*For the purpose of this guidance, fever is defined as subjective fever (feeling feverish) or a measured temperature of 100.4oF (38oC) or higher. Note that fever may be intermittent or may not be present in some people, such as those who are elderly, immunosuppressed, or taking certain medications (e.g., NSAIDs).
** Data are limited to define of close contact. Factors to consider when defining close contact include proximity, the duration of exposure (e.g., longer exposure time likely increases exposure risk), whether the individual has symptoms (e.g., coughing likely increases exposure risk) and whether the individual was wearing a facemask (which can efficiently block respiratory secretions from contaminating others and the environment).
***Data are insufficient to precisely define the duration of time that constitutes a prolonged exposure. Recommendations vary on the length of time of exposure from 10 minutes or more to 30 minutes or more. In healthcare settings, it is reasonable to define a prolonged exposure as any exposure greater than a few minutes because the contact is someone who is ill. Brief interactions are less likely to result in transmission; however, symptoms and the type of interaction (e.g., did the person cough directly into the face of the individual) remain important.
Integration of these definitions and actions into communications and actions of public health authorities can be guided by CDC’s “Implementation of Mitigation Strategies for Communities with Local COVID-19 Transmissionpdf icon”