grep -c value NH:i:1 only for every line in file, not also NH:i:12 - regex

Question

cat samtry.txt | grep -c NH:i:1
See an example of three lines below. the bold information is whats important
HWI-ST697:178:D1U9CACXX:1:2111:12787:5687 153 scaffold_1 33005 50 101M * 0 0 GACTAAGGAAGTCATCTGCAGTGCCCCTTGCACTTCCTAATGGGACTTTCCCTGGTTGACTATTCTTACTATGAGAACAATGAGCACCAGCTTCATTCACA DCDDDDDDDDDDDEEEEEEEEFGHGJIHGHFHJIJIJJIJJJJIHJJIJIIIFJJIGGGIJJJIIJJHIGJIJJJGHJJIJIJIGFJJGHHHHFFFFFCCC AS:i:-11 XN:i:0 XM:i:2 XO:i:0 XG:i:0 NM:i:2 MD:Z:18T26G55YT:Z:UU **NH:i:1**
HWI-ST697:178:D1U9CACXX:3:1310:18383:72540 89 scaffold_1 33005 50 101M * 0 0 GACTAAGGAAGTCATCTGCAGTGCCCCTTGCACTTCCTAATGGGACTTTCCCTGGTTGACTATTCTTACTATGAGAACAATGAGCACCAGCTTCATTCACA DDDDDDDDDDDDDEEEEEEFFFHHHIIJJIIIJIJJJJJJJJJJHJJJJJJJJJJJJJIJJJJJJJJIJJJIJJIJJJJJJJJIHFJJHHHHHFFFFFCCC AS:i:-11 XN:i:0 XM:i:2 XO:i:0 XG:i:0 NM:i:2 MD:Z:18T26G55YT:Z:UU **NH:i:11**
HWI-ST697:178:D1U9CACXX:7:1212:17559:76798 89 scaffold_1 33007 50 101M * 0 0 CTAAGGAAGTCATCTGCAGTGCCCCTTGCACTTCCTAATGGGACTTTCCCTGGTTGACTATTCTTACTATGAGAACAATGAGCACCAGCTTCATTCACAAG DDDDDDDDDDDDDEEEECDFFHGHIGJIIHJJJIIJJJJJJHHJJJJJJJJJJJIIIJJJJGIIGBJJIJJJJIJJJJJIHHHFJJIJHHHHGFFFFFCCC AS:i:-11 XN:i:0 XM:i:2 XO:i:0 XG:i:0 NM:i:2 MD:Z:16T26G57YT:Z:UU **NH:i:1**
I am trying to use a shell script to count all the lines in a tab-delimited-file (testfile: samtry.txt, contains 10 lines to test on) that contains the following Regular expression NH:i:1
The problem is of course that I get the information I wanted; but it also counts the lines with the following outcome: NH:i:1x (where x is any possible digit: 0-9)
The position of the NH:i:x (x = any digit until around 50) is in every line of the file on 20, its not the last position of the line. Every line has 23 'positions'.
Does anyone know how to do this with grep or another tool?
I've got around 100 files which each have a size of around 3GB each, and I don't know how to solve this problem
I hope I give enough information, I am happy for every answer

Answer 1

Try grep with word boundaries:
grep -c '\<NH:i:1\>' samtry.txt
OR grep -w:
grep -wc 'NH:i:1' samtry.txt