Travel was suspended from Europe, the NBA and college basketball was shut down and Illinois would close all non-essential businesses, within days.
"We have therefore made the assessment that COVID-19 can be characterized as a pandemic," said WHO Director-General Dr. Tedros Adhanom Ghebreyesus, one year ago.
The entire world changed. Since then, there have been more than 100 million confirmed cases of coronavirus and over 2.6 million deaths globally.
Here in Illinois, over 1.2 million cases have been reported, with over 20,000 confirmed deaths.
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"It was exactly one year ago this morning that I said things are going to get much worse before they get better but I did not realize in my mind even anything close to more than half a million people having died in this country," said Dr. Anthony Fauci.
Some longtime businesses have shut down and Soldier Field, Wrigley and Sox park were void of fans. Both O'Hare and Midway airports looked like ghost towns, flourishing areas of the city like downtown were deserted and schools moved to remote learning. We've seen three infection surges, forcing restriction changes, and now all eyes are on predominant COVID-19 variants popping up.
But more Americans are getting vaccinated every day. In Illinois, according to IDPH, over 3.5 million doses have been administered, and mass vaccination sites continue to pop up all across our area- things are finally slowly starting to improve.
And three extremely effective vaccines are available one year after COVID-19 was declared a pandemic, showing how quickly science has progressed considering how little doctors knew about the virus last March.
WATCH | Doctors share lessons learned in 1st year of COVID-19 pandemic
"First, it looked like it was somewhat similar to the flu then it became apparent, it was more contagious than the flu," said Dr. Richard Novak, UIC Hospital Infectious Disease Director.
As Chicago hospitals began filling up with COVID patients last March, front line doctors learned quickly how to treat the virus and how it spreads.
"We had the fear at the beginning: are you going to get it from touching door handles, are you going to get it from touching surfaces from delivery? What we know is: it's airborne," said Dr. John Coleman, Northwestern Medicine Pulmonary Critical Care Specialists.
With transmission through aerosol droplets, masks became one of the best ways to prevent infection. As for treating patients, doctors learned therapeutics like Remdesivir and steroids were more effective than some traditional ICU methods.
While doctors have learned a lot about the coronavirus in the past year, there is still a great deal they don't know, especially when it comes to long-term health effects and immunity.
"We don't know how long immunity lasts if you get COVID," Coleman said. "We don't know if you have immunity to COVID, do those antibodies protect you from different variant."
"It's clear a number of people suffer long-term consequences and we don't know a lot about those," Novak said. "We need to learn what causes it."
Novak and Coleman said there is a lot more learning to do after all COVID is only a year old, and they say it's likely to be around for a long time.
"It's been a time I'll never forget," Dr. Citronberg said. "Last year around this time we were just getting started, great learning experience not only from a medical point of view but also just personal reflection and growth."
Health officials remind us to stay vigilant and continue protocol. It's not a time to let our guard down.
"With a continuation of public health measures and a gradual pulling back as opposed to a just turning a light switch on and off," Dr. Fauci said. "We've got to gradually and prudently pull back as we get closer and closer to normal."