The Army's COVID vaccine has shown success in primates and is now being tested on humans.

5 data from Washington state shows that people over 65 are 13 times more likely to be hospitalized and 15 times more likely to die from COVID-19 compared with those over 65 who received two doses of the Moderna or Pfizer vaccines or one dose of the Johnson & Johnson.

The Pfizer and Moderna vaccines use mRNA to build up immunity against the disease, and the Johnson & Johnson vaccine uses a harmless virus (not the one that causes COVID-19) to train the body's immune system to respond to COVID.

The US Army vaccine -- officially named the Spike Ferritin Nanoparticle (or SpFN) COVID-19 vaccine -- takes a third approach, using a harmless portion of the COVID-19 virus to spur the body's protection against COVID.

The Army's vaccine also has less restrictive storage and handling requirements than the Moderna and Pfizer vaccines, allowing it to be used in a wider variety of situations.

The vaccines from Moderna, Pfizer and Johnson & Johnson all target the specific virus -- SARS-CoV-2 -- that causes COVID-19.

To follow the progress of the Army vaccine trials, visit the SpFN COVID-19 Vaccine Tracker provided by the US Army Medical Research and Development Command.