 The Covid-19 pandemic has led to the development of several vaccines, including Oxford, AstraZeneca AZ-1222, Pfizer-BioNTech BNT-162B2, Moderna mRNA-1273, and Armacron B8.12. These vaccines have been shown to provide varying degrees of protection against the virus, but it is unclear how long this protection will last. In order to better understand the duration of protection provided by these vaccines, researchers developed a mathematical model that incorporates data from England about the effectiveness of each vaccine. The model suggests that switching the fourth dose of the vaccine to one that matches the Armacron variant could lead to significantly more protection than continuing to use the ancestral vaccine. This article was authored by Alexandra B. Hopen, Patrick Duhann, Sean L. Wu, and others.