t>
<dd><p>The date and time of sampling of individualID.2.</p></dd>

<dt>sampleDiff</dt>
<dd><p>The number of days between sampleDate.1 and sampleDate.2.</p></dd>

<dt>infectionDiff</dt>
<dd><p>The number of days between infectionDate.1 and infectionDate.2.</p></dd>

<dt>infectionDiffY</dt>
<dd><p>The number of years between infectionDate.1 and infectionDate.2.</p></dd>

<dt>timeCat</dt>
<dd><p>A categorical representation of infectionDiff: &lt;1y, 1-2y, 2-3y, 3-4y, 4-5y, &gt;5y.</p></dd>

<dt>Z1</dt>
<dd><