Risk matrix explanation

Published 2 December 2021

The Royal New Zealand College of General Practitioners risk matrix was created in 2020 and is an adaptation of one developed by occupational health physicians from the National Framework for the assessment of staff at work. 

The matrix was specifically designed to allow primary care doctors to assess the risks associated with COVID-19 for themselves, their colleagues, and their staff.  It was also intended to be used as the basis for discussions with patients who, although not in clinical roles, might find themselves exposed to COVID-19 in their workplaces.

How to use the matrix 

  • The first two columns relate to general practice staff with close clinical contact with symptomatic (red stream) and asymptomatic (green stream) patients
  • The last three columns are designed to start a discussion with patients in general. 

Specific advice for vaccinated staff working in a clinical area

Since vaccination appears to reduce morbidity and mortality in all groups, we have made the decision to give only general advice regarding workplace safety:

If you’re immunocompromised or in a pre-vaccination high risk category you should:

  • Ensure that you’re wearing appropriate PPE in whatever clinical situation you are in.
  • Ensure that your vaccination status is up to date.
  • Not work in a red stream area, particularly when there is a high prevalence of disease in the community.

Advice for clinical staff who’re pregnant

Unvaccinated pregnant people are at greater risk of complications if they become infected with COVID-19. However, the impact of vaccination and the use of appropriate PPE remains the same. 

Until further evidence is forthcoming, we recommend pregnant people should only work in the green stream seeing asymptomatic patients. This is assuming they’re fully vaccinated and wearing appropriate PPE.

Vaccination, morbidity, and mortality 

The matrix was first designed before COVID-19 vaccinations were developed.

As the pandemic has evolved, there has been a greater understanding of the nature of the disease and how to treat it. This alone has had an impact on mortality data along with the fact that an increasing number of infected patients will have been vaccinated, which has resulted in much milder and at time asymptomatic disease.

We know that vaccination significantly reduces morbidity and mortality, variously estimated at between a 10-and 20-times reduction in death.  However, we assume that the relative mortality figures will remain the same. The absolute figures will also depend on the prevalence of the disease in the community.

When using the risk assessment matrix, it's important to realise that several people will have more than one comorbidity. It is up to your clinical judgement to assess that additional risk. In addition, it may be necessary to consider others in an individual’s bubble and the risk that infection with COVID-19 would present to them.

As morbidity and mortality data becomes firmer, we will update this advice.

Increasing age is a known mortality risk factor and CDC* data below shows the relative risk of hospitalisation and death by age group as reported in September 2021. 

*All rates are relative to the 18- to 29-year-old age category. CDC website Sept 2021.

Although this data is useful it still leaves the question of what the absolute mortality figures are. We understand that at the beginning of the pandemic, first world mortality figures for unvaccinated patients aged 65 to 74 was about 10 percent. 

Table references 

  1. Rates are expressed as whole numbers, with values less than 10 rounded to the nearest integer, two-digit numbers rounded to nearest multiple of five, and numbers greater than 100 rounded to two significant digits.
  2. Includes all cases reported by state and territorial jurisdictions (through November 15, 2021, accessed on November 16, 2021). The denominators used to calculate rates were based on the 2019 Vintage populationexternal icon.
  3. Includes all hospitalizations reported through COVID-NET (from March 1, 2020 through November 6, 2021 accessed on November 16, 2021). Rates were standardized to the 2020 US standard COVID-NET catchment population.
  4. Includes all deaths in National Center for Health Statistics (NCHS) provisional death counts