Viral dispersion in open air

Trombini Machado, G.; Ramos de Carvalho Pinto, C.; Villanueva da Fonseca, L. A.; dos Santos Ramos, T. C.; Pereira Paggi, T. F.; Spira, B.

The SARS-CoV-2 pandemic has revived the debate about the routes of virus transmission and their likelihood. It is of utmost importance to assess the risks of contamination of susceptible people by infectious individuals and to evaluate the level of viral transmission in the community. Most countries have imposed non-pharmaceutical measures to contain SARS-CoV-2 transmission, including social distancing and mask wearing. Here we evaluated the spreading of viruses in open air using harmless Escherichia coli bacteriophages as a surrogate. Phages were sprayed towards Petri dishes seeded with bacteria at different lengths and angles. Median droplets size was 127 m, similar to those produced by sneeze. Our results showed that the transmission rate decreased exponentially with distance. The highest recorded transmission rate was 9x10E-6 PFU/plate when phages were sprayed from a 1 m distance. This suggests that the probability of transmission of a single phage at a 1 m distance is 1:100,000.