Purpose: To determine whether the post-vaccination symptoms and symptom severities of the SARS-CoV-2 vaccine are associated with the anti-spike protein antibody (S antibody) titer.

Methods: Study participants were 287 university sports club members (244 males, 43 females; median age 20 years) who had received Moderna's vaccine. We identified, through participant-completed questionnaires, the presence or absence of vaccine-associated symptoms, including headache, chills/shivering, muscle pain, joint pain, injection-site pain, injection-site swelling, rash or itching, and sore throat. Severity was evaluated using a 4-grade score for fever and a 5-grade score for other side effects. Anti-nucleocapsid protein antibody (N antibody) and S antibody were measured using serum collected after the second vaccination.

Results: More than 40% of patients experienced malaise, muscle pain, and pain at the injection site after the first injection. Fever, malaise, headache, chills/shivering, arthralgia, and injection-site pain and swelling were significantly frequent in the second injection compared with the first. Comparing post-vaccination symptoms between N antibody-negative (207 [72.1%]) and -positive participants (80 [27.9%]), the frequency of fever, malaise, chills, and tremors was higher in the N antibody-positive group after the first dose. The S antibody titer in the N antibody-negative participants ranged between 2,815 and 5,283 U/mL (median, 3,970 U/mL). No clear association was observed between symptom severity and S antibody titer, nor between symptom scores other than fever and the S antibody titer.

Conclusion: Post-vaccination symptoms were more frequently observed after the second injection. Post-vaccination symptoms after the first injection were frequent among N antibody-positive participants. There was no relationship between the severity of vaccine-associated symptoms and the vaccine-induced S antibody titers.

A 69-year-old woman first presented to another hospital 2 months earlier with a cough for 2 months. Chest X-ray revealed a tumor in the right upper lobe and computed tomography (CT) of the chest suggested lung abscess. Antibiotics were administered orally for 3 weeks, but her condition did not improve. She developed hemoptysis intermittently and the lung tumor increased in size. She was referred to our department. Although transbronchial lung biopsy and CT-guided lung biopsy were performed, a definitive diagnosis could not be made. The tumor temporarily shrunk but increased again in size. Five months after referral, she underwent thoracoscopic resection of the right S² segment. Pathological specimens revealed bronchocentric necrotizing granulomatous lesions and marked lymphatic follicles with germinal centers. Conventional bacterial culture detected no bacteria, acid-fast bacilli, or fungi, but anaerobic culture detected Parvimonas micra and re-examination of the pathological specimens revealed clusters of gram-positive cocci. We thus concluded that in this case P. micra, a gram-positive anaerobic coccus, was the causative pathogen of bronchocentric necrotizing granulomatosis.

Purpose: To report a case of paraganglioma that mimicked a duodenal tumor. Case report: A woman in her 70’s underwent a coronary CT examination whereupon a paraduodenal tumor was discovered. A dedicated contrast-enhanced abdominal CT demonstrated a well-defined mass that partially abutted the duodenum. The tumor showed avid contrast enhancement in the arterial phase; the contrast enhancement lasted until the venous phase. MRI showed cysts within the tumor, and the T2-weighted image showed heterogeneous hyperintensity. There were dot-like and linear hypointense regions, suggesting a signal void due to rapid flow in the tumor. As a hypervascular tumor containing areas of cystic degeneration, retroperitoneal paraganglioma was a possible differential diagnosis. ¹²³I-MIBG scintigraphy showed significant uptake at the site of the tumor. After surgery, the histopathological diagnosis was paraganglioma, consistent with the clinical diagnosis. Discussion: Avid contrast enhancement in the arterial phase and cystic degeneration in the tumor are typical features of paraganglioma, duodenal gastrointestinal stromal tumors, and pancreatic neuroendocrine tumors. Sympathetic ganglia exist in the periarterial space of the renal artery, and consequently, paragangliomas can occur in this area. Paraganglioma should be included in the list of differential diagnoses for paraduodenal tumors. Conclusion: Paraganglioma should be included in the list of differential diagnoses for a hypervascular retroperitoneal tumor near the duodenum that exhibits a contrast enhancement in the arterial phase. Discovery of endocrine abnormality may assist diagnosis, and ¹²³I-MIBG scintigraphy is necessary to reach a diagnosis of paraganglioma.

Objective: For the management of novel coronavirus disease 2019 (COVID-19), antibody tests have been developed targeting the SARS-CoV-2 nucleocapsid protein (N antigen) and spike protein S1 domain (S antigen). In this study, we measured the N and S antibody titers before and after coronavirus vaccination in members of a sports club that had a COVID-19 outbreak and compared them to those of a sports club that did not have an outbreak at the same university. Furthermore, we investigated the characteristics of the two antibodies.

