RELATED: This Is What Experts Want You to Know About the Pfizer Booster. In statement released by the CDC on Oct. 21, patients are eligible to receive a third dose of the Moderna COVID-19 vaccine if they received a second dose of the vaccine at least six months ago and meet at least one of the following criteria: They are age 65 or older, age 18 or older and live in a long-term care setting, age 18 or older and have an underlying medical condition, or are age 18 or older and work in high-risk settings.ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: You Need a Booster Before This Date, Virus Experts Warn. According to the recently updated regulations released by the CDC, you now can receive any brand of  booster shot, no matter what vaccine you received for the first two doses. This means if you received Pfizer for the first two doses, but want to receive Moderna for the third, you may do so. Like the Pfizer booster, a third dose of the Moderna mRNA COVID-19 vaccine is identical to the first two doses, according to the experts at Johns Hopkins Medicine. The only difference is that the third dose contains half the antigen of the prior doses. Just like the initial doses of the vaccine, the Moderna booster is free, health officials have confirmed. “No ID or insurance card is required,” the AARP reported on Oct. 22. “It is, however, a good idea to bring your paper vaccination record so the date of your booster shot can be added.” Moderna booster shots will be available at health clinics, pharmacies, and other official vaccination sites, which will continue to administer initial vaccine doses as well as booster shots. And according to national health officials, supplies are stocked. “The bottom line is that we are prepared for boosters and we will hit the ground running,” Jeffrey Zients, White House coronavirus response coordinator, said in a statement, the AARP reported. According to a new CDC study, the side effects of a third shot of Moderna were similar to the ones experienced after the second dose of the vaccine, and typically less severe, CNBC reported on Oct. 21. The CDC study found that the most common side effects reported after a third dose of Moderna were nearly identical to the ones reported after the Pfizer booster. These were pain at the injection site, fatigue, muscle pain, headache, and fever, followed by chills and nausea, CNBC reported. For more helpful health information sent straight to your inbox, sign up for our daily newsletter.  While there is no word on when it will be available, Moderna announced last month that it was in the process of developing a single vaccine that would combine a booster dose against COVID-19 with the company’s experimental flu shot. “We believe this is a very large opportunity that is ahead of us, if we could bring to market a high efficacy pan-respiratory annual booster,” Moderna CEO Stéphane Bancel said during a presentation to update investors on its drugs in development, Reuters reported. “We believe Moderna could be first to market in this important new opportunity.” RELATED: Virus Experts Say If You Want a Booster, Don’t Do This Right Now.