The U.S. Food and Drug Administration (F.D.A.) announced on Monday that modified coronavirus vaccines developed to protect against new, emerging variants of SARS-CoV-2 may be authorized for use without needing data from large clinical trials. This decision, similar to the annual approval of flu vaccines, helps ensure that an effective booster shot is available to soon after it is developed.

The federal health regulator stated in a 24-page document that drug developers will only need to submit data that demonstrates that a modified vaccine candidate produces a similar immune response to the vaccine's original formula and is safe for broad use. From there, the F.D.A. will approve the new vaccines with an amendment to the developer's original approved emergency use application.

The new guidance comes as global health officials have become concerned that the coronavirus will soon mutate to such a degree that already developed vaccines will not be as effective at preventing infection. Currently, it appears that the variant B.1.351, which was first discovered in South Africa, is too genetically different from the original SARS-CoV-2 strain for vaccine to protect against its infection as well as against other mutations.

"Preliminary reports from clinical trials evaluating COVID-19 vaccine candidates in multiple countries, including South Africa, have added to concerns that vaccine efficiency against the B.1.351 variant may be lower than against the orginal virus," the F.D.A. wrote in the document. "Thus, these is an urgent need to initiate development and evaluation of vaccines against these SARS-CoV-2 variants.

Only two vaccines, one developed by Pfizer (PFE  )-BioNTech (BNTX  ) and the other made by Moderna (MRNA  ), are approved for emergency use from the regulator in December. Since then, the Pfizer-BioNTech shot has demonstrated lower efficiency against the South African strain. Additionally, Moderna has announced plans to develop a booster shot to complement its vaccine against current and future strains.

Both vaccines are developed using messenger RNA, or mRNA, technology, which can be modified more quickly than other vaccine technologies and is able to be produced at mass rapidly.

More Vaccines

Britain's GlaxoSmithKline (GSK  ) and France's Sanofi (SNY  ) announced on Monday that the pair have begun a new clinical trials of their coronavirus vaccine candidate, with the drug expected to reach it final rounds of testing in the second quarter.

If the results are positive, the drugmakers plan to submit for emergency use approval by the fourth quarter. This new round of clinical trials comes after the pair's initial vaccine had demonstrated insufficient immune system responses in older, and more vulnerable to severe infection, participants.

The drugmaker's protein-based vaccine requires two doses administered approximately 21 days apart.