 (3) The impact of under-reporting cases on the early stages of the pandemic is greater than that on its later stages, and the impact on the early onset area is greater than that on the late onset area.
<fluency>  (3) The impact of under-reporting cases on the early stages of the pandemic is greater than that on its later stages, and the impact on the early onset area is greater than that on the late onset area.
 (3) The impact of under-reporting cases on the early stages of the pandemic was greater than that on its later stages, and the impact on the early onset area is greater than that on the late onset area.