US company Moderna said Monday its COVID-19 vaccine was 94.5 percent effective in its trials, making it the second US company this week to report a highly effective vaccine, behind Pfizer.

The vaccine, called mRNA-1273, is currently in its third phase of the study, according to modernatx.com.

Usually vaccines are made out of inactive viruses, however, mRNA-1273 is made from messenger ribonucleic acid (mRNA), which is a genetic code that instructs cells on how to make the protein, which helps the body’s immune system make antibodies to combat the infection.

A total of 30,000 individuals participated in the study, in which 25,654 participants have received their second vaccination. 

The study's participants included all age groups, with the most participants belonging to the 45-to-64 age bracket followed by the 25-to-44 age bracket. The company ensured the inclusion of participants with a variety of medical conditions.