The Pfizer-BioNTech BNT162b2 messenger RNA COVID-19 vaccine was found to be highly effective in preventing asymptomatic, symptomatic, and severe SARS-CoV-2 infection.^1-4 Israel was among the first countries to achieve significant nationwide vaccination coverage, leading to rapid containment of SARS-CoV-2 transmission in the community.^5,6 However, resurgence of COVID-19 cases predominated by the Delta variant was observed in June 2021^6,7 and raised concerns about waning immunity of the BNT162b2 vaccine. Declining protection of BNT162b2 against SARS-CoV-2 infection and hospitalization 4 months or more after full vaccination was demonstrated among individuals aged 60 years or older, in which those who completed a 2-dose series in March 2021 had a lower risk of SARS-CoV-2 infection compared with those vaccinated in January 2021.⁷ Similarly, analysis of US data of adults without immunocompromising conditions showed a significant decline in the effectiveness of the BNT162b2 vaccine against COVID-19 hospitalizations, from 91% to 72% more than 120 days after completion of vaccination.⁸ These findings are consistent with data showing time-dependent reduction in neutralizing antibody titers after vaccination.^9,10

In our cohort of 70 patients of men who have sex with men (MSM) with mpox, more than one-third presented with proctitis. In two-thirds of proctitis patients, there was no typical rash upon presentation, and in one-fifth, there was no rash at all, making the diagnosis a challenge. A rectal swab for mpox polymerase chain reaction (PCR) can be diagnostic.

Background: Nocardia cyriacigeorgica was first described in 2001. It is an emerging pathogen that mainly affects immunocompromised patients. A brain abscess caused by N. cyriacigeorgica has been reported only in immunocompromised hosts. We present a rare case of brain abscess caused by N. cyriacigeorgica in an adult male receiving low dose steroids.Case presentation: A 75-year-old male weekend gardener without an immunocompromising condition presented with neurological complaints that were initially attributed to an ischemic stroke. Due to the unusual presentation and rapid progression, his condition was thought to be caused by a cerebral space-occupying lesion. He underwent an emergent right-sided parietal craniotomy and the histopathological report of the specimen was an abscess caused by N. cyriacigeorgica. The patient received appropriate antibiotic treatment and completely recovered without sequelae.Conclusions: Nocardia species are a rare cause of brain abscess in immunocompetent patients. Their clinical presentation can mimic other more common cerebral diseases, such as brain tumors (primary and secondary) and stroke. The possibility of an abscess caused by N. cyriacigeorgica should also be considered in the differential diagnosis in an immunocompetent patient.

This study demonstrated a favorable short-term safety profile after a third dose of the BNT162b2 vaccine among healthcare workers (HCWs). There were more frequent local reactions and less systemic reactions compared to the second dose. The HCWs who reported reactions had higher prebooster titer of anti-S1 antibodies compared to those who reported no reactions.

Background: The coronavirus disease 2019 (COVID-19) pandemic poses many epidemiological challenges. The investigation of nosocomial transmission is usually performed via thorough investigation of an index case and subsequent contact tracing. Notably, this approach has a subjective component, and there is accumulating evidence that whole-genome sequencing of the virus may provide more objective insight. Methods: We report a large nosocomial outbreak in 1 of the medicine departments in our institution. Following intensive epidemiological investigation, we discovered that 1 of the patients involved was suffering from persistent COVID-19 while initially thought to be a recovering patient. She was therefore deemed to be the most likely source of the outbreak. We then performed whole-genome sequencing of the virus of 14 infected individuals involved in the outbreak. Results: Surprisingly, the results of whole-genome sequencing refuted our initial hypothesis. A phylogenetic tree of the samples showed multiple introductions of the virus into the ward, 1 of which led to a cluster of 10 of the infected individuals. Importantly, the results pointed in the direction of a specific index patient that was different from the 1 that arose from our initial investigation. Conclusions: These results underscore the important added value of using whole-genome sequencing in epidemiological investigations as it may reveal unexpected connections between cases and aid in understanding transmission dynamics, especially in the setting of a pandemic where multiple possible index cases exist simultaneously.

Cat scratch disease (CSD), caused by Bartonella henselae, usually presents as regional lymphadenopathy/lymphadenitis, known as typical CSD or as atypical CSD, which includes, among others, neurological manifestations. Serology for anti-B. henselae IgG antibodies is the most commonly used diagnostic tests for CSD. Intravenous immunoglobulin (IVIG) is given for an increasing number of medical conditions and may cause interference with serological testing. We report six patients with neurological manifestations and two patients with Kawasaki disease mimicking typical CSD, mistakenly diagnosed as CSD due to false-positive serology following IVIG therapy. Bartonella IgG serology was positive one to six days after IVIG administration and reverted to negative in seven of eight patients or significantly decreased (1 patient) ≤30 days later. In patients with CSD, IgG titers remained essentially unchanged 15–78 days after the positive serum sample. An additional eight patients treated with IVIG for various conditions were evaluated prospectively. All were seronegative one day pre-IVIG infusion, five patients demonstrated an increase in the IgG titers one to three days after IVIG administration, one interpreted as positive and four as intermediate, whereas three patients remained seronegative, suggesting that false seropositivity after IVIG therapy may not occur in all patients. Treatment with IVIG can result in false-positive serology for B. henselae. Increased awareness to the misleading impact of IVIG is warranted to avoid misinterpretation. Repeat testing can distinguish between true and false serology. Preserving serum samples prior to IVIG administration is suggested.