You can reduce their risk somewhat, but the elderly with pre-existing conditions are generally reliant on younger people without pre-existing conditions, so, at some point in time, they're going to be exposed to infected people.
The way to reduce their risk is to remove any unnecessary contact with people. I'm sure at some point, that'll be recommended, but the timing will be dependent on how widespread infection amongst the population.
You can take your pick on what multiplier to apply to the confirmed cases to get a number for total infected, and that number is, depending on whose stats you use, somewhere between 10 and 100. As testing becomes limited to hospitalised cases, that number will increase, but if you go with 50 for now, it implies there's 1100 x 50 people infected, or ~55,000.
As that number rises the chances of at risk groups having close contact with an infectious person clearly rises. At the moment, that risk is probably fairly low, but in a week, we could have 250k infected people, so it starts to become significant.
I think they'll start to move fully into the "delay" phase next week, and, as part of that, will start to recommend non-essential contact with at risk groups is kept to an absolute minimum.
The goverments action plan is thin on detail, but, if you've read similar docs before, the implications in it kind of support the above.
edit : The action plan, if anyone's arsed is
here
lol lol