• Risk group 1 includes micro-organisms that are not infectious agents.
• Risk group 2 includes infectious agents that can infect people but do not cause chronic disease, or the disease can be cured or effectively prevented.
• Risk groups 3 and 4 include the most dangerous infectious agents that can cause serious diseases.

Use the classification when assessing risk and choosing protective measures

The classification is a support for investigating and assessing risks. The higher the risk group an infectious agent belongs to, the more dangerous it is for the person using it. Therefore, as an employer, you must take stricter protective measures when your organisation uses infectious agents in the higher risk groups.

Classified infectious agents are listed in the provisions

As an employer, you are responsible for finding out which risk group the infectious agents you work with belong to. Many infectious agents are already classified and you will find them in the list in Appendix 7 of the Swedish Work Environment Authority's provisions and general guidelines (AFS 2023:10) on risks in the work environment.

If you do not find the micro-organism you intend to work with in the list, it does not necessarily mean that it belongs to risk group 1. Then you need to make a provisional classification yourself, according to the definition of infectious agents in risk groups 2–4 in the Swedish Work Environment Authority's provisions on infection risks.

If you are unsure which risk group your micro-organism belongs to, you should choose the higher risk group. You can change the classification later if it is found that the risks correspond to the lower risk group.

How to interpret the risk groups

Micro-organisms in risk group 1

Micro-organisms that do not cause disease in people belong to risk group 1. This is where moulds and micro-organisms that can only infect animals or plants end up. Normally, cell cultures from higher organisms are also placed in risk group 1. Micro-organisms in risk group 1 are not included in the list in Appendix 7 of the Swedish Work Environment Authority's provisions on risks in the work environment.

Infectious agents in risk group 2

Infectious agents that can cause infections that can be cured, prevented or that normally heal on their own. An example is common cold viruses.

Infectious agents in risk group 3

Infectious agents that can cause diseases with serious consequences and where the possibilities for cure or prevention are limited. The disease can also be highly infectious.

Examples of risk group 3 agents are HIV and Mycobacterium tuberculosis (TB).

Infectious agents in risk group 4

Infectious agents that can have very serious consequences, and where there is no or little possibility of cure or prevention, as well as a risk of epidemic spread or high infection. One example is the Ebola virus.

An infectious agent can belong to different risk groups

Two infectious agents belonging to the same risk group can have very different properties: while one spreads easily through the air, another can only be spread through blood.

Different variants of the same infectious agent can also belong to different risk groups, depending on the properties of that particular variant. An example is the intestinal bacterium Escherichia coli (E. coli), which is normally found in the intestinal flora of mammals. Many E. coli are not considered infectious agents but belong to risk group 1, for example those that are widely used in research. Some variants of E. coli can cause transient infections and are classified as risk group 2. Other variants are more harmful and are known as EHEC. They belong to risk group 3.