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PGY-2 Pharmacotherapy Resident at the Medical University of South Carolina.

At MAD-ID 2025, Dakota Rorie, PharmD, highlights cost and access barriers to uptake of preferred CDI therapy.

Fidaxomicin Use Remains Flat Despite Guideline Change for C difficile Treatment

Along with a 1 reported case in Massachusetts, the

New Hampshire Department of Health and Human Services (DHHS) has confirmed a person infected with eastern equine encephalitis (EEE) has died. The public health agency said the person was hospitalized due to severe central nervous system disease. The last reported human EEEV infection in New Hampshire was in 2014, when DHHS identified 3 human infections, including 2 fatalities. In the same statement, DHHS mentions there has been 1 confirmed case in Vermont this summer.

On August 16, the Massachusetts Department of Public Health (MDPH) released a statement discussing the confirmation of the first human case of EEE in the state this year. The confirmed case was discovered in an 80 year old man who was exposed to the vector borne disease in Worcester County. As a result, the risk level in the local communities of Douglas, Oxford, Sutton, and Webster has been raised to critical, and in Dudley, Northbridge, and Uxbridge the risk is increased to high.

Additionally, the neighboring communities of Auburn, Charlton, Grafton, Leicester, Mendon, Millbury, Millville, Southbridge, and Upton are now considered at moderate risk according to MDPH.

“This is the first time we have seen a person infected with EEE in Massachusetts since 2020,” Public Health Commissioner Robbie Goldstein, MD, PhD, said in a statement. “EEE is a rare but serious disease and a public health concern. We want to remind residents of the need to protect themselves from mosquito bites, especially in areas of the state where we are seeing EEE activity.

Though very rare, EEE is serious and a potentially fatal disease that can affect people of all ages. EEE is generally spread to humans through the bite of an infected mosquito. There were 12 human cases of EEE in Massachusetts in 2019 with 6 deaths, and 5 human cases with 1 death in 2020. There were no human cases of EEE in Massachusetts in 2021, 2022, or 2023.

EEE has a fatality rate of 33% to 70%, with most deaths occurring 2–10 days after the onset of symptoms.

In addition to a high mortality rate, long-term physical and mental complications, including permanent neurological deficits have been identified in many people who survive EEE.

Plymouth is approximately 40 miles south of Boston along the coast, and Worcester County is in the middle of the state, so the 2 areas are not in close proximity, but due to the elevated risk locally, the town of Plymouth decided to take action in response to outdoor parks. As of last Friday, all town public parks and fields are close daily from dusk until dawn.

“As Mass DPH has now elevated Plymouth’s EEE risk status to high, it is important to take extra precautions when outdoors and follow state and local health guidelines to avoid unnecessary risk to exposure to EEE. The health and safety of our community, residents, and visitors remain our priority,” Plymouth’s Commissioner of Health and Human Services, Michelle Bratti, said in a statement.

According to the Centers for Disease Control and Prevention (CDC) most people who are infected with the virus do not develop symptoms; however, for those that do, the date from the bite to the onset of the illness is 4 to 10 days. EEE can also result in fever or neurologic disease. The type of illness will depend on the age of the person and other factors. Those who are infected can develop meningitis.

There are no FDA-approved treatments for EEE and for patients who develop severe cases, they can be hospitalized to receive supportive treatment.

Over the weekend, MDPH detailed plans of spraying for mosquitos including aerially in areas of Plymouth County, and truck-mounted spraying in parts of Worcester County. As of Saturday, 10 communities in Massachusetts were raised to high or critical risk for EEE virus.

“The risk from EEE is high in parts of Plymouth County and critical in parts of Worcester County,” State Epidemiologist Catherine M. Brown, DVM, said in a statement. “In addition to recommending that people use mosquito repellent with an EPA-registered active ingredient and clothing to reduce exposed skin, we also recommend that evening outdoor events be rescheduled to avoid the hours between dusk and dawn. The mosquitoes most likely to spread EEE are most active during the dusk to dawn hours.”

There are preventative strategies to avoid EEE, and the MDPH has listed such measures 

For those who live in Massachusetts and want more information on EEE, it can be found 

 or by calling the DPH Division of Epidemiology at 617-983-6800.

