In the early days, no one had fully appreciated just how infectious the virus was.
People that fell sick were transmitting the disease long before the symptoms developed.
The mortality rate for the infected was much higher than anyone had ever seen before.
People went into hospital struggling to breathe and did not come back.
Scientists said they believed the virus was a mutation from a non-human virus that had 'jumped' from another animal.
They had yet to pinpoint the source or how it had be.
