Differences between Pfizer and Moderna vaccines Haley Hernandez, Health Reporter Tags: Here’s how they’re similar: They both need two doses. Pfizer administered 21 days apart, Moderna will be 28 days. You cannot get the first dose of one and the second of another. You have to receive the same drug and the CDC is helping to make sure everyone keeps track of when you get what with a small card you can carry for your records. Asymptomatic efficacy still to be determined: “The vaccine prevents disease at 95% rate but it prevents getting the coronavirus without disease, about 50% of the time,” Dr. Thomas Giordano from Baylor College of Medicine explained when asked about Pfizer. “It’s a lot better than 0% of the time, which is what it is if you have no vaccine. But that’s one of the reasons actually why we recommend that even after vaccination we still need to wear a mask because you could still get infected with coronavirus, not know it, you’re more likely to be asymptomatic not get sick, but still give it to someone else.”