Transmission

Variants | 187

The epidemiological consequences of B.1.1.7, B.1.351, P.1 and those variants to come are currently not predictable. It is acknowledged that they probably all have a substantial transmission advantage (+ 25%?, + 50%?, + 70%?) (Davies 2020, Volz 2021, Leung 2021, Public Health England 20210126). Increased transmission will lead to more SARS-CoV-2 infections and more hospitalizations and might significantly increase the number of deaths over the coming months. Figure 16 depicts a simplified scenario showing the number of new deaths every six days from three different viral strains, assuming each strain started from 10.000 infections. It shows how a more infectious virus may lead to more deaths. There is now evidence that vaccines might have an impact on the transmissibility of SARS-CoV-2. Two studies show a decrease of viral load by 1.6x to 20x in individuals who were positive for SARS-CoV-2 (Petter 2021, LevineTiefenbrun 2021). It will take months to quantify the impact on local epidemics.

Figure 16. A more infectious virus could lead to many more deaths. Simplified, hypothetical scenario showing the number of new deaths every six days from three different virus strains, assuming each strain started from 10.000 infections. Source: Adam Kucharski, Associate Professor, London School of Hygiene and Tropical Medicine.