Daily persistent headache after a viral illness during a worldwide pandemic may not be a new occurrence: Lessons from the 1890 Russian/Asiatic flu

New daily persistent headache was first documented in the medical literature in the 1980s. The leading trigger is a viral illness. As we navigate our way thru the current SARS-CoV-2 pandemic, looking back at past viral epidemics may help guide us for what to expect in the near future in regard to headaches as a persistent manifestation of the SARS-CoV-2 infection. The 1890 viral pandemic known as the "Russian or Asiatic flu", has extensive documentation about the neurologic sequelae that presented months to years after the pandemic ended. One of the complications was daily persistent headache. There are actually many similarities between the viral presentation of the 1890 pandemic and the current SARS-CoV-2 pandemic, which may then suggest that not only will NDPH be part of the neurological sequelae but a possible key consequence of the SARS-CoV-2 infection.