Research on psychological risk factors for upper respiratory tract illnesses (URTIs) has been conducted for over fifty years. Early studies failed to control for exposure and also often relied on self-report rather than clinical and virological assessment. A universal policy used in the current COVID-19 pandemic has been to restrict exposure by social isolation. This leads to increased stress and removal of social interaction. In addition, information overload about the disease, and incorrect information, can also reduce wellbeing. Studies of experimentally-induced URTIs have shown that stress increases susceptibility to infection. Other research has shown that stress due to job insecurity and few social contacts are key risk factors for infection. This suggests that while social isolation will reduce exposure, it will also lead to an increased risk of illnesses, due to increased stress and reduced social support, should the person become infected with the virus. Other research has shown that infection and illness lead to changes in behaviour. These effects include greater negative affect and impaired attention and slower speed of response. Such effects are not only present when the person is symptomatic but also occur with sub-clinical infections, during the incubation period and after the illness. People with the illness are also more sensitive to other negative influences such as fatigue, and this has implications for safety critical jobs such as those carried out by healthcare professionals treating those with COVID-19.