IT’S STILL unclear how well the Affordable Care Act will function. But on Wednesday, the law started working for a good chunk of those it was designed to help. The formerly uninsured who signed up for health-care plans under its provisions are now able to use their new coverage. As The Post’s Lena H. Sun and Amy Goldstein reported Sunday, those people include Illinois financial consultant Adam Peterson, 50, who will be able to get long-needed gallbladder surgery, and Tennessee student Emily Wright, 28, who can have a specialist look at a suspicious mole.

Judging by the enrollment numbers the Obama administration released over the weekend, the stories of deferred care finally obtained will be repeated over and over in the coming months, and many others without pressing needs will have the peace of mind that comes with protection against financial ruin from major illnesses and injuries. After a December enrollment spike, more than 1 million people have chosen plans through, the once-dysfunctional federal Web site. About the same number have probably signed up on state-based marketplaces. And about 4 million poor Americans have enrolled in Medicaid, which is in the process of expanding.

Yet the painful truth is that, if it hadn’t been for the incompetent rollout of and resistance from Republican politicians, more people would have new coverage. Two million enrollments in private plans is behind the goal of 3.3 million the Obama administration set for Jan. 1. Though many more probably will enroll as the final deadline for 2014 coverage approaches,’s disastrous introduction both foiled people from signing up early and dissuaded others from trying at all. That’s on President Obama’s shoulders. On Republicans’ is their continuing refusal to expand Medicaid without reasonable cause in many of the states they control, leaving millions of poor Americans without access to affordable coverage.

Consequently, the overriding task is to increase enrollment, particularly among target populations. That’s not only for the well-being of those who will get coverage but also because insurers need enough healthy people paying into the system to offset the costs of the sick. They based their 2014 offerings and premiums on estimates of what that balance would look like; if the estimates fail to match reality, financing the system could be a challenge. Halfway through the open-enrollment period, it’s past time for a sustained publicity blitz.

Outreach can’t end once people leave As more people enter the health-care system, there will be confusion. Some might make more frequent (and expensive) visits to the emergency room rather than get a primary-care doctor. Still others might think they have coverage when they do not, perhaps because they failed to pay their insurers or because a computer bug mangled their applications . And those who have to pay more for insurance or take a cut in benefits — not everyone will win in a coverage expansion of this size — will be angry.

Through all this, observers should keep calm. The Obama administration’s success at tackling many of the tasks ahead won’t be clear for months, once the open-enrollment period ends and more numbers start coming in.