
vaccine cuts the risk of healthy
adults getting influenza from
2.3 per cent without vaccination
to 0.9 per cent with it.John Philpott-Howard
London, UK
Vaccines are never 100 per cent
effective in all people, although
two doses of measles vaccine (as
MMR) come close, giving more
than 99 per cent protection.
Also, immunisation can result
in a suboptimal immune response,
for a variety of reasons: poor
vaccine administration technique,
for example, or because of other
health problems affecting your
immune system at the time.
It is important to note that even
if you get infected by the influenza
strain that is in the vaccine thatyear, it is likely that you will have a
modified illness. Although it may
feel like a bad case, the vaccine
may have partially protected you
from even more severe disease.Tim Lewis
Consultant chest physician,
Landshipping, Pembrokeshire, UK
It is possible to be infected with
influenza virus when attending a
crowded surgery for the injection
and fall ill before immunity has
had time to develop.Anna Butcher
Brookton, Western Australia
My GP advises vaccination
some months ahead of the flu
season so that I have maximum
immunity when it arrives.David Critchard
Exeter, Devon, UK
Like me, my son is allergic to
vaccines cultured in eggs.
I decline to be vaccinated, but
he is a surgeon, so is vaccinated
as soon as the latest one
becomes available. He is
then ill, sometimes needing
intensive therapy unit treatment
for up to a month.
Two years ago, he was
vaccinated and had the allergic
reaction. Some time afterwards,
a patient was flown in, having
been shot in a remote region of
Pakistan, where people often go
unvaccinated. He was patched
up, but my son and his colleagues
went down with a dangerous flu.
It hadn’t been included in that
year’s vaccine. My son infected
his sister. The virus killed the
baby she was carrying and
almost killed her.
Even if the effects of
vaccination can be unpleasant,
the consequences from the lack
of it can be much worse. ❚This week’s new questions
Awful eaters Foxes have the most repulsive smell, alive
or dead. We often see dead foxes on our farm and they just
decompose in situ. So, does anything eat foxes? Anna Butcher,
Brookton, Western AustraliaThe nose knows Rust doesn’t appear to release molecules
into the air? So how does it have a smell? Hugh Cartwright,
Victoria, British Columbia, CanadaWant to send us a question or answer?
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STEPHEN DALTON/NATUREPL.COMApart from microorganisms,
does anything eat foxes?