1.NH DHHS Identifies Person Infected with Eastern Equine Encephalitis Virus in New Hampshire.The New Hampshire Department of Health and Human Services. August 27, 2024. Accessed August 28, 2024.
https://www.dhhs.nh.gov/news-and-media/nh-dhhs-identifies-person-infected-eastern-equine-encephalitis-virus-new-hampshire
2. State health officials announce season’s first human case of Eastern Equine Encephalitis in Massachusetts. MDPH. August 16, 2024. Accessed August 27, 2024.
https://www.mass.gov/news/state-health-officials-announce-seasons-first-human-case-of-eastern-equine-encephalitis-in-massachusetts
3.Plymouth to Close all Public Parks and Fields from Dusk to Dawn. Town of Plymouth. August 23, 2024. Accessed August 27, 2024. PDF.
4. Eastern Equine Encephalitis: Symptoms, Diagnosis, and Treatment. CDC. May 15, 2024. Accessed August 27, 2024.
https://www.cdc.gov/eastern-equine-encephalitis/symptoms-diagnosis-treatment/index.html
5. State officials announce plans to spray for mosquitoes in sections of Worcester and Plymouth counties due to EEE. MDPH. August 24, 2024. Accessed August 27, 2024. 
https://www.mass.gov/news/state-officials-announce-plans-to-spray-for-mosquitoes-in-sections-of-worcester-and-plymouth-counties-due-to-eee



The town of Plymouth decided to prohibit people from using the parks from dusk to dawn due to concerns over eastern equine encephalitis after a man contracted the rare disease in the state.

Concerns Over Mosquito-Borne Illness Causes Massachusetts Town to Create Curfew for Parks, Spraying in Counties

Paul Feuerstadt, MD, discuses the treatment’s overall safety and efficacy profile as well as looking at smaller subsets of patients with comorbidities.

Reviewing Real-World Safety and Efficacy Data on C difficile Therapy Rebyota

Fecal microbiota, live-jslm (Rebyota [RBL]), which is indicated for treatment of recurrent 

has been FDA approved for over 2 years now, and with it comes real-world efficacy and safety data. 

Paul Feuerstadt, MD, FACG, AGAF, associate clinical professor of Medicine at Yale School of Medicine, has been involved with studies around this therapy for several years, and believes the product is very safe and effective.

He provides details about an abstract presented at the Digestive Disease Week conference that looked at 5 prospective trials, including 2 randomized control trials and multiple open label studies. “It was an integrated safety analysis of those trials, including 1,192 individuals who received at least of 1 dose of RBL, 769 who received 1 dose of RBL, and 83 who received placebo. And then in effect, showed that there was consistency of adverse events between the placebo and those who received RBL, and that consistency shows that RBL doesn't leave patients at greater risk for adverse events and serious adverse events,” Feuerstadt said. “Serious adverse events were 11.2% for a single dose of RBL, and 7.2% for a single dose of placebo.”

Additionally some of the trial participants had comorbidities such as inflammatory bowel disease (IBD) and mild to moderate immunocompromised states. Specifically, Feuerstadt describes the results of an open label study which included 71 participants who had IBD.

“The efficacy was 78.9% at 8 weeks within that population; with an 80% efficacy in those with Crohn's disease and a 76.2% efficacy in those with ulcerative colitis. So, it was very consistent with the phase 3 data as well as the overall open label group,” he said.

For those with an immunocompromised state, Feuerstadt says this population performed well with efficacy, which was 75.7% at 8 weeks, and 88.7% remained responsive. 

“Paramount to all this is safety, and the safety profiles were consistent, regardless of immune compromised state or inflammatory bowel disease,” Feuerstadt said. “Now, when we contextualize this with guidelines—the American Gastroenterological Association in February of 2024—said that we should be considering microbiota restoration in FDA approved products in the immune competent, but for the immune compromised, they said there was insufficient data." 

However, he points to new data in a phase 3 open label study of 140 individuals who were mild to moderately immune compromised, which he says, proves Rebyota is a safe therapy for this population. 



Paul Feuerstadt, MD, discuses the treatment’s overall safety and efficacy profile and provides insights on data around smaller subsets of patients with comorbidities.

In an article published this week in the 

, FDA Commissioner Marty Makary, MD, MPH, and Vinay Prasad, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research (CBER), laid out their plan that will change the bar for how COVID-19 vaccines will be approved going forward.

They are seeing this through 3 groups: adults 65 years of age and older, those between the ages of 6 months and 64 years, and high-risk groups. They are taking a differing approach for each of them.

“On the basis of immunogenicity — proof that a vaccine can generate antibody titers in people — the FDA anticipates that it will be able to make favorable benefit–risk findings for adults over the age of 65 years and for all persons above the age of 6 months with one or more risk factors that put them at high risk for severe COVID-19 outcomes, as described by the CDC,” the authors wrote. “For all healthy persons — those with no risk factors for severe COVID-19 — between the ages of 6 months and 64 years, the FDA anticipates the need for randomized, controlled trial data evaluating clinical outcomes before Biologics License Applications can be granted. Insofar as possible, when approving a COVID-19 vaccine for high-risk groups, the FDA will encourage manufacturers to conduct randomized, controlled trials in the population of healthy adults as part of their postmarketing commitment.”

