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Volume 32, Number 6—June 2026

Online Report

Assessing Evidence to Guide Primary Prevention of Pathogen X

Iris HolmesComments to Author , Neil M. Vora, Emily S. Gurley, Latiffah Hassan, Wanda Markotter, James O. Lloyd-Smith1, and Raina K. Plowright1
Author affiliation: Cornell University College of Veterinary Medicine, Ithaca, New York, USA (I. Holmes, R.K. Plowright); School of Biological Sciences, Southern Illinois University, Carbondale, Illinois, USA (I. Holmes); Preventing Pandemics at the Source Coalition, New York, New York, USA (N.M. Vora); Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA (E.S. Gurley); University of Missouri, Columbia, Missouri, USA (L. Hassan); University of Pretoria, Pretoria, South Africa (W. Markotter); University of California Los Angeles, Los Angeles, California, USA (J.O. Lloyd-Smith).

Main Article

Figure

Conceptual framework for the frequency of spillover versus potential for human-to-human transmission to assess evidence to guide primary prevention of Pathogen X. Zoonotic viruses are positioned along 2 axes: spillover frequency and human-to-human spread. The y-axis line represents the boundary between viruses capable of sustained spread among humans (R>1), versus those with limited or no onward spread (R<1). The x-axis represents a relative, rather than 1-to-1, mapping of R for the example viruses. Viruses that are not known to spread human-to-human are shown at the far left of the plot. Pathogen X represents a hypothetical pandemic-capable virus and occupies the rare spillover/spreads well quadrant. MERS, Middle East respiratory syndrome; MPXV, monkeypox virus; pH1N1, pandemic H1N1.

Figure. Conceptual framework for the frequency of spillover versus potential for human-to-human transmission to assess evidence to guide primary prevention of Pathogen X. Zoonotic viruses are positioned along 2 axes: spillover frequency and human-to-human spread. The y-axis line represents the boundary between viruses capable of sustained spread among humans (R>1), versus those with limited or no onward spread (R<1). The x-axis represents a relative, rather than 1-to-1, mapping of R for the example viruses. Viruses that are not known to spread human-to-human are shown at the far left of the plot. Pathogen X represents a hypothetical pandemic-capable virus and occupies the rare spillover/spreads well quadrant. MERS, Middle East respiratory syndrome; MPXV, monkeypox virus; pH1N1, pandemic H1N1.

Main Article

1These senior authors contributed equally to this article.

Page created: April 30, 2026
Page updated: June 01, 2026
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