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 and an immune response. It is being rapidly prototyped and refined with community support 
 (<a href="#model_details">see below</a>). </p>
 
+<p><b>Please note that this is a stochastic model: for some simulation runs, you may see the immune system fail to respond. Users are encouraged to try the simulation multiple times.</b></p>
+
 <p>This multiscale simulator combines several modules:</p> 
    <ul>
        <li><strong>Tissue:</strong> Virus, cell debris, and chemokines diffuse within the extracellular space.