Controlling the virus
SARS COV-2 is the cousin of the SARS virus which was first discovered in China in November 2002. SARS spread around much of the world infecting about 8,000 people and was much more aggressive than SARS COV-2 killing about 1 in 10 people who were infected. The level of Infections peaked in May 2003 but the virus had disappeared by July. However, unlike SARS COV-2 most patients showed symptoms within 2-3 days and were only infectious when they had these symptoms. This made the virus much easier to control as it was possible to tell who had the disease and quarantine them.
Although SARS COV-2 shares 80% of the RNA genome with SARS it is less aggressive, however it has spread faster and further around the world as people can be infectious without any symptoms making it very difficult to control.
Countries around the world have applied many of the same techniques to control the new SARS COV-2 starting with lockdown. On Tuesday 24th March India locked down 1.3 billion people resulting in more than a third of the worlds 7.8 billion people being under some kind of lockdown.
This map shows the various lockdown measures around the world. Full lockdown is a 24 hour restriction on movement. Partial is where the country has citizens restricted for only part of the day. In green there may be other restrictions but citizens can move around.
During April approximately one third of the world were locked down to some degree. In addition to lockdown and particularly when countries begin to ease the lockdown they have a number of different measures they can use to control the virus. These are:
Tracking and tracing the virus using contract tracers and apps
Constant testing for the virus
Partial lockdown by area or business/activity
The speed and degree to which these have been applied, in particular lockdown is thought to have affected the number of cases and deaths in each particular country.