Study design
To evaluate whether coinfection with other respiratory viruses is associated with greater severity of COVID-19 cases in Mexico, we analysed samples of pharyngeal exudate received by the Central Laboratory of Epidemiology (CLE) that tested positive for SARS-CoV-2. As of March 30, 2020, CLE had received 1915 samples of suspected cases of COVID-19, of which 277 were positive. Of these, 103 had sufficient biological material to carry out the identification by RT-qPCR of another 16 respiratory viruses (human respiratory syncytial virus (HRSV), human parainfluenza viruses 1-4 (HPIV1-4), influenza virus A (Inf A), influenza B virus (Inf B), human mastadenovirus (HMdV), rhinovirus (RV), enterovirus (EV), human metapneumovirus (HMpV), primate bocaparvovirus (PBpV), HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1).
Other factors that could contribute to the increased severity of the cases analysed were evaluated, such as age, sex, the presence of comorbidities (diabetes, hypertension, chronic kidney disease, chronic liver disease, chronic obstructive pulmonary disease (COPD), asthma, obesity, and haemolytic anaemia), and viral load at the onset of symptoms.
All 103 samples analysed had a previous positive result for SARS-CoV-2 by RT-qPCR and met the following case definition: a person of any age who in the last 7 days presented with at least two of cough, fever, and headache, accompanied by at least one of dyspnoea (severity data), arthralgias, myalgias, odynophagia/pharyngeal burning, rhinorrhoea, conjunctivitis, and chest pain. The other inclusion criterion was that the data on the patient’s initial clinical condition at the time of sample collection and the final outcome of the disease were available.