After the first dose of HiB vaccine is given to a 2-month-old, when can the other doses be scheduled for optimal protection before moving?

The optimal schedule for administering the HiB (Haemophilus influenzae type b) vaccine is essential to ensure that the child develops adequate immunity. Following the initial dose given at 2 months of age, the subsequent doses are typically given as follows: a second dose at 4 months of age, a third dose at 6 months of age, and a final booster dose at 12 to 15 months of age.

Option D outlines this appropriate schedule by indicating the second dose is given 4 weeks after the first dose at 4 months, the third dose again 4 weeks later at 6 months, and then a booster at 12 months. This timing is in line with the recommendations from health authorities, ensuring that the child's immune response is maximized and sustained throughout the first years of life.

In contrast, the other choices suggest timelines that do not align with the recommended intervals. For example, shorter intervals could lead to suboptimal immunity development and potentially necessitate additional doses. The key is that maintaining the recommended spacing enhances the child's ability to build a robust immune response against HiB.