Disease and Viral Outbreak Guidelines


This page contains information regarding disease or viral outbreaks, such as potential epidemics, pandemics, influenza cases worldwide, as well as general flu prevention and preparedness.

For updated information about the ongoing COVID-19 pandemic, please visit this Student Health Services page for detailed information.  

General Flu Safety Precautions (from the California Department of Public Health)

Follow these flu prevention tips:

  • Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
  • Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
  • Try to avoid close contact with sick people.
  • If you get sick with flu, it is recommended that you stay home from work or school and limit contact with others to keep from infecting them. Avoid touching your eyes, nose or mouth. Germs spread this way.

Seasonal Influenza

Seasonal influenza typically results from one or more subtypes of the Influenza A virus (H1N1, H1N2 or H3N2) or from the Influenza B virus. Vaccination and previous exposure to these viruses results in varying levels of immunity and tends to limit the most serious effects of seasonal influenza to the elderly, the very young and those with pre-existing health conditions.

WHO Pandemic Threat Level

The World Health Organization (WHO) defines a pandemic as follows: "A disease epidemic occurs when there are more cases of that disease than normal. A pandemic is a worldwide epidemic of a disease." Typically, the term pandemic is used in reference to an influenza pandemic due to the threat of such pandemics, but pandemics can occur in other disease types as well.

WHO classifies the pandemic influenza threat into six phases, as follows:

  • Phase 1 - animal influenza cases which do not present a threat to humans
  • Phase 2 - animal influenza cases which may present a threat to humans
  • Phase 3 - small clusters of animal transmission to humans
  • Phase 4 - verified cases of human to human transmission
  • Phase 5 - human to human transmission in 2 or more countries in one region (pandemic imminent)
  • Phase 6 - pandemic - community-level outbreaks in more than one region

2009 Novel H1N1 Pandemic

In May 2009, a novel strain of the H1N1 subtype, often referred to as "swine flu", appeared. Initially, cases were limited to animal-to-human transmission, but quickly changed to widespread human-to-human transmission and was classified as a pandemic by the WHO in June 2009. This strain appears to be more easily spread than other H1N1 strains and has resulted in numerous human cases outside of the traditional flu seasons in all parts of the world. The novel H1N1 strain also appears to affect individuals under the age of 25 more severely than seasonal influenza does, and is also of particular concern to pregnant women and those with pre-existing health conditions.

UC Santa Cruz saw over 100 cases of H1N1 flu on campus in 2009 and 2010.

H5N1 is another subtype of the Influenza A virus which primarily infects birds, but which can also spread to humans. This virus is commonly referred to as "avian influenza" or "bird flu".