The world might be gearing to come out of lockdown,
but the threat of coronavirus hasn't gone away.
Anyone who hasn't yet had the disease
is just as susceptible to catching it now
as they were before, and no country in the world
has yet achieved herd immunity, where so many of the population
have been infected that the risk of infection to others
becomes very low.
And while lifesaving drugs may have hit the news recently,
with one called Remdesivir being given emergency authorisation
in the US, no drug has yet been shown to improve the survival
chances of Covid patients.
Only a vaccine can allow us to get back to normality.
And realistically, that's going to take at least until 2021.
Until then, stopping the transmission of coronavirus is
the only defence we have.
Some countries have seen the reproduction
number, the fabled R number, fall below one.
This is critical for disease control.
If R is two, then 10 infected people
will, on average, pass the disease on to 20 more,
and the epidemic grows exponentially.
If the R is 0.5, those 10 infected people
will only infect another five, and the epidemic gradually
declines.
The problem is the lockdowns that
are keeping R below one on not seen as sustainable,
both for economic and long-term health and social reasons.
So how can governments free up economies
while keeping Covid-19 under control?
In the absence of any certainty, different countries are taking
different approaches, but most are favouring the basic
principle of testing, tracking, and tracing.
That allows public health officials
to know where the virus is and how it's spreading
so it can be contained.
South Korea has used this technique
since the start of the pandemic.
It relies on the population using
a smartphone app that can track any individual's location.
If that individual then comes into close contact with someone
who later tests positive, the app will alert them
and they can, in turn, get tested and self-isolate.
Apps designed to track and trace are not without their problems,
though.
In order to work effectively they
need the majority of the population
to download and use them, and many
have data privacy concerns.
It's also unclear whether those who've been close to someone
with the virus should be forced to isolate.
Those living and working in busy areas,
like cities, could end up bouncing from one period
of isolation to another.
Another idea is to give people immunity certificates
or immunity passports, which would exempt workers
from lockdowns because they've already had the virus.
But until we really understand the link between antibodies
and immunity, the World Health Organisation
has warned against countries adopting this approach.
Sending people who have already had
the virus back into circulation could pose an infection risk.
When it comes to relaxing restrictions
some countries are trying a more nuanced approach
which doesn't treat the entire population as a uniform blob.
France has opted to divide the country
into red and green zones, which have slightly different rules.
Red zones, which include Paris, are
where the virus is still circulating
and the burden on intensive care units is high.
So parks, for example, can reopen in green zones but not
red ones.
There is also a discussion on whether there
should be different rules for young and old or at-risk
groups.
Medically speaking, the young are
the least at risk from the virus but possibly the hardest
hit by lockdowns, in terms of lost education and work.
Each country will end up choosing
its own distinctive path out of lockdown.
Whether a government decides to reopen schools and restaurants
or to allow more contact between households
will depend on many things.
Its capacity to track and trace, how old its population is,
and its mix of urban and rural communities.
There may also be cultural considerations.
But for now, as we wait for a vaccine, keeping R down
while society finds some kind of new normal is the only approach
any nation can take.