Two years of covid-19: How the pandemic has unfolded so far, what we’ve learned, and the questions that remain

It’s now been two years since Chinese authorities first informed the World Health Organization about an unknown virus in Wuhan. How has our understanding of the virus changed since then and where does that leave us?

By Helen Thomson

On 31 December 2019, Chinese authorities informed the World Health Organization (WHO) about a cluster of “viral pneumonia” cases of unknown cause in the city of Wuhan. Two years later, the coronavirus now known as SARS‑CoV-2 has resulted in at least 5.3 million deaths. As the world awaits the full impact of the new variant omicron, New Scientist looks back at the phenomenal scientific endeavour across the pandemic, and at how much we now know about the …