mRNA-based SARS-CoV-2 Comirnaty vaccine elicits weak and short specific memory B cell response in individuals with no previous infection.

Objectives: The dynamics of the memory B cell (MBC) repertoire after SARS-CoV-2 vaccination is crucial for assessing long-term immunity. We compare spike-specific MBC responses between SARS-CoV-2 unexposed and recovered individuals, and their impact on breakthrough infections during follow-up. Methods: Spike-specific MBC and T cells were quantified at inclusion and after two doses of mRNA vaccine in a longitudinal cohort of 85 naïve and 64 recovered participants (47 with positive serology and 17 with negative serology after infection). Results: At inclusion, there was minimal spike-specific MBC in naïve SARS-CoV-2 individuals. After the second vaccine dose, MBCs were significantly boosted in naïve individuals, but reached a significantly lower level than that observed even in unvaccinated SARS-CoV-2 convalescents (p<0.001). Furthermore, while the secondary memory B cell (MBC) population consisted of 100%, 33%, and 76% IgG+, IgM+, and IgA+ expressing cells, respectively, in the unexposed group, the MBC response showed a significant decrease across all isotypes. Similarly, although secondary specific IgG+, IgM+, and IgA+-MBC isotypes were found in 100%, 39%, and 76% of the unexposed participants, respectively, the magnitude of the MBC levels was significantly lower for all the isotypes compared to convalescents. Interestingly, convalescents without an initial serological response had a lower MBC response, like what found in unexposed subjects. There was an inverse correlation between specific MBCs (r=-0.307; p=0.027), especially for isotype IgA+ (r=-0.279, p=0.045), and the time since the second vaccination dose. Furthermore, during a median follow-up of 434 days (IQR, 339-495), 49 out of 149 individuals (33%) became infected, 29 in naïve and 20 in convalescent individuals, showing a significant correlation between spike-specific MBC magnitude after vaccination and the time for SARS-CoV-2 infection, especially for IgA+/IgG+ MBC isotypes. Conclusions: MBCs were primed by mRNA-based vaccination in most cases, but SARS-CoV-2 naïve individuals had a blunted specific MBC response, and this was associated with a shorter time to breakthrough SARS-CoV-2 infection.

Bursitis por mercurio tras accidente laboral: a propósito de un caso / Bursitis due to Mercury after a work accident: a case report

Auxiliar de enfermería de 28 años que acude al Servicio de Urgencias porque refiere dolor y dificultad para la movilización en rodilla derecha, tras accidente laboral, hace dos días. Refiere que se resbaló mientras transportaba 32 termómetros de mercurio, rompiéndose éstos sobre su rodilla, creando una pequeña herida,siendo la puerta de entrada del metal. En la radiografía, se objetiva el cuerpo extraño metálico, correspondiente a mercurio, en bursa rotuliana. Tras el diagnóstico, se realizó la extracción de la bursa, recuperándose la trabajadora totalmente tras la intervención.Con este caso clínico que aportamos, queremos conocer los efectos del mercurio en la salud de las personas expuestas a dicho metal, estudiar los errores acontecidos en este accidente laboral, valorando cuáles hubieran sido las medidas de actuación preventiva adecuadas para evitar la repetición de este tipo de accidentes y, por último, reflexionar acerca de la relación beneficio-riesgo del uso del mercurio en aparatos de medición en el ámbito sanitario (AU)

A 28-year-old woman, nursing assistant, who attends to emergency service, referring pain and difficulty mobilizing right knee after a work accident two days ago. She relates that slipped while carrying 32 mercury thermometers, breaking them on her knee, creating a small wound, being the gateway to the metal. In the radiograph, we objective a metallic foreign body, corresponding to mercury, in patellar bursa. After the diagnosis, the bursa was extracted, and the worker recovered completely, after surgery.With this case report we bring, we want to know the health effects of mercury in people exposed to this metal, studying the errors occurred in this accident, assessing measures of preventive action that would have been neccesary to preclude recurrence of this type accidents and, finally, think about the risk-benefit balance the use of mercury in measuring devices in healthcare (AU)