@danluu Yeah, there's some evidence that having covid results in lower lymphocyte levels afterwards - this effect isn't specific to RSV. "Previous studies have reported T-cell exhaustion and a decline in effector memory CD4+ and CD8+ T cells lasting at least 13 months after mild COVID-19. Our findings extend this observation, demonstrating that even a short, widespread SARS-CoV-2 outbreak can lead to prolonged lymphocyte dysregulation, which is potentially driven by impaired T-cell maturation, increased apoptosis, or prolonged immune activation. ... "Such alterations may impair the immune system’s ability to mount an effective response against latent infections, thereby increasing susceptibility to opportunistic pathogens." https://www.sciencedirect.com/science/article/pii/S1201971225005090