Asia is considered an important source of influenza A virus (IAV) pandemics, owing to large, diverse viral reservoirs in poultry and swine. However, the zoonotic origins of the 2009 A/H1N1 influenza pandemic virus (pdmH1N1) remain unclear, due to conflicting evidence from swine and humans. There is strong evidence that the first human outbreak of pdmH1N1 occurred in Mexico in early 2009. However, no related swine viruses have been detected in Mexico or any part of the Americas, and to date the most closely related ancestor viruses were identified in Asian swine. Here, we use 58 new whole-genome sequences from IAVs collected in Mexican swine to establish that the swine virus responsible for the 2009 pandemic evolved in central Mexico. This finding highlights how the 2009 pandemic arose from a region not considered a pandemic risk, owing to an expansion of IAV diversity in swine resulting from long-distance live swine trade.DOI: http://dx.doi.org/10.7554/eLife.16777.001

Several highly efficacious vaccines for SARS-CoV-2 have been developed and are used in the population. However, the current production capacity cannot meet the global demand. Therefore, additional vaccines—especially ones that can be produced locally and at low cost—are urgently needed. This work describes preclinical testing of a SARS-CoV-2 vaccine candidate which meets these criteria.

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