Critical Zabbix agent does not enable vmstat statistic collecting by default only if vmstat items are enabled. It waits 2 seconds till new data, but it could be not enough to calculate and gather data during these 2 seconds (2 iterations of collector):
3473522:20161115:125158.799 using configuration file: /opt/zabbix/etc/zabbix_agentd.conf 3473522:20161115:125158.799 agent #0 started [main process] 17498270:20161115:125158.800 agent #1 started [collector] 15859782:20161115:125158.803 agent #2 started [listener #1] 11862088:20161115:125158.804 agent #3 started [active checks #1] 11862088:20161115:125200.830 active check "system.stat[cpu,id]" is not supported: No data available in collector.