Epidemiology

Internal medicine

Viral pneumonia

Disease

Streptococcus pneumoniae

Coronavirus disease 2019 (COVID-19)

Antibiotics

Infectious disease (medical specialty)

Biology

Microbiology

Pandemic

Outbreak

Virology

Bacterial pneumonia

Immunology

Pneumonia

Medicine

The Lancet Microbe

Respiratory viral infections predispose patients to co-infections and these lead to increased disease severity and mortality. Most fatalities in the 1918 influenza outbreak were due to subsequent bacterial infection, particularly with Streptococcus pneumoniae.1 Poor outcomes in the 2009 H1N1 influenza pandemic were also associated with bacterial co-infections, although few studies captured these data.2

Co-infections: potentially lethal and unexplored in COVID-19