A 6-year-old girl is admitted to the hospital with fever, headache, and neck stiffness. A lumbar puncture yields cloudy cerebrospinal fluid with a neutrophil predominance. Gram stain shows Gram-negative diplococci. Further testing confirms Neisseria meningitidis. This pathogen is known to have a polysaccharide capsule. Which of the following best describes how the capsule enhances the bacterium's ability to evade the host immune response?