"The mutants are here," Dr. Anthony Fauci, the chief medical advisor to the President and the director of the National Institute of Allergy and Infectious Diseases, warned this week. He was speaking about the variants of COVID-19 that are more transmissible—and possibly more deadly. "These variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19," says the CDC. "An increase in the number of cases will put more strain on health care resources, lead to more hospitalizations, and potentially more deaths." Fauci spoke with Ari Melber on MSNBC about the "worse case scenario." Read on to heed his warning—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus. Dr. Fauci Said The Worst Case Scenario "Is a Possibility" Melber asked Fauci about the variants—"you have the South African one, that's getting attention because it's seen as more infectious and resistant to vaccines," he said. "Meanwhile, a top epidemiologist who advises Joe Biden is offering this warning about the British strain today." The epidemiologist Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said a "Category 5 hurricane" could be on our way. "It's going to take much more than vaccine to keep this variant at bay and not to have potentially a major surge in just the weeks ahead," Osterholm said on CNN's New Day. "I think amongst my colleagues, they would agree that this variant from the United Kingdom, which is now beginning to circulate much more widely in the United States, poses a huge challenge to us. And that in just a few weeks, we could be seeing case numbers increase very dramatically," Osterholm added. "Well, let's put it this way: Certainly that is a possibility," said Dr. Fauci. "But" if we all follow the pubic health measures and get vaccinated, "that doesn't necessarily have to happen," he says. Fauci said his "good friend" Dr. Osterholm "tends to think in terms of the worst case scenario. Now the worst case scenario may occur. But I think we have the power within us to do things, to prevent that from occurring. So if you get a dominant strain and he's quite correct in saying that if you do modeling the UK strain, which shows to be more transmissible in the UK, leading to this surge—if it becomes dominant in the United States, we will be challenged with a virus that has a degree of transmissibility. That's more efficient than what we've been dealing with. And because of that, that should be an impetus for us to double down. So that uniformly—not spottily, but uniformly throughout the country—that we do have a degree of adherence to those measures that we know work. So he's correct in saying that this is a possibility and it might be, but I think it doesn't have to be an inevitability—a possibility, but not necessarily an inevitability." RELATED: 7 Tips You Must Follow to Avoid COVID,