Trump Covid vaccine czar says ‘extremely low’ chance Pfizer and Moderna shots won’t work against new strain

President Donald Trump‘s coronavirus vaccine czar said Monday that he expects Pfizer’s and Moderna’s Covid-19 shots will be effective against a new mutation of the virus found in the U.K.

The comment came after the U.K. on Saturday said it identified a new mutation of the virus that can spread more quickly than previous variants. Countries including Italy, Germany, Canada and Israel have barred flights from the U.K. following reports of the new strain.

The mutations include changes to the spike protein that the virus uses to infect human cells. The vaccines induce an immune response against several structures found around the spike protein, a multifunctional mechanism that allows the virus to enter the host, Dr. Moncef Slaoui, chief science advisor of Trump’s vaccine program Operation Warp Speed, told reporters during a press briefing. The chances one set of mutations would completely alter those structures “are extremely low,” he added.

Both Pfizer and Moderna’s vaccine use messenger RNA, or mRNA, technology. It’s a new approach to vaccines that uses genetic material – in this case, a harmless piece of spike protein – to provoke an immune response against the virus.

Word Health Organization officials on Monday reiterated that officials from the U.K. have said the new variant could be up to 70% more transmissible than the original strain of the virus. Dr. Mike Ryan, executive director of the WHO’s health emergencies program, said during a press briefing that it was unclear if the increase in spread in the U.K. is due to the mutation or human behavior.

“We’ve seen an estimate of a small increase in the reproductive number by the U.K.,” he said, meaning the virus is spreading faster, which could mean it is more contagious or spreads more easily in colder months. It could also mean people are getting lax about following public health protocols. “It remains to be seen how much of that is due to the specific genetic change in the new variant. I suspect some.”

Slaoui said he spoke with U.K. health regulators earlier Monday about the new strain. He said to date, there is no “hard evidence” the virus is more easily transmitted than the original strain of the disease.

“There is clear evidence that there is more of it in the population,” he said, adding the emergence of the new strain also be due to the fact that scientists are now able to track variants of the virus more quickly. Before U.K. scientists may have not been looking for this variant and infections happened in the “shadows” he said.

A safe and effective vaccine is seen by investors and policymakers as a solution to get the global economy back on track after the pandemic wreaked havoc on nearly every country across the globe and upended businesses.

Americans are expected to get some of the first shots of Moderna’s vaccine on Monday after the Food and Drug Administration authorized the vaccine for emergency use on Friday. The U.S. will distribute 5.9 million doses of the vaccine across the nation this week as well as 2 million doses of Pfizer’s vaccine, which was authorized for emergency use on Dec. 11, health officials said Monday.

Health and Human Services Secretary Alex Azar said Monday that the U.S. is now on the “offensive” against the virus, which has killed more than 310,000 Americans in less than a year. He said he plans to get Moderna’s vaccine “in the coming days” to demonstrate the shots are safe and effective.

–CNBC’s Will Feuer contributed to this report.