Virulence (noun)

The degree of severity or harmfulness of a disease or microorganism.

Origin:

Late 19th century: from french virulence, from latin virulentia, from virus 'poison'.

Examples:

1. The virulence of the virus was measured by the number of cases and fatalities it caused.
2. The virulence of the disease was particularly dangerous for elderly people and those with weakened immune systems.
3. The virulence of the bacteria was reduced by the new antibiotic, allowing patients to recover.
4. The virulence of the strain was determined to be higher than previously reported cases.
5. Scientists were studying the virulence of the virus in order to develop a vaccine.