This week marks 100 days since the World Health Organisation (WHO) received the first report of an unknown illness affecting a number of people falling ill in Wuhan, China.

Coronavirus has since claimed tens of thousands of lives across the world and been labelled a pandemic by the WHO.

But how far have we come since December 31 last year, and what do we know about Covid-19?

– What is Covid-19?

Coronaviruses are a family of viruses that cause illness in humans and animals.

Seven different types have been found in people, including those responsible for Covid-19 and the Sars and Mers epidemics.

Based on early suggestions, it is thought the current virus is more contagious than Sars, with one person infecting around three others.

Coronaviruses cause respiratory and intestinal illnesses in humans and animals.

– Where did the coronavirus come from?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the current pandemic of coronavirus disease, which was first identified in Wuhan, China, following reports of serious pneumonia.

It is thought the outbreak may have started in Huanan Seafood Wholesale Market, which sold live animals.

Covid-19 is believed to have a zoonotic origin, meaning it was active in animals before it was transmitted to humans.

Unconfirmed reports have suggested it could have originated in bats or pangolins.

– Are there any treatments or vaccinations for coronavirus?

There is no specific treatment or vaccine for coronavirus, and researchers across the world are racing to develop both.

Experts seem to be in consensus that a vaccine is the ultimate exit strategy from the disease.

It is hoped a vaccine may be given emergency approval before the end of the year, but most scientists agree that it will be around 12 months before one is widely available for use.

– When will the pandemic end?

While there are signs of the infection rates dropping in some countries like China, this follows months of lockdown that restricted people’s movement.

There are a limited number of ways out of the crisis – vaccination, enough people developing immunity through infection, or permanently changing the way we live to keep some of the measures that have been introduced in place.

A vaccine may be 12-18 months away, and it may take years for herd immunity to develop – where so many people have already been infected with Covid-19 that the virus struggles to spread.

While the UK Government insists this is not a policy aim, over time it may just become a reality.