ATLANTA, Ga. (WPVI) -- The CDC released a new report showing how the spread of the virus took off in late February and early March.
Officials will use this data as they start to further lift restrictions.
Despite the seemingly long battle against the coronavirus, experts say the majority of the population in the U-S has still not been exposed and remains vulnerable to infection.
The CDC report shows what lead to acceleration of the spread of the virus in March.
It includes travel - especially passengers coming off cruise ships from both Europe and Asia, people attending professional conferences and social events.
The virus also spreading quickly and silently in high risk long term care facilities, or densely populated urban areas and work places.
What made this worse is the virus went undetected in many cases, either people didn't have symptoms or had mild symptoms and continued to be in the community.
Slow testing to identify who was infected and isolate them also lead to quick transmission.
Health officials will look at these risk factors closely as governments try to lift restrictions while still trying to control the spread.
CDC: Travel, conferences, close working and living quarters fueled spread of COVID-19