NZ is pinning its hopes on a vaccine

NZ is pinning its hopes on a vaccine

Coronavirus:
Modelling shows NZ’s lockdown could buy time for a vaccine


RNZ,

27
March, 2020

Modelling
done by New Zealand researchers shows the lockdown measures now in
place could buy the country more than a year for a vaccine or
treatment to be developed.


However,
the research shows that without a vaccine or cure, cases of Covid-19
will still peak well beyond hospital capacity as soon as any lockdown
ends.


The
modelling, released today by Te Punaha Matatini, shows measures
similar to those now in place can suppress the virus for up to 400
days but infections could spike as soon as they are gone, because the
population will not have developed any herd immunity.


However,
any fewer restrictions would result in a peak of at least six times
hospital capacity within just a few months.


The
paper compares a “suppression strategy” – a sustained
period of restrictions – with a “mitigation strategy”,
where controls are lifted for brief periods before being put in place
again as infections rise and ICU beds fill up.


In
all scenarios, the lockdown period is modelled to last significantly
longer than the initial four weeks that began today.


However,
one of the researchers, University of Auckland Professor Shaun Hendy,
told RNZ the current lockdown could be sufficient if all measures
were rigidly enforced.


“Provided
the contact tracing, testing, and containment strategy works then we
may be able to relax in four weeks. But we need to cut cases to just
a handful.”


The
researchers wrote that both strategies were “fraught with
uncertainty” but suppression at least had the advantage of
buying New Zealand time until a vaccine or treatment became
available.


Auckland's Queen Street on the morning of 26 March, on the first day of the nationwide Covid-19 lockdown.





Mitigation,
which aimed to let the epidemic go ahead at a controlled rate while
creating herd immunity, was “a tempting approach”, the
researchers wrote.


However
to be successful, each case would have to result in less than one
other new case.


“It
remains unknown whether this will be achievable in practice in New
Zealand. There is no evidence that it has yet been achieved in
comparable, western democracies, including those that have instigated
major lockdowns such as Italy.”


Modelling
showed that, left unchecked, the virus would infect 89 percent of the
population and up to 80,000 people would die.


Hospital
capacity would be exceeded once 40,000 people had the virus, and the
peak of the epidemic here would exceed that capacity ten times over.


Under
the strictest suppression measures, which included social distancing,
case isolation, household quarantine, and closing schools and
universities, the fatalities would drop to just 0.0004 percent –
about 20 people. Hospital capacity would not be exceeded for over a
year.


However,
that scenario would require the restrictions to remain in place until
a vaccine or other treatment was developed.


“When
controls are lifted after 400 days, an outbreak occurs with a similar
peak size as for an uncontrolled epidemic,” the researchers
wrote. “In other words, these strategies can delay but not
prevent the epidemic.”


Despite
that risk, the researchers advocated for suppression over mitigation.


“A
major advantage of suppression strategies as opposed to mitigation is
that early suppression buys time. This has two key benefits: it may
be possible to delay the epidemic for long enough that a vaccine
and/or effective treatment become(s) widely available in NZ; and it
allows NZ to learn from rapidly unfolding events in other countries,”
they concluded.


“This
could include learning which mitigation strategies are most
successful.”

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