COVID-19 vaccine immunogenicity and safety surrounding fourth and subsequent vaccine doses in patients with hematologic malignancies.

BACKGROUND: Immune response to COVID-19 vaccine is diminished in patients with hematologic malignancy. There is limited data regarding response to vaccine doses in these patients. PURPOSE: To quantify the humoral immune response engendered by 4th and subsequent doses of SARS-CoV-2 vaccination as measured by anti-Spike (anti-S) antibody levels, based on dried blood spot (DBS) testing, in patients with hematologic malignancies. Anti-S binds to the spike protein of the SARS-CoV-2 virus and is indicative of vaccine immunogenicity. METHODS: We conducted a prospective study of hematologic malignancies between August 2021 and January 2023 at 12 sites across Canada. Participants were followed longitudinally and submitted finger-prick DBS cards at set intervals associated with vaccination. Samples were processed via high throughput ELISA assay to detect serum antibodies against nucleocapsid (N) and spike (S) proteins. RESULTS: We obtained 3071 samples on 790 unique patients. Of these, 372 unique participants with 1840 samples had anti-S results available post-4th, 5th or 6th COVID-19 vaccine dose and were included for analysis. Three hundred thirty-three patients of the 372 participants submitted a DBS sample post 4th dose. Of these, 257 patients (77.2%) had a positive anti-S antibody. A total of 198 patients had paired samples pre- and post-dose 4, of which 59 (29.7%) had a negative anti-S antibody pre-dose 4. Of these, 20 (33.4%) developed positive anti-S antibody post-dose 4. One hundred forty-nine patients submitted a DBS sample post-dose 5. Of these, 135 patients (90.6%) had positive anti-S antibody. A total of 52 had paired samples pre- and post-dose 5. Six (8.7%) had a negative anti-S antibody pre-dose 5, of which two (33.3%) developed positive anti-S antibody post-dose 5. Of these 372 patients, 123 (34%) reported COVID-19 infection and 4 (1%) had a COVID-19 related hospitalization. There were no reported deaths from COVID-19. CONCLUSIONS: This prospective cohort study showed that humoral immune response improved with subsequent doses of COVID-19 vaccines.

Activity, boldness and schooling in freshwater fish are affected by river salinization.

Rivers are experiencing increasing anthropogenic pressures and salinity has shown to affect freshwater fish behaviour, potentially disrupting ecological processes. In this study, the aim was to determine the sub-lethal effects of salinization on freshwater fish behaviour, using a widespread native cyprinid species, the Iberian barbel (Luciobarbus bocagei) as the model species. Behavioural trials in a mesocosms setting were performed to assess the effects of three levels of a salinity gradient - control (no salt added to the water, 0.8 mS/cm), low (9 mS/cm), and high concentration (18 mS/cm) - on fish routine activity, shoal cohesion and boldness. Upon increasing the salinity levels in the flume-channels, fish showed a significant reduction on their i) swimming activity (76% of searching behaviour in the control vs. 57% in high salinity), and ii) shoal cohesion (0.95 shoal cohesion ratio in the control vs. 0.76 in high salinity), while iii) an increase of bolder individuals, measured by a higher number of attempts to escape the altered environment (106 total jumps in the control vs. 262 in high salinity), was simultaneously observed. Behavioural changes in fish can reflect shifts in ecological condition. Thus, the behavioural responses of fish caused by salinization stress should be further researched, in addition to the interaction with other environmental stressors, in order to understand the true scope of the consequences of salinization for fish species.

Does short-term salinization of freshwater alter the behaviour of the Iberian barbel (Luciobarbus bocagei, Steindachner 1864)?

Stream salinization is a great environmental hazard being aggravated by anthropogenic disturbances. Harmful conditions, as increasing salinity in freshwater systems, may negatively affect river fish fauna and possibly influence fish behaviour, such as boldness and/or cerebral lateralization. Salinity has been proven to affect behavioural expression, despite the tolerance of some species. It is thus relevant to study these behaviours, as the salinity exposure effects could represent greater environmental consequences. The impact of salinity stress was evaluated by exposing Iberian barbels, Luciobarbus bocagei (Steindachner, 1864) (Cypriniformes, Cyprinidae), to three levels of salinity (0.9, 9 and 19 mS/cm, using NaCl) and by conducting boldness and lateralization experiments, regarding population trends. Results show that, with increased salinity, fish diverged to the extremes of the shy-bold gradient, the population was slightly lateralized to the left, and seemed to become more lateralized with increasing salinity. However, there were no statistical differences between the treatments. Fish living in a Mediterranean climate are especially resilient to various stressors, which may confer them additional tolerance, and in this case, acute punctual exposure to increased salinity may not be detrimental for behaviour maintenance. We encourage the expansion of the research to different freshwater fish species that would help to recognise salinity thresholds and use them to implement effective conservation measures and appropriate ecological restoration actions for these sensible systems.