Four of the 7 types of human Coronavirus only cause mild respiratory infections

There are seven strains of human coronaviruses: Wikipedia

Causes Respiratory infection
1) Human coronavirus 229E (HCoV-229E)
2) Human coronavirus OC43 (HCoV-OC43)
3) Human coronavirus NL63 (HCoV-NL63, New Haven coronavirus)
4) Human coronavirus HKU1
    Note: Rhinovirus makes 10% to 40% of ”common colds”
    Approximately 200 types of virus result in the “common cold”
Causes Serious infection
5) Severe acute respiratory syndrome-related coronavirus (SARS-CoV)
6) Middle East respiratory syndrome-related coronavirus (MERS-CoV),
7) Novel coronavirus (2019-nCoV) = Wuhan coronavirus.

• “Coronaviruses can cause pneumonia, either direct viral pneumonia or a secondary bacterial pneumonia and they can also cause bronchitis, either direct viral bronchitis or a secondary bacterial bronchitis”

Note: There are lots of Viruses
380 trillion viruses in each human (10**14)
million trillion trillion viruses on the planet (10**31)

Speculation that 2019-nCoV could become the 5th endemic coronavirus (Widespread, seasonal)
Experts envision two scenarios if the new coronavirus isn’t contained Feb 4 2020

• "OC43 and 229E are more prevalent than other endemic human coronaviruses, especially in children and the elderly. Together, the four are responsible for an estimated one-quarter of all colds"