NEW YORK, NEW YORK - MARCH 26: A pharmacist prepares the Pfizer vaccine at a pop-up vaccination clinic in Chinatown on March 26, 2021 in New York City. In an effort to get more New Yorkers vaccinated against COVID-19, New York City has opened a series of pop-up vaccination sites. Many of the hubs have been placed in areas that are best to address socio-economic disparities. (Photo by Spencer Platt/Getty Images)
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NEW YORK, NEW YORK - MARCH 26: A pharmacist prepares the Pfizer vaccine at a pop-up vaccination clinic in Chinatown on March 26, 2021 in New York City. In an effort to get more New Yorkers vaccinated against COVID-19, New York City has opened a series of pop-up vaccination sites. Many of the hubs have been placed in areas that are best to address socio-economic disparities. (Photo by Spencer Platt/Getty Images)
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BARTLETT, ILLINOIS - MAY 01: Seven-year-old Hamza Haqqani, a 2nd grade student at Al-Huda Academy, uses a computer to participate in an E-learning class with his teacher and classmates while at his home on May 01, 2020 in Bartlett, Illinois. Al-Huda Academy, an Islam based private school that teaches pre-school through the 6th grade students, has had to adopt an E-learning program to finish the school year after all schools in the state were forced to cancel classes in an attempt to curtail the spread of the COVID-19 pandemic. (Photo by Scott Olson/Getty Images)
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LOS ANGELES, CALIFORNIA - APRIL 21: A man is asked to cough into his arm as part of testing for COVID-19, by a member of the Los Angeles Fire Department wearing personal protective equipment (PPE) in Skid Row, amidst the coronavirus pandemic on April 21, 2020 in Los Angeles, California. 43 people tested positive for COVID-19 at one nearby Skid Row homeless shelter. (Photo by Mario Tama/Getty Images)
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CNN  — 

Ian Haydon helped test Moderna’s coronavirus vaccine last year. Now, he’s helping test the tweaked version of that vaccine designed to fight a new, more contagious variant.

“A year ago I tried the Moderna vaccine to see if it was safe. (Spoiler: It is!) Now, on my #COVIDvaccine anniversary, I’m happy to share that I just got a 3rd dose. This booster experiment will reveal (1) if strain-adapted vaccines boost immunity & (2) whether they are safe,” Haydon, a communications specialist at the University of Washington, said via Twitter last Saturday.