Immunological imprinting by ancestral SARS-CoV-2 strains is thought to impede the robust induction of Omicron-specific humoral responses by Omicron-based booster vaccines. Here, we analyzed the specificity and neutralization activity of memory B (B _mem ) cells after repeated BA.5 exposure in individuals previously imprinted by ancestral strain–based mRNA vaccines. After a second BA.5 exposure, B _mem cells with BA.5 spike protein–skewed reactivity were promptly elicited, correlating with preexisting antibody titers. Clonal lineage analysis identified BA.5-skewed B _mem cells that had redirected their specificity from the ancestral strain to BA.5 through somatic hypermutations. Moreover, B _mem cells with redirected BA.5 specificity exhibited accelerated development compared with de novo B _mem cells derived from naïve repertoires. This redirected BA.5 specificity demonstrated greater resilience to viral point mutation and adaptation to recent Omicron variants HK.3 and JN.1, months after the second BA.5 exposure, suggesting that existing B _mem cells elicited by older vaccines can redirect their specificity toward newly evolving variants.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak is rising globally. However, clinically effective antiviral treatments are not established. Favipiravir may prevent pneumonia and acute respiratory distress syndrome aggravation. We describe SARS-CoV-2-positive patients, two of whom were in a critical condition and one of whom was in a severe condition, who were administered favipiravir for their deteriorating conditions and cured.

To determine the false-negative rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse-transcription polymerase chain reaction (RT-PCR) test results, and to describe the characteristics of coronavirus disease 2019 (COVID-19) patients with false-negative results. We validated SARS-CoV-2-positive RT-PCR test results performed in hospitalized patients between February 1 and August 31, 2020 and classified the patients according to disease severity. In total, 2038 SARS-CoV-2 RT-PCR tests were performed on 1890 patients. Of these, 145 patients had positive results and were diagnosed with COVID-19. Among the 145 patients with COVID-19, the initial RT-PCR tests were negative in five patients. Of these, three had moderate illness and were initially tested in the early stage of disease, and two had severe illness and were initially tested in the late stage of disease, when RT-PCR testing has lower sensitivity due to viral clearance. These findings suggest that false-negative results can be caused by both observer errors and by low viral RNA levels in the later stages of disease, after the infection has cleared. Clinicians should be aware that patients with COVID-19 can have negative RT-PCR test results in the later stages of infection.

A case of 51-year-old male with painful legs and moving toes syndrome was successfully treated with epidural spinal cord stimulation. He was previously treated with varieties of medication, epidural block, transcutaneous nerve stimulation, lumbar sympathetic block, with no or only a transient effect. Epidural spinal cord stimulation was applied by means of percutaneously inserted epidural electrodes connected to a percutaneous extension for 2-week test stimulation period and later to a permanent device (ITREL). Pain and involuntary movement were relieved almost completely during the stimulation and the effect was still evident 6 months later.

Introduction: COVID‐19 pandemic led to significant reductions in influenza detection worldwide, fueling debates on whether influenza truly ceased circulating in communities. The number of influenza cases decreased significantly in Japan, raising concerns about the potential risk of decreased immunity to influenza in the population. Our single‐center study aimed to investigate influenza trends before and during the COVID‐19 pandemic in Tokyo, Japan.Materials and Methods: This cross‐sectional study included patients of all ages who visited Tokyo Shinagawa Hospital between April 1, 2018, and March 31, 2023. Influenza and COVID‐19 tests were conducted using Quick Navi‐Flu2 and polymerase chain reaction (PCR). We analyzed data from before and during the COVID‐19 epidemic, based on patient background, hospitalization, and deaths, collected from medical records.Results: A total of 12 577 influenza tests were conducted, with approximately 100 tests consistently performed each month even in the influenza off‐season. Throughout the observation period, 962 positive cases were identified. However, no cases were observed for 27 months between March 2020 and November 2022. Influenza A cases were reobserved in December 2022, followed by influenza B cases in March 2023, similar to the influenza incidence reports from Tokyo. The positivity rate during the 2022–2023 winter season was lower than before the COVID‐19 epidemic and decreased in elderly patients, with no hospitalizations or deaths observed.Conclusion: This single‐center study provided actual trend data for influenza patients before and during COVID‐19 outbreaks in Tokyo, which could offer insights into the potential impact and likelihood of influenza virus infection in Japan.

We report the cases of two patients with secondary hemophagocytic lymphohistiocytosis caused by immune checkpoint inhibitors, who were diagnosed using the recently developed HScore. The first patient presented with fever, cytopenia, and elevated liver enzyme levels at 46 days post‐pembrolizumab administration. The HScore was 175. The second patient developed an immune‐related adverse event at 30 days after the final pembrolizumab dose. The HScore was 185. Hemophagocytic lymphohistiocytosis was confirmed in both patients, and corticotherapy improved their condition. It is challenging to diagnose hemophagocytic lymphohistiocytosis, particularly after development at a late stage. Our patients developed hemophagocytic lymphohistiocytosis late after immune checkpoint inhibitor administration. However, the HScore enabled us to diagnose both cases precisely and in a timely manner.