Makary and Prasad say the public has developed a mistrust in vaccines overall and they point to the reduced uptake of COVID-19 boosters in recent years as evidence as well as families refusing to get the MMR vaccine, which has led to a serious measles outbreak that has over 1,000 confirmed cases and led to 3 deaths in 2025.

“Less than 25% of Americans received boosters each year, ranging from less than 10% of children younger than 12 years of age in the 2024–2025 season to 50% of adults over 75 years old,” they wrote.

The authors point out that people in the 50–64-year-old age range would be the ideal group to study for future FDA-recommended placebo-controlled trials for COVID-19 vaccines.



For all healthy persons — those with no risk factors for severe COVID-19 — between the ages of 6 months and 64 years, the FDA anticipates the need for randomized, controlled trial data evaluating clinical outcomes before Biologics License Applications can be granted.—Marty Makary, MD, MPH, and Vinay Prasad, MD, MPH



They say their policy points out the need for evidence to prove if another booster will help a person who has had both COVID-19 and been vaccinated multiple times.

“The FDA’s new COVID-19 philosophy represents a balance of regulatory flexibility and a commitment to gold-standard science. The FDA will approve vaccines for high-risk persons and, at the same time, demand robust, gold-standard data on persons at low risk. These clinical trials will inform future directions for the FDA, but more important, they will provide information that is desperately craved by health care providers and the American people,” they write.

1.Prasad V, Makary MA. An Evidence-Based Approach to Covid-19 Vaccination. 

. Published online May 20, 2025. doi:10.1056/NEJMsb2506929

FDA leadership says they expect more testing for COVID-19 vaccines and that they generate antibody titers in people in order for vaccines to be considered for approval. 

FDA Shifts COVID-19 Vaccine Policy, Requires Further Testing

Pediatrician Sharon Nachman, MD, discusses the potential effects of the new policy including how issues like vaccine access, incidence rates and participation in placebo-controlled trials may change. 

How Will the New FDA Vaccine Policy Affect the Pediatric Population?

This is the second piece in a series on the new FDA COVID-19 vaccine policy being proposed.

On Tuesday, in an article published in the 

FDA Commissioner Marty Makary, MD, MPH, and Vinay Prasad, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research (CBER), laid out their plan to change policy as it relates to COVID-19 vaccines.

Whereas, previously everyone who was 6 months and older were recommended to get vaccines, now the FDA is no longer recommending annual COVID vaccinations for healthy people younger than 65. For those who are 65 and older they are still recommended to get their annual vaccinations as well as those 6 months and older who have underlying health conditions such as diabetes, cancer, asthma, etc.

With these new rules this will likely change how insurers cover these vaccines, leaving the cost to families. And this will likely leave clinicians without easy access to COVID-19 vaccines for those families who would like to still vaccinate their children.

“I think that pediatricians will not have it in their office, so that means families will have to figure out how to get it,” Sharon Nachman, MD, chief of pediatric infectious diseases at Stony Brook Children's Hospital, said. “The children are in school, the families are working, and most of the pharmacies did not want to vaccinate children under 5 and sometimes even under 8. So that means for the school aged children that we would like to vaccinate, there's not going to be a whole lot of access for them, even if they're willing to pay for the vaccine.”

Nachman acknowledges children do not suffer the same severe disease and mortality that adults do with COVID-19; however, she does caution against changing variants and Long COVID.

“Most children handle COVID quite well, but as we see new variants, we don't know what damage those new variants will do— I am concerned," Nachman said. “And furthermore, when we look at the data on who got Long COVID, not only just among children, but adults, there is fascinating information now from multiple studies that people that got vaccinated had a much lower risk of Long COVID.”

Another prospective issue is placebo-controlled trials for COVID-19 vaccines. Nachman believes this will be problematic for future studies and a hard sell for families to participate in.

“I think there's a lot of concern from infectious disease doctors about the idea that you have to test every new variant of COVID with the vaccine against a placebo,” Nachman said. “Certainly, as a parent, do I really want to give my kids a placebo vaccine when I know that we're seeing another rise of COVID in the children in schools and at home? So, I think that families will have a hard time signing on to a clinical trial when a licensed vaccine is available.”




