## Solution

$ grep -v "#" results/vcf/SRR2584866_final_variants.vcf | wc -l
766

There are 766 variants in this file. 

Alternate answers:
$ egrep -v "^#" results/vcf/SRR2584866_final_variants.vcf | wc -l
$ grep -v "##" results/vcf/SRR2584866_final_variants.vcf | wc -l