Are coinfections with COVID-19 and influenza low or underreported? An observational study examining current published literature including three new unpublished cases

As the coronavirus disease-2019 (COVID-19) pandemic continues, one major point of uncertainty is the impact this novel pathogen will have during the upcoming 2020 to 2021 flu season. While the influenza virus is a known contributor to human morbidity and mortality, the question of how a coinfection between COVID-19 and influenza might manifest is of utmost concern. The aim of this study was to review the limited cases of COVID-19/influenza coinfection currently available in the literature, along with cases in the community of El Paso, TX, to determine whether any patterns of clinical presentation and morbidity emerged. An international review of the literature was conducted. Six published articles describing COVID-19/influenza coinfection were identified, with a total of 13 patients described therein. Three additional patients were identified from the El Paso, TX data. The most common presenting symptoms were fever and cough. The most common laboratory findings were elevated C-reactive protein and lymphocytopenia. Thirteen patients presented with viral pneumonia findings on CT, and nine had findings of ground-glass opacity. Finally, complications were reported in six patients, with most common complication being acute respiratory distress syndrome. The results of the review indicate that, due to the similarity in presentation between COVID-19 and influenza, further analysis will be required to understand the effects of coinfection on morbidity and mortality. However, the limited number of coinfection cases in the literature indicates that the implementation of COVID-19 control measures may continue to play a role in limiting the spread of these human respiratory pathogens.