World Health Organisation (WHO) first announced the initial cases of what turned out to be Covid-19 exactly a year ago.A tweet was posted by the WHO on January 4, 2020, warning of a "cluster" of pneumonia cases had emerged in Wuhan, China.Investigations were underway to "identify the cause of this illness", it added.The virus was later named Covid-19 on February 11, before the WHO declared a pandemic on March 11.More than 85million cases have now been reported around the world, according to data from the Johns Hopkins University.The global death toll has reached more than 1.8million, its figures show.Last year, the World Health Organisation tweeted: "China has reported to WHO a cluster of #pneumonia cases —with no deaths— in Wuhan, Hubei.