An initial outbreak in Wuhan, China, grew into the coronavirus pandemic that has infected more than 1.4 million people and killed at least 81,000 worldwide.

From the beginning, Chinese healthcare workers scrambled to contain the virus and treat an influx of new patients while battling a lack of medical tests, a shortage of room in hospitals, and mixed messaging from the government.

To quell the outbreak, Chinese authorities ordered sweeping lockdowns throughout the country, cut-off travel for tens of millions of people, panic-built new hospitals, and initiated surveillance measures to track people with the virus.

In just four months, the virus has spread from to 184 other countries, resulting in nationwide lockdowns across the globe.

Chinese authorities began an official investigation into the disease in early January, after fear began spreading that this could be like SARS, another coronavirus that originated in China and killed 774 people in the early 2000s.

Vietnam's Vice Minister of Health Nguyen Truong Son talks with a man at an isolated section of a hospital where two Chinese citizens had tested positive for coronavirus, in Ho Chi Minh city

At this time, it was acknowledged that the virus could spread form human-to-human contact. During the early stages of the outbreak, people began wearing masks to protect themselves — even though, for the average person, wearing a mask is not as effective as hand-washing and avoiding infected people.

A woman wears a mask while riding an electric bicycle near the closed Huanan Seafood Wholesale Market.

As the death toll climbed to nine, the Chinese government urged people to avoid traveling to Wuhan and to stay away from public spaces — a warning that came just as millions of people were planning to migrate for the Lunar New Year.

Passengers wear protective face masks at the departure hall of the high speed train station in Hong Kong, Thursday, Jan. 23, 2020.

On January 25, the Chinese government barred citizens from booking overseas flights, hotels, and tours.

A worker in protective suits checks the temperature of a passenger arriving at the Xianning North Station on the eve of the Chinese Lunar New Year celebrations, in Xianning, a city bordering Wuhan to the north, in Hubei province, China January 24, 2020.

Huoshenshan Hospital was completed 10 days later, on February 3, and is located on the outskirts of the city. It has an area of 270,000 square feet, and is equipped with 1,000 beds, and 1,400 military medics of the Chinese People's Liberation Army as staff.

On January 31, the US government announced plans to bar foreign travelers from entering the US if they have traveled to China within 14 days. And the Pentagon has started preparing quarantine facilities that can hold up to 1,000 people entering the US, if necessary.

Members of the Thai Airways crew prepare to disinfect the cabin of an aircraft to prevent the spread of the coronavirus at Bangkok's Suvarnabhumi International Airport, Thailand, January 28, 2020.

By early February, Chinese authorities began using extreme measures to quell the outbreak in Wuhan, including door-to-door searches, excessive sanitation, and gathering sick people in quarantine centers.

Volunteers from the Blue Sky Rescue team disinfect at the Qintai Grand Theatre in Wuhan,

By mid-February, hundreds of thousands of Chinese workers and volunteers were positioned around the country to restrict the movement of millions of people through blocking travel, and ensuring people stay in their homes.

Cleaners wash a street in the quarantined city of Wuhan with a high-pressure water gun on February 3, 2020.

Residents are now permitted to leave Wuhan, but only if they have a mandatory smartphone application that monitors their health and determines how far they are able to travel.

In this April 1, 2020, photo, a passenger holds up a green pass on their phone on a subway train in Wuhan in central China's Hubei province. Green is the "health code" that says a user is symptom-free and it’s required to board a subway, check into a hotel or just enter Wuhan, the central city of 11 million people where the pandemic began in December. (AP Photo/Olivia Zhang)

China has officially reported 82,718 cases and 3,335 deaths as of April 7. But many believe the real numbers are much higher and suspect the Chinese government worked to conceal the actual statistics and give false information throughout the outbreak.

Public health experts worry Wuhan's reopening could trigger a second wave of infections in China. "This day does not mark the final victory," the Communist Party's flagship newspaper People's Daily said in in editorial. "At this moment, we still need to remind ourselves that as Wuhan is unblocked, we can be pleased, but we must not relax."

Travelers walk past Wuhan's Hankou railway station a day before it resumes outbound traffic.