Nu U Inc. did not recommend the option, but there was a certain small segment of the population that liked to leave the actual mutation up to chance. As a result of this, they offered what they called a Monster Lottery in which you would go in, pay, and spin a big wheel filled with a number for each strain of the Flu.
Once it landed, you were not told which strain it was, only given a chance for a refund. Those who wanted to continue were injected immediately and taken to an appropriate part of the facility to ease transformation.
Some were not happy with the results, but they had signed the consent form so they had to live with their new bodies. Most were just happy to be past the trauma of the flu and went on to live happy new lives.
In one day walks....