What’s taking so long? That’s the question asked by hundreds of thousands of people who have flocked to New Jersey’s COVID vaccine sign-up page to get inoculated. There are many answers, but the first is the most obvious: Demand far outstrips supply currently. The state has been allocated far fewer doses than the number of people who want them. More than a million have registered for the vaccine at covidvaccine.nj.gov, while about 600,000 vaccine doses have been received and 233,000 doses have been used. But a second reason for the slow rollout is that the COVID vaccines are different from any vaccines given before. The data-tracking required for each dose is daunting. Storage and preparation of the vaccine require special equipment and handling.