Acute influenza infection has been reported to be associated with neurological symptoms. However, the long-term consequences of an infection with neurotropic and non-neurotropic influenza A virus (IAV...

Most people who get COVID-19 don't suffer damage to the brain. But some do, and even people who initially get just mild COVID symptoms are vulnerable. COVID's potential to damage the brain is anoth...

Background Severely ill patients might develop an alteration of their immune system called post-aggressive immunosuppression. We sought to assess the risk of ICU-acquired infection and of mortality according to the absolute lymphocyte count at ICU admission and its changes over 3 days. Methods Adults in ICU for at least 3 days with a shock or persistent low blood pressure were extracted from a French ICU database and included. We evaluated the impact of the absolute lymphocyte count at baseline and its change at day 3 on the incidence of ICU-acquired infection and on the 28-day mortality rate. We categorized lymphocytes in 4 groups: above 1.5 × 103 cells/µL; between 1 and 1.5 × 103 cells/µL; between 0.5 and 1 × 103 cells/µL; and below 0.5 × 103 cells/µL. Results A total of 753 patients were included. The median lymphocyte count was 0.8 × 103 cells/µL [0.51–1.29]. A total of 174 (23%) patients developed infections; the 28-day mortality rate was 21% (161/753). Lymphopenia at admission was associated with ICU-acquired infection (p < 0.001) but not with 28-day mortality. Independently of baseline lymphocyte count, the absence of lymphocyte count increase at day 3 was associated with ICU-acquired infection (sub-distribution hazard ratio sHR: 1.37 [1.12–1.67], p = 0.002) and with 28-day mortality (sHR: 1.67 [1.37–2.03], p < 0.0001). Conclusion Lymphopenia at ICU admission and its persistence at day 3 were associated with an increased risk of ICU-acquired infection, while only persisting lymphopenia predicted increased 28-day mortality. The lymphocyte count at ICU admission and at day 3 could be used as a simple and reproductive marker of post-aggressive immunosuppression.

Repeated vaccination is needed to maintain high levels of SARS-CoV-2 immunity in vulnerable populations, but there is concern that it could lead to immune exhaustion. Here, the authors assess the evidence for immune exhaustion following multiple SARS-CoV-2 vaccination three vulnerable population cohorts in Canada.