Intermittent or persistent fever is one of the most common presentations of Coronavirus disease (COVID-19). Typically, this fever is low grade and rises on walking or climbing stairs. The patient complains of feeling feverish at rest, but the clinical thermometer does not show a fever. Often, fever is noticed for the first time when the patient is undergoing a 6-minute walk test (6MWT).
COVID-19 fever may be seen in children, adults or elderly. The fever is often intermittent, it comes and goes. An atypical observation is that in women, the fever disappears during menstruation and then returns.
Fever in a COVID-19 patient may be of two types. One, is inflammatory fever, not infectious fever, where the body temperature may rise to depending on the increase in acute phase reactants and presence or absence of underlying pneumonia.
The second type is the low grade fever, which appears only during the day, either in the afternoon or in the evening, and occurs after exertion. It is due to the dysregulation of the body’s thermostat. Hence, screening for fever during the morning may miss potential COVID-19 patients. The fever is usually less than 1000F. This pattern of fever will be included in the differential diagnosis of evening rise of fever as seen in tuberculosis (TB). The patient may have chills, but no rigors.
If the patient has fever with high ESR and CRP levels, anti-inflammatory drugs are indicated. Since this fever is inflammatory in nature, it does not respond to paracetamol even though the fever is low grade. Instead, the fever responds better to responds to anti-inflammatory drugs like mefenamic acid, naproxen, nimesulide and indomethacin.
The fever may persist after 9 days of onset of illness; this is typically the post-COVID phase, which can be with or without rise in acute phase reactants. These patients have persistent systemic inflammation. The fever may sometimes persist for as long as 3 months.