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Vaccinating a high percentage of the population against COVID-19 is a crucial part of the U.S. strategy to curb the pandemic.
Since COVID-19 vaccine distribution began in the United States on Dec. 14, more than 312 million doses have been administered, fully vaccinating over 146 million people or 44.1% of the total U.S. population.
Explore how the vaccine rollout is going in the following five graphics, built using data from the Centers for Disease Control and Prevention.
Currently, two of the three COVID-19 vaccines that have been authorized for emergency use require a two-shot regimen to reach full vaccination. The third vaccine requires just one shot.
How have vaccination rates changed over time?
After a slow kickoff in December, vaccine administration improved in scale and efficiency. The country surpassed President Biden's initial goals of getting 100 million vaccines into arms in his first 100 days, reaching 200 million vaccines by day 92.
Administration rates peaked in early April — with the United States giving out more than 3 million COVID-19 shots per day — but have declined since, once people who were most eager to get vaccinated received their shots.
Vaccine eligibility opened across the country to everyone 16 and up in the U.S. in mid-April, and expanded to kids as young as 12 in mid-May. On May 4, Biden set a goal of getting a vaccine to 70% of adults in the U.S. by July 4.
Looking ahead: Projected dates for vaccination coverage
Researchers have estimated that around 70% to 85% of the country needs to be immune to the coronavirus for COVID-19 to stop spreading through communities and peter out.
People who have recovered from a coronavirus infection may have existing protection against reinfection. However, it's unclear how strong this natural immunity is and how long it lasts, so public health officials recommend that all adults get vaccinated against the disease, including those who were previously infected.
States progress unevenly in vaccine rollout
In the race to vaccinate their residents, some states with smaller populations have been leading the way.
States receive vaccine allocations based on their total adult populations. Each state has its own plan for how to get those vaccines out to its residents — through county health offices, hospital systems, pharmacies, mass vaccination sites and mobile clinics — and some states are making more efficient use of their supplies than others.
The federal government has started to play a larger role in distribution by sending vaccines directly to some pharmacy chains, community health centers and Federal Emergency Management Agency-supported sites.
The Biden-Harris administration worked to increase the supply of vaccines, trained vaccinators and places to give them out. As of April 19, anyone in the U.S. 16 and older is eligible to get a vaccine.
Selena Simmons-Duffin, Ruth Talbot, Thomas Wilburn and Carmel Wroth contributed to this report.