It would be very hard to tell. The earliest and biggest public health improvements are driven by simple but powerful measures: increased calorie counts, clean water, improved sanitation. Only once these are satisficed do things like health care and immunizations begin to matter at the margin.

Something like malaria nets sounds cheap and simple enough to be a plausible driver. But even then, to a malnourished kid the nutrition probably matters first.

Even extensive efforts, occurring amid improvements on the fundamentals, would probably be lost in the noise.