A Timeline of COVID in the U.S.: One Year Since the First Case Was Identified

January 21, 2021 marks one year since the novel coronavirus was first confirmed in the United States.

The virus was first identified in Wuhan, China, in late 2019 before it began spreading around the world. While the U.S. and other countries initially restricted travel in an attempt to block the virus' arrival, some experts believe the virus actually began spreading in the U.S. before health officials confirmed the first known American patient.

The first identified U.S. case was reported in a patient living in Washington state. During the 12 months since, health officials across the country have reported more than 24.3 million cases, and more than 400,000 Americans have died after contracting the virus, according to a Johns Hopkins University data tracker. The virus has infected more than 96 million people and killed more than 2 million across the globe, the data tracker shows.

The response to the pandemic in the U.S. quickly became politicized as lawmakers on both sides of the aisle took positions on wearing masks and imposing lockdowns in efforts to prevent further spread of the virus, which health officials now know is highly transmissible. While international agencies like the World Health Organization (WHO) have encouraged social distancing, wearing masks and other precautionary measures, protests abounded in the U.S. and in other parts of the world as people reacted to the social and economic pressures brought about by the pandemic.

Below is a timeline of the pandemic in the U.S. since health officials identified the country's first case one year ago.

A Timeline of the Coronavirus Pandemic in the U.S.

January 21, 2020: The Centers for Disease Control and Prevention (CDC) announced the first case of the virus was identified in Washington state. The CDC said the individual arrived home on January 15 after traveling to Wuhan and shortly thereafter sought medical treatment. A specimen sample sent to the CDC, which warned health officials to be on the lookout for the virus one week earlier, confirmed the patient was ill with the virus.

February 2, 2020: A travel ban former President Donald Trump announced on January 31 went into effect for individuals traveling to the U.S. from China. Americans who were visiting China at the time of Trump's proclamation were required to quarantine after returning home.

February 29, 2020: The CDC confirmed the country's first COVID-19-related death in a virus patient in Washington state. The agency identified the patient as a man in his 50s.

March 11, 2020: Trump announced an expansion of the travel ban that went into effect in early February to include several European countries. The temporary ban went into effect on March 13.

March 13, 2020: Trump declared a national emergency in connection with the virus, which the WHO classified as a pandemic on March 11. On January 31, the Department of Health and Human Services (HHS) said the threat of the virus constituted a public health emergency. Trump referenced the HHS' public health emergency declaration in his proclamation, which granted the head of the HHS emergency authority to temporarily waive requirements for specific insurance programs, including Medicare and Medicaid.

March 19, 2020: California Governor Gavin Newsom became the first state leader in the U.S. to introduce a statewide stay-at-home order in response to the virus' spread. New York Governor Andrew Cuomo followed suit the next day, and most other governors similarly issued stay-at-home orders in the months that followed. Though New York quickly emerged as the state with the greatest number of COVID-19 cases during the early months of the pandemic, California has since passed the records New York set and currently leads the U.S. in terms of total reported cases.

March 27, 2020: Trump signed an economic stimulus bill known as the Coronavirus Aid, Relief, and Economic Security (CARES) Act into law two days after the bill passed in the Senate. The relief package included assistance for Americans struggling during the pandemic, including one-time stimulus payments for qualifying citizens and financial support for businesses that applied for help.

March 28, 2020: The Food and Drug Administration (FDA) issued an emergency use authorization for hydroxychloroquine, a drug commonly used to treat malaria, in the treatment of COVID-19 patients. The FDA later revoked its emergency use authorization for hydroxychloroquine and chloroquine on June 15 after use of the drugs in hospitalized patients did not appear to improve the patients' outcome. On July 1, the FDA added that use of hydroxychloroquine had been connected to "serious heart rhythm problems and other safety issues."

April 3, 2020: The CDC recommended that all Americans wear facial coverings when social distancing was not possible due to the risk of virus spread. Though the agency recommended face mask use, federal health officials did not require Americans to wear them, and Trump largely avoided wearing masks in public.

April 28, 2020: A Johns Hopkins University data tracker showed the U.S. exceeded 1 million total cases since the first American COVID-19 patient was identified three months earlier.

May 1, 2020: The FDA issued another emergency use authorization for remdesivir, an antiviral drug that some health officials believed might be useful in the treatment of COVID-19. The emergency use authorization was issued two days after the National Institutes of Health published a positive assessment of the drug based on its clinical trial.

May 15, 2020: The Trump administration announced "Operation Warp Speed," a project intended to support the development of COVID-19 vaccine candidates. The initial goal of the project was to develop at least one vaccine and begin administering it to Americans before the end of 2020.

May 28, 2020: Three months after confirming the first virus-related death in the U.S., the CDC said at least 100,000 Americans had died after contracting the virus. In a news release, the agency referred to the death toll as a "sobering development" and said it served as a "heart-breaking reminder of the horrible toll of this unprecedented pandemic."

July 7, 2020: Trump announced that the U.S. was officially withdrawing from the WHO after saying in May that he planned to halt funding to the organization. The withdrawal was to take effect on July 6, 2021, though President Joe Biden said he intended on reviving the country's relationship with the WHO once he took office.

July 14, 2020: The CDC issued stronger recommendations to wear masks as a strategy for preventing the spread of COVID-19. Then-CDC Director Robert Redfield identified masks as "one of the most powerful weapons we have to slow and stop the spread of the virus" in a news release from the agency.

September 23, 2020: The HHS announced $200 million in funding to help states with future vaccine distribution. Though no pharmaceutical company had yet filed for emergency use authorization, promising clinical trials signaled that a handful of companies may have been close to doing so.

October 2, 2020: As new infections began rising throughout the U.S. in what health officials called the "second wave," Trump announced that he too had tested positive for the virus. The announcement triggered a discussion about leadership within the executive branch as Trump faced a virus that had at that point resulted in more than 200,000 American deaths. In the weekend following his announcement, Trump was taken to a military hospital for treatment and shortly thereafter returned to the White House. A White House physician monitored Trump's symptoms in the days that followed and Trump was eventually declared recovered.

November 8, 2020: More than 10 million cases were reported in the U.S. since the start of the pandemic by November 8, according to The New York Times. The country reached that milestone less than two weeks after reporting 9 million total cases, thus entering a stretch in which it began reporting record numbers of new infections each week.

December 10, 2020: More Americans had died from COVID-19 by December 10 than had died in combat during World War II. The U.S. Department of Veterans Affairs identifies World War II as the deadliest war in American history in terms of soldiers who died in combat.

December 11, 2020: The FDA authorized Pfizer's COVID-19 vaccine candidate for emergency use. The vaccine's approval paved the way for states and territories to begin receiving doses for distribution.

December 14, 2020: A woman working as a critical care nurse in New York was one of the first Americans to receive a COVID-19 vaccine on December 14. Some news outlets identified her as the first American in the country to receive a vaccine. Her vaccination was live-streamed by Governor Andrew Cuomo's office and celebrated in a tweet from Trump.

December 18, 2020: The FDA authorized Moderna's COVID-19 vaccine candidate one week after the agency authorized Pfizer's. The second vaccine approval enabled health officials to begin sending additional doses for distribution throughout the U.S.

January 19, 2021: More than 400,000 Americans died after contracting COVID-19 by January 19, according to a Johns Hopkins University data tracker. The country reached the milestone on Trump's final full day in office.

January 20, 2021: Biden instituted a 100-day face mask mandate on federal property hours after his inauguration. Later that day, California also became the first U.S. state to surpass 3 million reported cases since the start of the pandemic.

Newsweek reached out to the CDC for comment but did not receive a response in time for publication.