Our investigation into whining-based remedies became the first study to be halted by the IRB on the grounds that the treatment group was 'too annoying.'
When people are ill, they will often complain about the symptoms that they're suffering from. A common stereotype is that men will revert to infantile behavior when miserably sick. This can be annoying to the people around them, but they typically tolerate such behavior out of compassion. The joke in this comic is that Hairy spoke via a telehealth appointment to Ponytail, a medical professional who explicitly advised him to act out, since his condition has no effective medical treatment. He takes her advice to "act like you're the first person ever to have a cold" literally, stating it specifically when his companion asks about it. Given xkcd's humor in the past, this may be supposed to trick the cold virus into thinking that it has not had a lot of time to evolve to infect human cells effectively so that it does not infect Hairy's cells as effectively.
Alternatively, Hairy might be making up the doctor's advice to justify his behavior. This interpretation adds to the humor by suggesting that Hairy is pretending a medical professional told him to act like a baby to excuse his exaggerated complaints. The off-screen person's doubt highlights how absurd his claim is. This fits with XKCD's typical humor, which often mixes rational and absurd elements.
This comic was published during a "tripledemic" in the U.S., involving COVID-19, influenza, and respiratory syncytial virus (RSV, a frequent cause of common colds) infections, the latter of which do not have readily available effective treatments, other than to wait them out with plenty of rest and fluids (provided that symptoms do not require hospitalization). It expounds on the finding that "talking about troublesome events, including events with which one is dissatisfied, may ... result in improved physiological health." (Kowalski, R.M. (2002) "Whining, griping, and complaining: positivity in the negativity" Journal of Clinical Psychology 58(9):1023–35.)
The title text describes a similar study, but where the institutional review board (IRB) halted the study because the participants were too annoying. This is ironic since they were supposed to whine annoyingly for the sake of the experiment. IRBs are expected to review the ethics of a research project, with particular attention paid to the well-being of the subjects. Whining is not usually considered dangerous,[citation needed] but in this case it was presumably so intolerable to the Board (or perhaps the control group, who were presumably forbidden from whining while sick) that they had to put a stop to it.