(The Hill) – The Biden administration will be giving elderly Americans a second COVID-19 booster shot, multiple people familiar with the plan told The New York Times.

Those above the age of 50 will be able to get a second booster of either the Pfizer-BioNTech or Moderna vaccines.

However, multiple issues complicate the plan as the administration has to calculate when the next COVID-19 wave could hit the U.S., sources told the Times. The administration will want to get the second booster to the elderly before another wave hits, but not too far before that protection could wane.

Other complications include how to explain the plan to the public and how long the second booster’s protection will remain strong, the Times noted.

White House adviser Anthony Fauci said last week that COVID-19 cases could begin increasing in the coming weeks. 

“I would not be surprised if in the next few weeks we see somewhat of either a flattening of our diminution or maybe even an increase,” Fauci said on the ABC News podcast “Start Here.”

However, it is unclear how dangerous this wave could be compared to past increases as the BA.2 variant begins to become dominant in the U.S. 

The Hill has reached out to the White House for comment.