Patients with persistent symptoms of depression and cognitive impairment after a mild to moderate COVID-19 infection had elevated levels of a protein indicating inflammation of the brain, finds a Canadian case-control study published yesterday in JAMA Psychiatry.

The team led by researchers from the Centre for Addiction and Mental Health in Toronto used positron emission tomography (PET) to compare levels of translocator protein, a marker for gliosis (inflammation of the brain), in 20 participants with persistent symptoms of depression and cognitive impairment with those of 20 healthy controls.

The study was conducted from April 1, 2021, to June 30, 2022. Average participant age was 32.9 years, and roughly 60% were women.

Greatest difference in 2 brain regions

Translocator protein volume in the brain regions of interest was higher in participants with depressive and cognitive symptoms than in controls (mean difference, 1.51; 1.51 divided by 9.20, 17%).

The difference was most pronounced in two regions of the brain: the ventral striatum (mean difference, 1.97; 1.97 divided by 8.87, 22%) and dorsal putamen (mean difference, 1.70; 1.70 divided by 8.37, 20%).

"Gliosis may be consequent to inflammation, injury, or both, particularly in the ventral striatum and dorsal putamen, which may explain some persistent depressive and cognitive symptoms, including slowed motor speed, low motivation or energy, and anhedonia [reduced ability to experience pleasure]," the authors wrote.

In a related commentary, Alexander Gerhard, MD, of the University of Manchester in England, said the study was limited by PET's signal, which is not restricted to microglial cells.

"To target neuroinflammatory changes therapeutically, we will need a much more detailed understanding of microglial activation at different time points of neurological disorders," Gerhard wrote. "Not surprisingly, relatively simplistic attempts to suppress microglial activation have so far not resulted in clinical meaningful results."

Cats can become infected with COVID-19 through contact with other infected animals or contaminated pens and should be considered part of the household dynamics of the virus, according to a new study in Microbiology Spectrum.

"SARS-CoV-2 transmission between cats is efficient and can be sustained," said study author Wim van der Poel DVM, PhD, of Wageningen University and Research, in the Netherlands, in a press release. "Infections of cats via exposure to a SARS-CoV-2-contaminated environment cannot be discounted if cats are exposed shortly after contamination." 

The experiment involved 16 cats placed in different exposure groups. They were swabbed multiple times over the course of 3 weeks after exposure to either an infected cat or to a pen in which an infected cat was housed. Environmental samples were also taken.

Of the eight cats exposed to the contaminated pens, only one got infected, but three of four animals exposed to another infected animal became infected. The cats displayed mild symptoms, including nasal discharge.

"We found that the infectiousness of contaminated surfaces would decay within 8.8 (95% CI [confidence interval] = 1.5 to 31.2) hours, making transmission via contaminated surfaces alone inefficient," the authors wrote.

What about spread to people?

"We did not expose humans to the infectious cats. Our animal handlers were always fully protected," van der Poel said in the release. "We must assume that cat owners can be infected by SARS-CoV-2 infected cats since these cats excrete infectious virus." In fact, Thai scientists reported such an occurrence in June 2022.

"We should see our cat as part of the family regarding virus transmission," van der Poel added.

Pfizer yesterday announced that the US Food and Drug Administration (FDA) has approved its respiratory syncytial virus (RSV) vaccine—called Abrysvo—for use in adults ages 60 and older. In a close vote at the end of February, the FDA's vaccine advisory group recommended approval, with some members asking for more data.

The FDA's approval of Pfizer's vaccine gives the nation two RSV vaccines for use in older adults. On May 3, the FDA approved GlaxoSmithKline's RSV vaccine for the same age-group.

Pfizer's vaccine is an unadjuvanted bivalent recombinant subunit vaccine that contains antigens against two RSV subgroups, A and B.

The company said the FDA based its decision on data from a phase 3 study published in April in the New England Journal of Medicine. The study is ongoing, with efficacy data being collected in the second RSV season. Pfizer added that the Centers for Disease Control and Prevention (CDC) vaccine advisory group is slated to meet on Jun 21 to discuss a recommendation for use in older people.

Co-administration with flu vaccine

In other developments regarding the vaccine, the company said it will publish a phase 3 study in a peer-reviewed medical journal this month outlining the safety and immunogenicity of co-administering Abrysvo with flu vaccine. It added that it will launch studies to evaluate the vaccine in more groups including healthy children ages 2 to 5 years old, kids ages 5 to 18 who have underlying medical conditions, and younger adults who are at higher risk.

On May 18 the FDA's vaccine advisory group recommended Pfizer's RSV vaccine for use in pregnant women to protect newborns.