Understanding personal risk using weekly COVID-19 data

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Oregon Health Authority (OHA) announced last week that some data about COVID-19 will now be updated weekly rather than daily.

Starting Sept. 14, weekly updates will include:

  • Newly reported and total COVID-19 cases
  • Newly reported and total COVID-19-associated deaths
  • Total current COVID-19-positive patients hospitalized
  • Percentage of statewide emergency department visits for COVID-19-like illness
  • Total newly reported COVID-19 tests and percent test positivity

Although many people relied on daily updates to assess their personal risk, weekly data still shows accurate and useful trends in how COVID-19 is spreading in Oregon. For example, if one week shows a higher case count or more hospitalizations than the previous week, it’s safe to assume that more COVID-19 is spreading.

Public health experts “have historically tracked other respiratory viruses, such as influenza, using weekly data,” said Dr. Melissa Sutton, OHA’s medical director of viral pathogens. “Our COVID-19 response has pivoted towards resilience — maintaining awareness of community transmission to inform individual-level risk decision making (for example, whether to wear a mask to the grocery store). Weekly data is absolutely sufficient to support this shift.”

Dr. Sutton recommends two key data points for people to understand COVID-19 community levels throughout Oregon: test positivity and wastewater monitoring, both of which will be updated every Wednesday.

Test positivity is the percentage of positive tests within the total number of tests performed. Doing this calculation allows experts to estimate how much virus is in the community over time.

Wastewater monitoring relies on the testing of water samples from wastewater treatment plants across the state. OHA works with Oregon State University to collect and test sewage samples, which can show us both transmission trends and estimate variants.

To assess your own personal risk, ask yourself these questions:

  • What threat does COVID-19 pose to me and my household or the people I often see in person?
  • How much COVID-19 is in my community?
  • How likely am I to contract COVID-19 from a particular event?
  • Do I have any personal events coming up that I would hate to miss because of a COVID-19 infection?

Here’s a step-by-step guide to using weekly COVID-19 data to assess your personal risk (scroll down for a simplified table):

Step 1: Weigh Your Risks

Think about three different buckets: personal risk, community risk and exposure risk.

Personal risk – What threat does COVID-19 pose to me and my household?

Think of personal risk as the foundation of your risk assessment. People at higher risk for severe illness from COVID-19 include adults 65 years and older and people with underlying health conditions or immunosuppression. Your personal risk may be high due to family or professional circumstances, such as caretaking responsibilities or concern for a loss of income due to illness. Those who have high personal risk may choose to use higher levels of caution, like masking indoors.

Community risk – How much COVID-19 is in my community?

Community risk refers to the levels of COVID-19 in each community. Reviewing test positivity and wastewater trends are good ways to understand how much COVID-19 is in your community. By using the Centers for Disease Control and Prevention’s (CDC)County Tracker tool, you can stay up to date with community level of infection and better understand what risk you’re facing when you venture out in your community.

Exposure risk – How likely am I to contract COVID-19 at a specific event?

Exposure risk refers to the chance of infection based on event specifics. If you’d like to attend an event outside your home, such as a concert, festival, wedding or party, consider the potential scenario. Think about crowd size and density, and whether it’s indoors or outdoors, to determine what level of risk you’ll encounter.

Step 2: Consider the Calendar

There are times when sickness is particularly unwelcome. Working within a two-week timeframe, note which upcoming life events, birthdays, vacations, or other activities you wouldn’t want to miss because of illness. When staying home would cause you to miss out on something special, temporarily increasing your personal safety measures is an easy way to increase your peace of mind.

Step 3: Adjust Your Behavior

Once you have a clear picture of your personal risk, adjust your behavior accordingly. If your overall risk is low, you may not need to make any changes. If your risk is high, it may be a good time to mask up, adjust your plans to be outdoors, and avoid large crowds. They key thing to remember is that your risk level is not constant. Regularly asking yourself these questions can keep you alert when you need to be, while letting you enjoy life more freely when you can.