Bacterial pneumonia, not flu, blamed in 1918 pandemic deaths.

Bacterial pneumonia and not the flu caused most of the deaths during the 1918 Spanish influenza pandemic, officials from the National Institute of Allergy and Infectious Diseases (NIAID) reported.

Viral damage followed by bacterial pneumonia led to the vast majority of deaths, NIAID officials said in a new report published online recently in the Journal of Infectious Diseases.

The pneumonia was caused when bacteria that normally inhabit the nose and throat invaded the lungs of patients with influenza along a pathway created when the virus destroyed the cells that line the bronchial tubes and lungs, the government researchers concluded.

"In essence, the virus landed the first blow while bacteria delivered the knockout punch," declared NIAID Director Anthony Fauci.

Despite the availability of data on four pandemics that have occurred over the past 120 years, there has been little information about the causes of death associated with those pandemics.

It has been estimated that as many as 100 million people died worldwide during the 1918-19 pandemic, with about 700,000 of those deaths in the U.S. Based on those figures, U.S. officials have planned for more than 1.9 million excess deaths during a future severe pandemic.

To ensure the U.S. is prepared for the next widespread flu outbreak, the NIAID researchers, including Fauci, set out to answer the question of what actually killed people during the 1918 pandemic as well as the subsequent 1957-58 Asian and 1968-69 Hong Kong flu pandemics.