One big question is if the corona virus is here to live, too. When attempts to
eradicate it fail, then there is a high likelihood it will become widespread.
This could mean, as with influenza, that deaths occur every year as the virus
circulates, until a vaccine is created. When people who are infected but do
not have symptoms will spread the virus, it will
be harder to control its
spread, making it more likely that the virus will become endemic to them.
Some cases of infected people with no symptoms have occurred, but it is still
uncertain whether such asymptomatic or mild cases are normal and whether
or how contagious they are. "Probably we are looking at a virus that will be
with us for a long time, possibly forever," Mackay says.
Asymptomatic cases differentiate the new virus from related corona virus,
which causes severe acute respiratory syndrome (SARS). This virus had a
global epidemic in 2002–03 but usually only spread
until people were sick
enough to need hospital care. When outbreaks were brought under control in
hospitals, SARS had been controlled. There's no proof the virus continues to
spread in humans, says Mackay.
If control measures are successful, and transmission slows down so that no
more than one person
infects per infected person, the current outbreak may
simply peter out, Cowling says.
Is the Virus Likely To Change?
Some researchers are worried that the pathogen will mutate as China's corona
virus spreads so that it can spread more easily, or become more likely to
cause disease in young people. The virus has currently caused severe illness
and death,
particularly in older people, especially those with pre-existing
conditions such as diabetes and heart disease. The youngest victim identified
so far, is a 36-year-old Wuhan man with no documented pre-existing health
conditions.
Kristian Andersen, a Scripps Research infectious-disease
expert in La Jolla,
California, is not concerned about the virus becoming more virulent. He says
viruses are continually mutating as part of their life cycle, but these mutations
usually don't make the virus more virulent or cause more serious illness. "I
can't think of any cases of this having happened with pathogenic outbreaks,"
he says.
In cases where a virus moves from one animal host to another species—
which is possibly how the current corona virus began infecting humans—
there may be a selection pressure in the new host to enhance survival, but that
seldom, if ever, affects human disease or the transmissibility of the virus.
Some mutations damage the virus, or have no consequence. A 2018 study of
SARS in primate chambers showed that his virulence was possibly
diminished by a mutation sustained by the virus during the 2003 epidemic.
Scientists have exchanged hundreds of genetic sequences from the latest
corona virus strains, and a steady supply of those samples will show genetic
changes as the epidemic progresses, MacKay said. "If they change sequence,
viruses
do not change behavior, and we need to see persistent or consistent
virus change," he says.
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