In the three-week period from July 28 to August 17, 2131 people were tested for the virus, while in the three weeks from August 18 to September 7, only 1023 were tested.
This equates to a 52 per cent slump in the number of people tested.
GV Health chief executive Matt Sharp said the reduction was "concerning".
"It indicates people may not be as vigilant as required regarding the need to get tested for COVID-19," he said.
"It is possible people are becoming complacent.
"Even the very mildest of symptoms that are similar to cold and flu symptoms can mean you have COVID-19."
Mr Sharp reiterated anyone unwell with any symptoms of COVID-19, no matter how mild, should get tested immediately and stay home until they receive a result.
Symptoms include fever, chills, cough, sore throat, runny nose and loss of sense of smell.
"Do not go about your normal day-to-day activities such as work or going out in the community," Mr Sharp said.
"Please do the right thing and do not place your family members, friends and the broader community at risk.
"It is important that people get tested so that we know what the prevalence of COVID-19 is in the community."
There is still only one active case of COVID-19 in Greater Shepparton.
One patient with COVID-19 is currently admitted at Goulburn Valley Health.
There are no people in the Mitchell, Benalla, Campaspe, Moira and Strathbogie regions that have tested positive for COVID-19 that are considered to be an active case.
While a new active case of COVID-19 was recorded in Campaspe Shire in Thursday's numbers, the Public Health Unit Bendigo have confirmed it was a false positive test due to a rare laboratory error.
Victoria recorded 43 new cases of COVID-19 and nine deaths on Friday.
GV Health's Acute Respiratory Clinic at Graham St, Shepparton, is open seven days a week from 10 am to 5.30 pm and does not require an appointment.
For more information, phone the coronavirus hotline on 1800 675 398 or visit www.dhhs.vic.gov.au/coronavirus
