Tens of billions of antibodies were screened, resulting in the identification of 10 that target an 'Achilles heel' present in most harmful forms of influenza.
New drug treatments based on the proteins could be several years away but, if successful, they would have the potential to save thousands if not millions of lives during a serious flu pandemic.
It should be possible to quickly make large numbers of the synthetic monoclonal' antibodies and rapidly deploy them during the four to six months it would take to produce a suitable vaccine.
Researcher Dr Wayne Marasco, from the Dana-Farber Cancer Institute and Harvard Medical School in Boston, said: 'There are clear settings where human monoclonal antibodies can be used strategically for both the prevention and early treatment of influenza infection and disease.
'At-risk individuals, such as first responders and medical personnel, exposed family members and co-workers and patients who cannot make antibodies because of pre-existing medical conditions or advanced age, could all benefit from this new type of therapy.'
The research is published in the journal Nature Structural & Molecular Biology.
Related article: Flu response will draft in students