On Doctoring MEDLINE searches, with reference librarian comments

The question was

"A look at Polio and studies done on Polio
immunization and/or vaccination programs in Africa"

1 :  exp brain diseases/ and exp poliomyelitis/ and         {59}
Poliomyelitis, bulbar/
2 :  limit 1 to (local holdings and human and english language)         {29}
3 :  limit 2 to yr=1990-1999         {10}
4 :  exp immunization programs/ or Preventive health services/         {5304}
5 :  3 and 4         {0}
6 :  limit 5 to english language         {0}
7 :  limit 6 to (local holdings and human and english language)         {0}
8 :  4         {5304}
9 :  limit 8 to (local holdings and human and english language)         {2570}
10 :  limit 9 to yr=1990-1999         {1556}
11 :  limit 10 to ebm reviews         {5}
12 :  exp Poliomyelitis/         {5232}
13 :  Immunization/         {27033}
14 :  12 and 13         {260}
15 :  limit 14 to (local holdings and human and english language)         {161}
16 :  limit 15 to yr=1990-1999         {39}
17 :  exp Vaccines/         {62861}
18 :  12 and 17         {1749}
19 :  limit 18 to (local holdings and human and english language         {374}
and yr=1990-1999)
20 :  exp Africa/         {71890}
21 :  (16 or 19) and 20         {44}
22 :  from 21 keep 1-3,6,13,15-16,18-20,22,24-25,31,37,41-42         {17}
23 :  from 21 keep 42         {1}
24 :  from 21 keep 1-3,13,15-16,18-20,25,31,42         {12}
25 :  from 24 keep 1-12          {12}

Reference Librarian comments

I'm sure you now understand why set #1 was a disaster. You were
ANDing those subjects, getting more restrictive with every thought.
You were doing good Medline experimentation. At set #12, you're on
the right track. Great job. When you've searched for 20 years, you
can get it down to a terse, haiku-like shortness, like this:

1 :  exp *poliomyelitis/pc,ep [Prevention and control; Epidemiology]
2 :  exp africa/
3 :  1 and 2 (79 references)