Individuals with asymptomatic SARS-CoV-2 infection can unknowingly transmit the virus, yet identifying such subclinical infections in post-vaccinated populations remains challenging. We conducted a longitudinal study of 129 infection-naïve vaccine recipients immunized with various combinations of SARS-CoV-2 spike (S) protein vaccine platforms. Sera were collected before the first dose (v1), at 2 weeks (v7) and 6 months (v8) after the third dose. Taiwan’s first major COVID-19 outbreak occurred between v7 and v8. We measured anti-nucleocapsid (anti-N) and anti-S IgG antibody titers by ELISA and assessed virus-neutralizing activity using live virus and pseudovirus assays. By developing an iterative serial screening method, we identified asymptomatic breakthrough (post-vaccination) infections among unconfirmed cases. Our v7-v8 paired cohort resolved into three distinct groups: confirmed cases (21%), asymptomatic breakthrough infections (17%), and uninfected subjects (62%). In normalized v8 sera, confirmed cases exhibited an anti-S+++ (high) /anti-N+++ (high) phenotype, while uninfected subjects showed an anti-S+ (low)/anti-N+(baseline) phenotype. Statistical analysis validated a distinct asymptomatic group characterized by an antibody profile anti-S++ (intermediate) /anti-N+ (baseline). This approach may enable more accurate estimates of vaccine efficacy and infection prevalence. In a spike-vaccinated population, anti-N antibody is more a potential specific marker for COVID-19 symptomatic disease than an ideal marker for SARS-CoV-2 infection. To our knowledge, this is the first preliminary report of identification of asymptomatic breakthrough infection from a well-vaccinated population using self-matched longitudinal pairs of serum samples.
C. Shih, You-Zhen Liao, Che-Yu Hsu et al.· Journal of Biomedical Scienc...· 0 citations
Background Melioidosis, caused by Burkholderia pseudomallei, is a potentially fatal infection endemic to Southeast Asia and northern Australia. Disseminated disease with bacteremia and multifocal organ involvement carries high mortality, particularly among patients with diabetes mellitus (DM) and hazardous alcohol use. Symmetrical peripheral gangrene (SPG) is a rare complication that may result in permanent disability. Case presentation A 57-year-old man with poorly controlled type 2 DM, chronic alcohol use, and malnutrition presented with septic shock and acute hypoxemic respiratory failure. Imaging revealed cavitary pneumonia and abscesses involving the liver, kidney, and prostate. Two independently collected blood cultures and a prostatic abscess aspirate yielded B. pseudomallei, confirmed through a multistep microbiological workflow with final VITEK 2 identification. The patient required vasopressors, mechanical ventilation, continuous venovenous hemofiltration, intravenous meropenem, and image-guided drainage of the prostatic abscess. Distal cyanosis was present at admission and progressed to dry gangrene of multiple fingers and toes. The symmetric acral distribution and absence of major-vessel obstruction were clinically consistent with SPG. Recurrent hyperkalemia and renal dysfunction prevented continued trimethoprim-sulfamethoxazole therapy, necessitating six months of doxycycline plus amoxicillin-clavulanate. Secondary infection and osteomyelitis of the gangrenous digits required multiple amputations. At follow-up 11 months after completion of eradication therapy, there was no evidence of recurrent melioidosis. Conclusion SPG is a rare but devastating complication of disseminated melioidosis. Prompt antimicrobial therapy, intensive organ support, source control, and early recognition of peripheral ischemia are important. Even after survival and successful treatment, substantial long-term functional disability may persist.
Chen-Hsuan Lin, Ping-Chang Lin, Ching-Yi Tsai et al.· Frontiers in Immunology· 0 citations