Pediatrician Sharon Nachman, MD, discusses the potential effects of the new policy including how things like vaccine access, incidence rates, and participation in placebo-controlled trials may change. 

How Will the New FDA COVID-19 Vaccine Policy Affect the Pediatric Population?

It has been a busy week for FDA-related COVID-19 vaccine news. On Tuesday, in an article published in the 

, FDA Commissioner Marty Makary, MD, MPH, and Vinay Prasad, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research (CBER), laid out their plan that will change the bar for how COVID-19 vaccines will be approved going forward as well as who will be eligible to receive the seasonal vaccines.

With this major COVID-19 vaccine FDA policy changes as a backdrop, the FDA Vaccines and Related Biological Products Advisory Committee (VRBPAC) met yesterday to decide what COVID-19 strains should be included in the vaccines for this coming seasonal respiratory season.

The committee unanimously voted to recommend a monovalent JN1-lineage vaccine composition. Following the vote, the committee discussed considerations for the selection of JN1 and/or a specific JN1-lineage strain for COVID-19 vaccines (2025-2026 Formula).

During this meeting, the advisory committee was informed of the manufacturing timelines, they reviewed the available data on the circulation of SARS-CoV-2 virus variants, current vaccine effectiveness, human immunogenicity data of current vaccines against recently circulating virus variants, the antigenic characterization of circulating virus variants, animal immunogenicity data on new candidate vaccines expressing or containing updated spike components, and human immunogenicity data on the COVID-19 vaccines (2024-2025 formula).

Based on the totality of the evidence, FDA has advised the manufacturers of the approved COVID-19 vaccines that to more closely match currently circulating SARS-CoV-2 viruses, the COVID-19 vaccines for use in the United States beginning in fall 2025 should be monovalent JN1-lineage-based COVID-19 vaccines (2025-2026 Formula), preferentially using the LP81 strain.

Although it appears the formulation for the 2025-2026 vaccines will not need to go through clinical trials, the policy going forward is to require placebo-controlled trials for COVID-19 vaccines in order for them to seek FDA approval. This could take months and therefore the potential of being unprepared going into a respiratory virus season is very real.

“A new vaccine will not roll out in a timely fashion for it to be useful in that season,” Sharon Nachman, MD, chief of pediatric infectious diseases at Stony Brook Children's Hospital, said. “Just playing by the numbers, you will need several 100 people to be enrolled on a vaccine study and wait to see if they have any side effects or if there's any problems with the vaccine or placebo, which means it has to go through a season.”

In terms of who is eligible for COVID-19 vaccines, that policy had changed drastically. Whereas, previously everyone who was 6 months and older were recommended to get vaccines, now the FDA is no longer recommending annual COVID vaccinations for healthy people younger than 65. For those who are 65 and older they are still recommended to get their annual vaccinations as well as those 6 months and older who have underlying health conditions such as diabetes, cancer, asthma, etc.

For those who are not in those patient populations, it leaves clinicians, families, and individuals with questions about access and eligibility.

“Unfortunately, that basically does eliminate access of vaccination to the majority of the pediatric population,” Tina Tan, MD, FIDSA, FPIDS, FAAP, Infectious Diseases Society of America (IDSA) president, said in an interview with 

. And COVID 19 is a disease that occurs in children. Even though there is all this misinformation out there that COVID 19 doesn't cause infection in children, but it does…some kids can actually get quite sick with it, and they can develop Long COVID symptoms.”

Nachman also sees the potential complication of Long COVID. “When we look at the data on who got Long COVID, not only just among children, but adults, there is fascinating information now from multiple studies that people that got vaccinated had a much lower risk of Long COVID,” Nachman said.

This new policy may lead to delays in vaccine rollouts in the future.

“That's going to be a major factor in delaying whether or not individuals are going to be able to receive the vaccine, and that is not how this should be done, because we know these vaccines work,” Tan said. “The vaccines are being reformulated every year to take into account the circulating sub stereotypes. And you know, there's no need for a clinical trial to prove that these vaccines work; we know the vaccines work. We know the vaccines are safe…you're really going to delay availability.”

Clinicians point out that limiting access will be a major issue for some who wish to get vaccinated but will likely now how to pay for it. 

“Limiting broad access to updated vaccines while COVID-19 continues to circulate is a dangerous gamble. We must not weaken our defenses against a virus that still poses a serious public health threat,” NFID Medical Director Robert H. Hopkins Jr, MD, said in a statement to 




Reference
1. COVID-19 Vaccines (2025-2026 Formula) for Use in the United States Beginning in Fall 2025. FDA. May 22, 2025. Accessed May 23, 2025.
https://www.fda.gov/vaccines-blood-biologics/industry-biologics/covid-19-vaccines-2025-2026-formula-use-united-states-beginning-fall-2025

The FDA committee advisors are recommending the monovalent JN1-lineage-based COVID-19 vaccines  preferentially using the LP81 strain. 