Subjects and methods: The subjects were 118 A club members that had an outbreak (44 PCR test positives) and 105 B club members that did not have an outbreak (1 PCR test positive). Serum was collected before vaccination and about 1 month after the second vaccination. Significance was assessed using the Mann-Whitney U test.

Results: In A club, the median S antibody titer before vaccination in PCR-positive subjects was 121 U/mL, and that in PCR-negative subjects was 0.4 U/mL (P < 0.001). After vaccination, the median S antibody titer in PCR-positive subjects increased to 38,198 U/mL, which was significantly higher than that in PCR-negative subjects (median: 5,164 U/mL) (P < 0.001). Post-vaccination S antibody titers in all subjects of both clubs were 15 U/mL or more, indicating effective production of neutralizing activity. Before vaccination, 61 A club and 6 B club members were positive for N antibodies. All 45 PCR-positive individuals from both clubs were N antibody-positive. On the other hand, among those who were PCR-negative or not tested, 17 from A club and 5 from B club were positive for N antibody. Pre-vaccination N antibody-positive subjects showed significantly higher post-vaccination S antibody titers than N antibody-negative subjects (P < 0.001).

Conclusion: Our findings suggest that SARS-CoV-2-infected persons generate high S antibody titers after vaccination. As all PCR-positive subjects were N antibody-positive, this antibody is useful for recognizing SARS-CoV-2-preinfected individuals. The presence of PCR-negative and N-antibody-positive patients suggest that multiple PCR tests are necessary for the diagnosis of COVID-19.

Since the novel coronavirus disease (COVID-19) emerged in late 2019 and subsequently evolved into the pandemic, accurate and rapid diagnostic tests of the disease have been developed. Reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP) amplifies target sequences within cDNA using a strand-displacement-type DNA polymerase under a constant reaction temperature and can detect SARS-CoV-2 within 1 hour. In this study, we compared RT-LAMP and the conventional real-time reverse transcription polymerase chain reaction (RT-PCR) in SARS-CoV-2 diagnostic testing. We prepared a 10-fold dilution series of SARS-CoV-2 N-gene synthetic RNA and found that RT-LAMP and real-time RT-PCR detected the gene in up to 10²- and 10³-fold diluted materials, respectively. Next, we randomly selected 12 RT-LAMP-positive nasopharyngeal swabs and prepared a 10-fold dilution series from purified nucleic acids of these specimens. The concordance rate of RT-LAMP and real-time RT-PCR for positive results was 97%. Comparing the threshold time (Tt) value of RT-LAMP and the cycle threshold (Ct) value of real-time RT-PCR, both values showed a positive correlation (correlation coefficient, 0.89, P < 0.001) and samples with a Ct value of 37 cycles or less were detectable with RT-LAMP. Between Ct values of 29-40 cycles and Tt values of 11-20 minutes, the approximation of Ct value = 1.1 × Tt value + 17 could be applied. On the other hand, as the Tt value corresponding to the Ct value of 40 cycles was calculated as 20 minutes and 55 seconds, when the Tt value in RT-LAMP exceeds 20 minutes, we should be cautious of assessing the material as positive.

SARS-CoV-2 continues to spread; thus, information about variants, which may affect the virus’ properties, has become increasingly important for the management of COVID-19. The first SARS-CoV-2 variant in Japan was recognized in December 2020 and the strains detected in the country were replaced by the δ variant carrying the L452R mutation before October 2021. As a newly emergent variant can rapidly propagate, national authorities and local hospitals have to be involved in monitoring and assessing changes to the virus. In this study, we randomly selected a total of 116 SARS-CoV-2 RT-LAMP-positive nasopharyngeal swabs obtained in our hospital between July 2020 and September 2021 and investigated them for the presence of variant strains using RT-pPCR primer/probe sets for detection of N501Y, E484K, and L452R mutations. Of 37 samples obtained during the 3rd wave of the COVID-19 pandemic, 34 (91.9%) were negative for the mutations. On the other hand, of 20 samples obtained during the 4th wave, 11 (55.0%) had N501Y and five (25.0%) had E484K mutations, and of 59 samples obtained during the 5th wave, 28 (47.5%) had N501Y and 29 (49.2%) had L452 mutations. This study indicates that evolution of SARS-CoV-2 observed in a local hospital occurred in a similar pattern to global trends of the spread of the variant strains.