Ubel PA, Comerford DA & Johnson E (2015) Healthcare.gov 3.0 - Behavioral economics and insurance exchanges. New England Journal of Medicine, 372 (8), pp. 695-698. https://doi.org/10.1056/NEJMp1414771
First paragraph: In October 2013, the Affordable Care Act introduced a new insurance market - state and federal exchanges where people can purchase health insurance for themselves or their families. Although the rollout of the exchanges was disastrous, around-the-clock efforts fixed many of the biggest technical problems, and nearly 7 million people purchased insurance in the new market. The second round of enrollment exposed some new problems with the exchange websites - for example, Colorado's website had difficulty determining whether people were eligible for tax credits - but these problems paled in comparison with those encountered when the exchanges were first rolled out. In short, we have a largely glitch-free system of health insurance exchanges that present millions of people with a robust set of health insurance choices.
New England Journal of Medicine: Volume 372, Issue 8