RELATED: Moderna Just Made This Major Announcement About Its COVID Vaccine. On Sept. 21, Johnson & Johnson released new data on its vaccine’s efficacy and potential boosters, and the company’s Global Head of Research and Development Mathai Mammen, PhD, broke down some of the key aspects of the findings in an interview with Good Morning America. “[The] single-shot gives strong and long-lasting protection out past six months with no evidence at all of waning effectiveness,” Mammen said. He added that “what distinguishes the J&J vaccine is its long-lasting nature. The nature of the vaccine has the right kind of immune response to lead to that long-lasting effect.” While Moderna reported that its mRNA vaccine remained 93 percent effective through six months, the data on the Pfizer vaccine has been slightly less promising. In June, the company’s CEO said the Pfizer vaccine was 84 percent effective against COVID after six months. Then, in a July announcement, Pfizer cited a study from the Israel Ministry of Health that found that vaccine efficacy “in preventing both infection and symptomatic disease has declined six months post-vaccination.” Most recently, in August, data out of the U.K.’s ZOE COVID study found that after five to six months, the effectiveness of the Pfizer vaccine fell to 74 percent. RELATED: For more up-to-date information, sign up for our daily newsletter. Early on, medical experts speculated that a Johnson & Johnson booster shot would be needed sooner than the other vaccines since its efficacy was lower initially and while that might not be true, Johnson & Johnson’s new data showed that a booster can get its vaccine’s effectiveness up to the initial levels provided by Pfizer and Moderna. According to the new data, 28 days after your first dose, the vaccine is about 74 percent efficacious at protecting you from severe COVID, but a booster shot at six months would bump the vaccine’s efficacy up to 94 percent against symptomatic COVID in the U.S. Mammen said researchers and executives at Johnson & Johnson were “very happy” about these findings. “We were bouncing out of our chairs when we saw these data,” he said on Good Morning America. Over the summer, as the Delta variant surged, some experts, including Angela Rasmussen, PhD, a virus expert and research scientist with the Vaccine and Infectious Disease Organization (VIDO), encouraged people who got the one-dose vaccine to get another shot from a different company. “If you are in the U.S. and got J&J, I encourage you to talk to your provider about whether this is something you should think about. If you live in a community with overall low vaccination, I’d suggest you strongly consider doing so,” she tweeted on June 22. She added that a second dose of an mRNA vaccine, like Pfizer or Moderna, might be more likely to provide protection as the Delta variant spread. RELATED: Dr. Fauci Warns You Not to Do This If You Got Moderna or J&J.ae0fcc31ae342fd3a1346ebb1f342fcb However, the CDC and FDA have not recommended mixing vaccines. “There aren’t enough data currently to support getting an mRNA vaccine dose (either Pfizer-BioNTech or Moderna) if someone has previously gotten a J&J/Janssen vaccine,” the CDC says on its website, which was last updated Sept. 1. “People who got the J&J/Janssen vaccine will likely need a booster dose of the J&J/Janssen vaccine, and more data are expected in the coming weeks. With those data in hand, CDC will keep the public informed with a timely plan for J&J/Janssen booster shots.” Right now, only the Pfizer vaccine is approved for boosters (and not for the general public), a ruling the FDA came to on Sept. 17. “People who get J&J will be coming in asking to get Pfizer and Moderna, etc.,” Anthony Fauci, MD, the White House’s chief COVID-19 adviser, told CNN on Sept. 19. “Theoretically, if you look at things, it is very unlikely that there’s going to be a risk there. But, scientifically, you don’t want to go by unlikely. You want to have some scientific proof. And that’s the reason why, right now, we recommend that people go by the guidelines according to the FDA approval and the CDC recommendations.” Once Johnson & Johnson submits its booster data for review, it will also be considered byt the FDA. A ruling on a Moderna booster is expected in the next few weeks as well. “We fully anticipate that, within a period of a couple to three weeks, that there will be enough information on the data that will be presented to the FDA by J&J and by Moderna that we’ll be able to proceed and get those data analyzed to be able to move with the booster in those categories,” Fauci told CNN. “We don’t believe it’s going to be a considerable period of time.” On Good Morning America, Mammen assured viewers that Johnson & Johnson remains protective for a long time, but noted how much a booster can help. “For those that need or want additional protection, a second shot at six months ideally really raises that level of protection,” he said. He added that the timing of when Johnson & Johnson recipients will be eligible for a booster shot is ultimately up to the regulatory agencies, the CDC and FDA. RELATED: Pfizer Just Said Doing This “Strongly” Boosts Protection From Delta Variant.