• The Food and Drug Administration said Monday that modified Covid-19 vaccines against new, emerging variants may be authorized without the need for lengthy clinical trials.
• A drugmaker would need to submit new data that shows the modified vaccine produces a similar immune response and is safe, similar to the process for annual flu vaccines.
• U.S. health officials, including White House Chief Medical Advisor Dr. Anthony Fauci, are concerned the virus could mutate enough to evade the protection of current vaccines and reverse the progress made on the pandemic.

The Food and Drug Administration said Monday that modified Covid-19 vaccines against new, emerging variants may be authorized without the need for lengthy clinical trials.

The new guidance, released in a 24-page document on the FDA's website, would clear the new vaccines as an amendment to a company's originally approved emergency use application, according to the FDA. The company would need to submit new data that shows the modified vaccine produces a similar immune response and is safe, similar to the process for annual flu vaccines.

"Preliminary reports from clinical trials evaluating COVID-19 vaccine candidates in multiple countries including South Africa have added to concerns that vaccine efficacy against the B.1.351 variant may be lower than against the original virus," the agency wrote in the document, referring to the strain found in South Africa. "Thus, there is an urgent need to initiate development and evaluation of vaccines against these SARSCoV-2 variants."

The updated guidance comes as U.S. health officials, including White House Chief Medical Advisor Dr. Anthony Fauci, are concerned the virus potentially could mutate enough to evade the protection of current vaccines and reverse the progress made on the pandemic.

In recent weeks, officials have pushed Americans to get vaccinated as quickly as possible before potentially new and even more dangerous variants of the virus emerge.

As of Sunday, the Centers for Disease Control and Prevention has identified 1,661 cases of the B.1.1.7 variant, first identified in the U.K. The agency has identified 22 cases of the B.1.351 strain, from South Africa, as well as five cases of P.1, a variant first identified in Brazil.

The FDA authorized Pfizer's and Moderna's vaccines for emergency use in December, and the two drugmakers have since announced plans to modify their shots to target new variants. The guidance could accelerate the regulatory review process for the vaccines.

Public health officials and infectious disease experts have said there is a high likelihood that Covid-19 will become an endemic disease, meaning it will never fully go away, though it will likely spread at lower levels than it is now. Health officials will have to continuously watch for new variants of the virus, so scientists can produce vaccines to fight them, medical experts say.

Richard Webby, who directs a World Health Organization flu center at St. Jude Children's Research Hospital, said the clearance process for modified Covid-19 vaccines may end up being very similar to the process for annual flu shots.

The U.S. and other nations will need to ramp up their surveillance of new strains and then make periodic recommendations on which variants the shots should target, he said in a recent interview. "For Covid, that's not there right now."