The mutation of COVID-19 seen in the United Kingdom — and emerging in the United States — is about twice as transmissible, while the South African variant that has not yet been detected in the U.S. is linked in early studies to a “diminution in what would be the efficacy of the vaccine-induced antibodies,” Dr. Anthony Fauci said.
The National Institute of Allergy and Infectious Diseases director told reporters at Thursday’s White House press briefing that the mutated UK strains are present in about 20 states and “most of the mutations don’t have any physiological relevance with regard to the function of the virus itself.”
“However, every once in a while you get mutations either singly or clustered in combinations, which do have an impact,” he said.
Fauci said that the greater transmissibility “doesn’t seem to make the virus more virulent or have a greater chance of making you seriously ill or killing you; however, we shouldn’t be lulled into complacency about that because if we have a virus that is more transmissible, you are going to get more cases, when you get more cases you are going to get more hospitalizations, and when you get more hospitalizations you are ultimately going to get more deaths.”
He noted that mutations can interfere with the efficacy of the monoclonal antibodies that are being used for treatment and prevention in some cases.
“Since the monoclonal antibodies bind to a very specific part of the virus when there’s a mutation there it has much greater a chance of obliterating the efficacy of a monoclonal antibody, and we are seeing in the much more concerning mutations that are in South Africa and in some respects Brazil, which is similar to South Africa, that it is having an effect on the monoclonal antibodies,” he added.
Fauci said the reduction in antibodies seen in studies that have not yet been peer-reviewed “does not mean that the vaccines will not be effective.”
“There is a thing called a cushion effect, so if you have a vaccine like the Moderna and the Pfizer vaccine that can suppress the virus at a dilution let’s say of 1 to 1000, and the mutant influences it by bringing it down to may be 1 to 800 or something like that you are still well above the line of not being effective,” he explained. “So there’s that cushion that even though it’s diminished somewhat, it still is effective. That is what we are seeing both certainly with the UK, which is very minimal effect. We are following very carefully the one in South Africa which is a little bit more concerning but nonetheless not something that we don’t think that we can handle.”
Fauci stressed that that concern gives “all the more reason why we should be vaccinating as many people as you possibly can because as long as the virus is out there, replicating viruses don’t mutate unless they replicate, and if you can suppress that by a very good vaccine campaign, then you can actually avoid this deleterious effect that you might get from the mutations.”
“Bottom line, we are paying very close attention to it; there are alternative plans if we ever have to modify the vaccine,” he said. “That is not something — that is a very onerous thing — we can do that given the platforms we have, but right now from the reports we have literally as of today it appears that the vaccines will still be effective against them with the caveat in mind you want to pay close attention to it.”
Fauci also cautioned that although it “does not appear at all” that the South African strain is in the United States, “we must be honest and say that the level of comprehensive sequence surveillance thus far is not at the level that we would have liked.”
As far as the strain first seen in the UK, which has been crossed the pond to the U.S., “the real question that’s going to be asked, is it going to become the dominant strain or will the strains we already have prevent it from flourishing and being the more dominant strain?”