The expected green light for a second coronavirus booster shot poses a challenge to the Biden administration, which will need to work overtime to convince a public that has largely decided to move on from the COVID-19 pandemic.

Both Pfizer and Moderna have filed for emergency use authorization with the Food and Drug Administration for a fourth dose of their respective vaccines, citing evidence that protection from the third shot has decreased enough to warrant a fourth dose.

Yet the nation’s vaccination and booster rates have dropped to record lows, just as experts and officials are bracing for the possibility of another wave of infections from the BA.2 subvariant of omicron.

The BA.2 version of omicron is much more transmissible than the original variant. Combined with relaxed precautions like indoor masking and waning immunity among those who have not received a vaccine booster, cases have risen sharply in Europe in the past few weeks, and the U.S. could follow shortly. 

The omicron subvariant is responsible for about 35 percent of all cases in the country. In some regions though, like the northeast, it is responsible for the majority of infections.

Federal health officials are reportedly poised to authorize a fourth dose of coronavirus vaccine for adults age 50 and older as soon as this week. A fourth shot is already authorized for the immunocompromised.

But the issues that plagued the administration during the first booster campaign loom large, and officials are likely eager to avoid the same pitfalls. 

Chaotic and at times disparate messages from administration health officials culminated in a complicated set of recommendations about who should be getting booster shots, and why, which experts said helped depress enthusiasm. 

“I think that some of the low uptake of boosters, especially amongst people who would benefit, the high risk population, is because that message has been diluted,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.

But the underlying disagreement about the goal of booster shots has not changed. While there’s widespread agreement that older Americans are much more at risk for severe outcomes, it’s still not clear if younger people will benefit from an additional dose. 

Much of the debate has centered on whether the goal is to prevent people from being hospitalized with COVID-19 or whether the goal is to prevent them from getting sick at all, even if it is milder. 

Anthony Fauci, White House chief medical advisor and the nation’s top infectious disease doctor, said regulators are trying to determine how low protection against hospitalization needs to drop before a booster is warranted.

“So the real open question that we don’t know definitively the answer to, is how long is the durability of protection against severe disease going to last even when the protection against infection diminishes substantially,” Fauci said during a Washington Post event last week. 

“For example, we know that when you get down to a rather low level 30, 40 or so percent of protection against infection, you still have, when you look at hospitalization, a high degree [of protection],” Fauci said.

President Biden last summer promised widespread boosters for all Americans by the end of September, well before the FDA and the Centers for Disease Control and Prevention (CDC) had examined the evidence. 

While officials were careful to say the booster program was contingent on the FDA and CDC giving the green light, scientists inside and outside the government argued there wasn’t enough evidence showing protection against severe illness and hospitalization dropped to levels that warranted a booster.

The CDC initially decided against recommending broad authorization, and instead recommended a booster shot for people over the age of 65, as well as anyone who was at “high risk” of exposure to the virus in the workplace. 

The agency eventually decided to make everyone eligible, but by then much of the damage had been done. Vaccinated Americans have largely shown they are not interested in getting a booster.

According to current CDC data, less than 45 percent of all adults have received a booster shot, but the number rises to about 67 percent of adults age 65 and older. 

Adalja said it makes sense to be proactive and have a plan to get additional booster shots to the older group. But he said the decisions should be left to the scientists, and the health agencies should make decisions independent of the White House. 

“Keep the politicians out of it,” Adalja said. “The miscommunications occurred because they made boosters a political issue, not a scientific issue.”

But even if there is a targeted recommendation, a stalled funding request in Congress further complicates matters. The U.S government does not have enough doses on hand to vaccinate everyone who would be eligible for another booster.

The White House says it needs tens of billions of dollars in COVID response funding, which is tied up due to political disagreements. Administration officials say they don’t have enough doses on hand to cover anyone other than the immunocompromised and people aged 65 and older.

But an independent analysis from the Kaiser Family Foundation found the government only has enough vaccine supplies to cover 70 percent of the 65 and older group.