Are helper functions in Meteor reactive?

Suppose I have the following code in my HTML file:

{{#if someVar}}

Now, if initially someVar returns false then the someTemplate Template is not created. Now, due to some event, the value returned by someVar is true will the template be rendered or not? Do I need to make someVar a ReactiveVar for this to work? Or should I use autorun? Which is the best and easiest method to do this? This can be achieved quite easily with 2-way binding in Angular.