FDA VRBPAC Makes Recommendations For 2025-2026 Formula for COVID-19 Vaccines

Alexander Laurenson presents T cell-focused tool at 2025 Vaccinology Conference using data from 18 countries and 748 HLA alleles to address immune diversity in Africa.

Computational Model Maps Over 67,000 Malaria Epitopes to Improve Vaccine Targeting

A new computational pipeline developed at the University of Maryland School of Medicine may help improve malaria vaccine development by addressing two major challenges: the genetic diversity of 

 and variability in human immune genes across African populations. The model was presented at the 2025 Annual Conference on Vaccinology Research.

The approach uses mixed-integer linear programming to identify T cell epitopes that are conserved, immunogenic, and broadly recognizable across a range of human leukocyte antigen (HLA) alleles. The tool evaluates parasite sequences from 18 African countries and 748 unique HLA alleles from 24 African nations. It then selects combinations of epitopes that maximize population-level immune coverage while reducing the likelihood of immune escape.

From a set of 42 candidate proteins, the model identified more than 65,000 class I and nearly 2,000 class II epitopes. The most promising liver-stage antigens included HSP70-2, ROM1, and LISP1. Blood-stage antigens included RON2, PfRh5, and EBA-175. Among the most optimized results, five MHC class I epitopes independently covered 100 percent of HLA-A, -B, and -C alleles. MHC class II coverage ranged from 98.5 to 100 percent when epitopes from multiple parasite stages were combined.

Alexander Laurenson, a second-year MD/PhD student and lead investigator, said the pipeline aims to help researchers narrow their focus before entering more costly stages of vaccine testing. “What I think we’re experiencing right now in a lot of the malaria vaccine development pipeline is a bottleneck in determining what exactly to target,” Laurenson said. “Plasmodium falciparum is a eukaryote, so it has an enormous genome. That means there are a lot of components that allow for redundancy in how the pathogen invades, causes disease, and survives in the host.”

Laurenson noted that by using this tool early in the vaccine development pipeline, researchers can reduce time spent on expensive laboratory assays.“We’re hoping this tool is integrated effectively so we can at least generate a shortlist of potential antigens or epitopes to target before moving on to that expensive and tedious step,” he said.

The tool also focuses on enhancing HLA coverage, a factor tied to the ability to activate T cells, which support longer-lasting and more durable immune responses.“When we talk about HLA coverage, we’re covering a much more complicated concept related to the activation of T cells,” Laurenson said. “This is something that’s often less emphasized in vaccinology, where the focus is usually on generating a robust antibody response—which is, rightfully, considered highly protective.”

“But in this case, we’re focusing on what I sometimes call the ‘middle child’ of the immune response—T cells—that help do a few important things. CD8 T cells go after infected host cells to kill them and squash the infection when it’s hiding inside our cells. CD4 T cells, when activated, fully activate B cells, which is key for those B cells to become memory B cells and produce long-lasting antibodies.”

By improving T cell engagement, the model may contribute to longer-lasting immunity and potentially reduce the frequency of booster doses needed in the field. Laurenson said the tool was designed to be scalable and adaptable to other vaccine targets. 

“We’re not just in the business of designing malaria vaccines—we’re also interested in designing tools that could be used for other understudied, neglected, or elusive pathogens,” he said. “We’re looking at applying this work to pathogens that have been difficult to target with vaccines due to high antigenic diversity, or where there’s variability in immune response between individuals.”

He noted that this includes diseases like influenza, COVID-19, and hepatitis B, where breakthrough infections remain common and vaccine coverage varies.“We really want to figure out how this overall strategy could be used not just for malaria, but for other emerging or elusive pathogens,” Laurenson said. Next steps include experimental validation of the model’s epitope predictions and integration into vaccine platforms that support durable immune responses.

Laurenson A, Laurens MB. A novel computational approach to 

 vaccine design to address human leukocyte antigen restriction and parasite diversity. Poster #1 presented at the 2025 Annual Conference on Vaccinology Research. May 5-7, 2025; Washington, DC.

Alexander Laurenson presents T-cell-focused tool at the 2025 Vaccinology Conference using data from 18 countries and 748 HLA alleles to address immune diversity in Africa.

Dakota Rorie, PharmD

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