California health officials Friday reported a second case of “unexplained” coronavirus (COVID-19). The infected person is an elderly female who does not have a travel history and no known contact with an infected person. She does have other chronic health conditions.

The first California case was a woman in Solano County, located between San Francisco and Sacramento, who fell ill after no known contact.

In Oregon, the first case of the virus was also announced Friday. The patient’s identity was not disclosed but according to Oregon Health Authority Director Patrick Allen, there was no known travel exposure. These new infections may indicate a change in thinking by health officials about how the COVID-19 virus moves from person to person.

The Centers for Disease Control and Prevention outlines five steps in the chain of infection:

  1. First is the “reservoir” where the infectious agent lives, grows and multiplies. This can be an animal, human, or a nonliving host, such as fecal material in the soil or water. Bats or animals sold for consumption in China’s Hubei district are the likely original reservoirs for COVID-19.
  2. Second is the “portal of exit," a path by which a pathogen leaves its host. The mouth, nose, a cut in the skin or a puncture in the skin are common portals of exit.
  3. Next are the “modes of transmission” that can be direct as in droplets from a sneeze, or indirect as when a third entity such as the atmosphere or an infected surface (like a smartphone or handrail) acts as a station for the germ to be picked up by someone who comes in contact with it.
  4. Fourth is the “portal of entry," the path by which a pathogen enters a new host.
  5. People with immunity or a natural resistance necessitate the fifth step and that is the “susceptibility of a host." This determines if the new host will become ill or not, which depends on genetic or other nonspecific factors in an individual’s ability to resist infection. The host is now a reservoir and the cycle will continue exponentially unless there is an intervention with a quarantine or vaccination.

The World Health Organization has raised its risk alert to the highest level over the coronavirus outbreak The World Health Organization has raised its risk alert to the highest level over the coronavirus outbreak Photo: AFP / NOEL CELIS

The term “community transmission” simply means that the source of infection is unknown but is lurking somewhere.

Dr. Sara Cody, Health Officer for Santa Clara County and Director of the County of Santa Clara Public Health Department, said of the latest case in her state, “This new case indicates that there is evidence of community transmission, but the extent is still not clear. This case does signal to us that it's now time to shift how we respond to the novel coronavirus. What we know now is that the virus is here, present at some level, but we still don't know to what degree.”

While the chances of widespread transmission remain low because of measures already in place like travel bans and quarantines, these new cases suggest that COVID-19 can bypass them. This opens the door to additional health fears caused by the coronavirus throughout the U.S. and other countries.