def create_events_model(areas, virus_states):
    """Create events for the model.

    Parameters
    ----------
    virus_states : list of strings
        List containing the names of all virus variants.

    Returns
    -------
    events: dict
        Dictionary that contains the event names as keys
        and dicitonaries that contain the event ids, and formulas
        as values.
    """

    events = {}
    for index1 in areas:
        for index2 in virus_states:
            keys = f"event_{index1}_{index2}"
            assignee = f"infectious_{index1}_vac0_{index2}"
            trigger_time_par = f"{index2}_{index1}_appears_time"
            trigger_quantity = f"{index2}_{index1}_appears_quantity"

            events[keys] = {
                "trigger_formula": f"geq(time, {trigger_time_par})",
                "assignee_id": assignee,
                "assign_formula": trigger_quantity,
            }
    return events