In a meeting that took place Wednesday, the Food and Drug Administration said that regulators need to determine if additional or different COVID-19 vaccines will be needed by June of this year.

As variants continue to emerge, New England Journal of Medicine editor-in-chief Dr. Eric Rubin called the meeting “a good opportunity to show how complex the decision-making is going to be going forward," as reported by CNN.

The FDA’s head of vaccine safety Dr. Peter Marks said that in order for shots to be available this fall, a verdict regarding future doses needs to be reached this June. According to CNBC, vaccine manufacturers including Moderna and Pfizer are currently working to create variant-specific doses.

"Many variants are coming, and Omicron was the first one that was able to evade, in a skillful way, the immune protection that we're giving," Pfizer CEO Albert Bourla told CBS in March, claiming that a fourth dose is "necessary."

In a study published in March by the Centers for Disease Control and Prevention, the health agency advised recipients of Johnson & Johnson’s single-dose vaccine to get a booster with one of Pfizer or Moderna's mRNA vaccines. The guidance was made in response to the rare but potentially life-threatening adverse effects of J&J's vaccine, such as blood clots.