A third vaccine has been given Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) on February 27, 2021. The trial for the vaccine by Johnson & Johnson showed 72% efficacy at preventing all COVID-19 cases and 86% efficacy at preventing severe disease. While these numbers seem inferior to the two mRNA vaccines already licensed under similar EUA agreements, the Johnson & Johnson has one main advantage in that its storage requirements are similar to those of existing vaccines against diseases like measles or influenza: it can be refrigerated for up to three months.
The differences do not stop there, however. The Johnson & Johnson vaccine requires only one dose to confer immunity, unlike the two doses from the mRNA vaccines. The Johnson & Johnson vaccine is also based on an adenovirus vector delivery system. This means that DNA coding for the spike protein of the coronavirus that causes COVID-19 is embedded inside an inactive adenovirus. The adenovirus then enters our cells, and the DNA is integrated into the cell DNA and the process of creating the spike protein begins there.
As the report above states, this is a game changer for the global fight against the pandemic. Countries that cannot afford the technology for keeping mRNA vaccines cold enough for transportation and storage will be able to use the Johnson & Johnson vaccine. Countries that cannot afford to buy double the doses of vaccines that require two doses will also benefit from the once-and-done nature of this vaccine.