After two top vaccine directors at the Food and Drug Administration quit last year due to the debate over COVID-19 boosters, the agency has brought on a new vaccine director to helm the upcoming fall vaccination campaign.

David Kaslow, who was previously VP of vaccines and infectious diseases at Merck Research Laboratories, will step into the director role at the CBER’s Office of Vaccines Research and Review.

The move comes as the Biden administration is preparing a fall COVID-19 booster push. The FDA emergency recently authorized both the Pfizer and Moderna bivalent vaccines. Also referred to as “updated boosters,” the bivalent vaccines contain the original strain of the COVID-19 virus as well as an Omicron-targeted strain.

The Centers for Disease Control and Prevention followed up on the authorization, recommending a shot for anyone over the age of 12 who received a full vaccination more than two months ago.

“As we head into fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against currently circulating variants,” FDA commissioner Robert Califf said in a statement.

The approach is similar to last year’s ‘boosters-for-all’ strategy, which pushed to get boosters into arms despite hesitation among some FDA scientists. It’s also a sign that updated boosters-for-all may become annual as the pandemic wears on and the FDA experiences some friction between policy and science over the issue.

In fall 2021, Marion Gruber and Philip Krause both left the agency after voicing their opposition to the booster approach. In September 2021, an FDA advisory panel decided not to recommend an extra dose to the general population, suggesting it be limited to people aged 65 and older — or those who are immunocompromised. Data that the panel reviewed at the time showed fully vaccinated people were still highly protected against severe illness or hospitalization.

That decision clashed with President Biden’s plan to begin rolling out boosters-for-all later in the month.

In an article published in The Lancet, Gruber and Krause stated that the federal government wasn’t taking the proper evidence and science into account. 

“Although the idea of further reducing the number of COVID-19 cases by enhancing immunity in vaccinated people is appealing, any decision to do so should be evidence-based and consider the benefits and risks for individuals and society,” they wrote.

In an article published in The Washington Post, Gruber and Krause also argued that the push for boosters could prolong the pandemic and affect perception of the shots.

“The campaign includes exaggerated accounts of the waning efficacy of the vaccines, giving the public — including the vaccine-hesitant — reason to think that the shots are less effective than originally advertised,” they wrote.

Many of these questions still remain a year later as the new bivalent boosters are being rolled out. Meanwhile, Kaslow will be taking over the Office of Vaccines Research and Review next month, replacing Peter Marks, who served as its acting director since Gruber left last year.

Finding a way to balance the likely annual rollout of updated COVID-19 boosters — while still having the FDA churn out studies and data that prove their efficacy over time — will be one major task on Kraslow’s to-do list.

Considerable questions about the science surrounding continued booster campaigns still remain, such as weighing how much more effective updated boosters would be compared to original vaccination.

There’s also the concern about whether it’s worth it, financially. 

The Biden administration spent $3.2 billion to secure 105 million doses of Pfizer’s updated vaccine despite the fact that it’s still unclear whether the boosters will be beneficial among all age groups and populations in the U.S. That’s particularly notable given Congress’ halt on approving new COVID-19 funds.

Kaslow will also likely face another overarching topic that has impacted the boosters-for-all discussion: vaccine equity globally. Both Gruber and Krause argued in their Lancet article that primarily focusing on marginalized populations in the U.S. and low-income nations globally for the first round of vaccination would be the most effective way to curb the pandemic’s effects worldwide.

Kaslow, who spent more than a decade at global health nonprofit PATH — joining in 2012 as director of the organization’s Malaria Vaccine Initiative — brings some experience in this arena.

While there, Kraslow led various initiatives to boost development of vaccines for women and children around the world. Additionally, he worked on developing vaccines for other viruses, including rotavirus, typhoid, polio and enterotoxigenic E. coli. He also previously founded the Malaria Vaccine Development unit at the National Institutes of Health.