Early safety data on RSV vaccines show rare Guillain-Barre cases

News brief

Late last week in Mrbidity and Mortality Weekly Report, researchers published the first clinical safety data on Arexvy and Abrysvo vaccines, the first approved respiratory syncytial virus (RSV) vaccines, and found real-world data mimics what was seen in trials, including a very small increased risk in Guillain-Barre syndrome (GBS).

GBS is an immune system disorder that occurs when the immune system attacks nerves. It is characterized by numbness and tingling in the body, including paralysis. GBS can follow bacterial or viral infections, and, rarely, following vaccination.

Arexvy and Abrysvo, made by GSK and Pfizer, respectively, were approved by the US Food and Drug Administration in May 2023 for use in adults 60 and older to prevent RSV infections.

28 cases of GBS reported

From August 4, 2023, to March 30, 2024, at least 10.6 million US adults aged 60 years and older received a recommended RSV vaccine. The study is based on reports made to both V-safe and the Vaccine Adverse Event Reporting System (VAERS) from May 3, 2023, through April 14, 2024.

"Among the 16,220 V-safe participants aged ≥60 years who reported receiving an RSV vaccine and completed one or more daily surveys, 39.0% reported at least one symptom after vaccination; 0.4% of participants reported receiving medical care," the authors said.

Over ninety percent of events in VAERS were classified as nonserious. However, VAERS included 28 reports of GBS that met case definition, including 11 (39.3%) after Arexvy vaccine (1.5 reports per 1 million doses administered), and 17 (60.3%) after Abrysvo (5.0 reports per 1 million doses administered).

CDC [Centers for Disease Control and Prevention] and FDA are conducting active safety evaluations to assess risks for GBS and other adverse events of special interest after RSV vaccination.

"CDC [Centers for Disease Control and Prevention] and FDA are conducting active safety evaluations to assess risks for GBS and other adverse events of special interest after RSV vaccination. Results of these studies will help guide future CDC RSV vaccine recommendations," the authors concluded.

Pasteurization neutralizes avian flu viruses in milk, researchers find

News brief

Mary Van Beusekom, MS

UK researchers report that industry-standard pasteurization inactivates influenza A viruses (IAVs) in milk, according to a study posted late last week on the preprint server medRxiv.

A team led by University of Edinburgh researchers tested whether pasteurization could neutralize the infectivity of human and avian IAVs, as well as an influenza D virus that naturally infects cattle and recombinant IAVs with contemporary avian or bovine H5N1 glycoproteins. To do so, they heated the milk to 63°C [145°F] for at least 30 minutes and 72°C [162°F] for 15 seconds.

"In late 2023 an H5N1 lineage of high pathogenicity avian influenza virus (HPAIV) began circulating in American dairy cattle," the authors noted in the study, which has not yet been peer-reviewed. "Concerningly, high titres of virus were detected in cows' milk, raising the concern that milk could be a route of human infection."

Raw milk could contain flu viruses, other pathogens

"At both 63°C and 72°C, the infectivity of all viruses was rapidly lost, dropping by orders of magnitude in seconds and falling below the limit of detection well in advance of the minimum times required for milk pasteurization," the team wrote.

We conclude that industry standard pasteurisation conditions should effectively inactivate H5N1 HPAIV in cows' milk, but that unpasteurised milk could carry infectious influenza viruses.

To test whether wild-type H5N1 AIV in particular is susceptible to pasteurization, the team added the virus to raw milk to ascertain its infectivity. After being subjected to heat, only genetic material—not infectious virus—was detected in the milk.

"We conclude that industry standard pasteurisation conditions should effectively inactivate H5N1 HPAIV in cows' milk, but that unpasteurised milk could carry infectious influenza viruses," the researchers concluded. "We therefore caution against the consumption of raw milk that could be contaminated with bovine IAV because of the risk of consuming infectious virus, in addition to its established risk for infection with other viral and bacterial pathogens."

Study: Sepsis quality metrics may unfairly penalize safety-net hospitals

News brief

Chris Dall, MA

A cohort study involving more than 2.5 million older patients with sepsis found that admission to safety-net hospitals was associated with higher in-hospital mortality than non–safety-net hospitals, researchers reported late last week in JAMA Network Open.

The authors of the study say the findings may be tied to the greater use of hospice at non–safety-net hospitals, which shifts attribution of death from the index hospitalization to hospice care.

The study, led by researchers at Boston University (BU) Medical School and Beth Israel Deaconess Medical Center, examined medical record of Medicare fee-for-service beneficiaries aged 66 years and older who were admitted with sepsis to an intensive care unit from January 2011 to December 2019. Co-primary outcomes included in-hospital mortality and 30-day mortality.

No difference in 30-day mortality

More than 2.5 million patients with sepsis (mean age, 78.8 years; 51.9% female; 83.8% White) were admitted to 666 safety-net hospitals and 1,924 non–safety-net hospitals during the study period. Admission to safety-net hospitals was associated with higher in-hospital mortality (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.06 to 1.13) but not 30-day mortality (OR, 1.01; 95% CI, 0.99 to 1.04), which the authors say is a less biased measure of short-term mortality.

Admission to safety-net hospitals was also associated with lower do-not-resuscitate rates (OR, 0.86; 95% CI, 0.81 to 0.91), palliative care delivery rates (OR, 0.66; 95% CI, 0.60 to 0.73), and hospice discharge (OR, 0.82; 95% CI, 0.78 to 0.87) but not with discharge to postacute facilities (OR, 0.98; 95% CI, 0.95 to 1.01).

The authors say the findings are significant because while the differences between safety-net and non–safety-net hospitals were small, they were enough to affect hospital rankings. New York is among the states that uses in-hospital mortality to evaluate how hospitals perform on sepsis quality measures.

"Current or future state and federal quality measures that use in-hospital mortality as a quality metric may unfairly penalize safety-net hospitals," corresponding author Anica Law, MD, assistant professor of medicine at BU School of Medicine, said in a press release.

Law and her colleagues say their findings can be used to guide selection of better outcome measures for publicly reported quality benchmarks.