Not necessarily. We generally recommend close contacts get tested if they become symptomatic during their quarantine period. If a close contact is worried about asymptomatic infection, they should wait to get tested until 5-8 days after their exposure to a positive case.
The St. Charles County Department of Public Health can help make this determination based on symptoms and will assist in scheduling a test for a close contact if they do develop symptoms. A close contact cannot reduce their quarantine period with a negative test result.