- The first case of novel coronavirus was reported in Wuhan, China, in late December.
- The virus has since infected roughly 5.2 million people around the world and killed more than 335,000.
- It also spread to at least 185 countries and regions around the world in nearly five months.
- Here is a timeline of some of the most significant events and moments of the pandemic.
- Visit Business Insider's homepage for more stories.
December 31, 2019: Chinese Health officials informed the World Health Organization about a cluster of 41 patients with a mysterious pneumonia. Most were connected to the Huanan Seafood Wholesale Market, a wet market in the city of Wuhan.
Though the first 41 cases were reported December 31, some reporting suggests the virus could have started spreading as early as late November. The large gathering of people at the market may simply have boosted the transmission.
Researchers think the coronavirus originated in bats, then jumped to an intermediary species that passed it to people. It can be spread among humans via respiratory droplets within 6 feet. The virus can also survive for days on some surfaces.
Its pneumonia-like symptoms include fever and coughing.
January 20: The first US case was reported: a 35-year-old man in Snohomish County, Washington.
The man left Wuhan and landed at the Seattle-Tacoma International Airport on January 15. Though he initially showed no symptoms, he reported to an urgent care clinic with symptoms of pneumonia on January 19. He was diagnosed with the virus a day later.
January 30: The WHO declared a "public-health emergency of international concern."
Those instances were the Ebola outbreak that started in 2013 in West Africa, another one that's been ongoing in the Democratic Republic of Congo since 2018, the 2016 Zika epidemic, polio emerging in war zones in 2014, and the swine-flu pandemic in 2009.
January 31: President Trump banned foreign nationals from entering the US if they had been in China within the prior two weeks.
February 6: A person in California died from COVID-19, the first known American death.
California's Santa Clara County found via autopsies that three people who died in their homes on February 6, February 17, and March 6, tested positive for the coronavirus.
Before these cases were identified, officials thought that a fatality reported in Washington state on February 29 was the earliest US death from the coronavirus.
February 9: The death toll in China surpassed that of the 2002-2003 severe acute respiratory syndrome (SARS) epidemic, which killed about 774 people globally.
Both SARS and the new coronavirus come from the same family of viruses, and they share 80% of their genetic codes.
SARS emerged in Guangdong and infected 8,098 people globally over the course of eight months from 2002-2003. Just a month after the first confirmed case of the novel coronavirus, the total global case count surpassed that of SARS. On February 9, the death toll from COVID-19 in China alone exceeded the total number of people killed worldwide by SARS.
February 14: A Chinese tourist who tested positive for the virus died in France, becoming Europe's first death tied to the outbreak.
February 21: COVID-19 cases spiked in Italy.
The country's coronavirus caseload skyrocketed at the end of February — more than 110,000 people were infected at the time. Italy overtook China as the country with the most cases at the end of March, but Brazil, Russia, Spain, the UK, and the US have since surpassed it.
As of May 22, Italy has over 228,000 cases and 32,000 deaths.
February 29-March 19: Nearly all US states declared a state of emergency.
The strategic announcements can help states activate emergency response plans and spend more money on preparedness actions. Such declarations also authorize leaders to use funds to deploy additional personnel, buy equipment, and prepare stockpiles.
March 9: Italy placed all 60 million of its residents on lockdown.
The country initially saw two regions near Milan and Venice in the north become hotspots for cases, so locked down almost a dozen towns in them on February 23.
The country's leadership shut down schools, museums, and public venues, and discouraged large gatherings.
Then on March 9, the government expanded the coronavirus restriction zone to encompass the entire nation. All stores closed, save for grocery markets and pharmacies.
March 11: The WHO declared the outbreak a pandemic.
The WHO made the designation based on the geographic spread of the disease, the severity of illnesses it causes, and its effects on society.
"Pandemic is not a word to use lightly or carelessly," WHO's director-general, Tedros Adhanom Ghebreyesus, told reporters at a press briefing announcing the determination.
March 13: Trump declared a national emergency in the US.
The declaration triggered the Stafford Act and allowed for more federal aid to states and municipalities. Trump said his decision would open up access to $50 billion in aid money for US states and territories.
Meanwhile, Congress passed a roughly $2 trillion stimulus package to boost the economy.
March 19: China reported no new locally spread infections for the first time since the pandemic began.
March 26: The US became the world leader in confirmed cases with 82,404, surpassing China's 81,782 and Italy's 80,589.
March 31: More than one-third of humanity was under some form of lockdown.
India, China, France, Italy, New Zealand, Poland, and the UK implemented the world's largest and most restrictive mass quarantines.
April 2: The world passed 1 million COVID-19 infections.
April 7: Roughly 95% of all Americans were under some form of lockdown as a result of state, county, or city orders.
Governors in 42 states took the unprecedented steps of issuing "stay at home" orders by the end of March, affecting a total of 308 million people, or about 95% of the US population.
April 10: The global death toll surpassed 100,000.
April 14: President Trump ordered a halt on $400 million in US funding for the World Health Organization.
During a White House press conference, Trump blamed the WHO for "severely mismanaging and covering up the spread of the coronavirus," and said the US would end its annual contribution — which was $418 million in 2018 — to the organization.
"The WHO failed to adequately obtain, vet, and share information in a timely and transparent fashion," Trump said.
Jack Chow, a former WHO assistant director-general, told Business Insider that cutting WHO funding would be a "profound mistake." He said the move may mean "the pandemic could last for many more months, even years, longer, and could even become permanent among human populations."
May 11: Many countries, including Spain, Iran, Italy, Denmark, Israel, Germany, New Zealand, and Thailand, began to ease lockdown restrictions.
May 21: The number of global COVID-19 cases surpassed 5 million.
Do you have a personal experience with the coronavirus you'd like to share? Or a tip on how your town or community is handling the pandemic? Please email email@example.com and tell us your story.
Get the latest coronavirus business & economic impact analysis from Business Insider Intelligence on how COVID-19 is affecting industries.