Use awk to split line into array and use that array's values in calling shell

I think that you can do what you want without awk:

cat "${smryfile}" | while IFS=: read first last varx
do
    echo "first='$first' last='$last' varx='$varx'"
    # do something
done

This produces:

first='Joe' last='Johnson' varx='25'
first='Sue' last='Miller' varx='27'

Note that this approach will work even if some names in the file include spaces.

Note also that the use of cat above is not necessary:

while IFS=: read first last varx
do
    echo "first='$first' last='$last' varx='$varx'"
    # do something
done <"${smryfile}"

A side benefit of removing cat, as per the above, is that any variables that you create in the loop will survive after the loop finishes.

This should work:

linearray=($(awk -F: '{$1=$1} 1' <<<"${smryline}"))
echo ${linearray[2]}
# output: 27

Explanation: awk -F: splits input on :. awk by default separates modified output with a space, so you can construct an bash array directly with the output from awk. Note modified output, hence the no-op call to $1=$1, else the data would just come out in the original form.

But given your example, why not extract the third column with awk -F: and loop the output:

awk -F: '{print $3}' "$smryfile" | while read varX; do
    echo $varX
done