I don't think a fly in the ointment makes the ointment work better. But it's well established that certain irritant substances added to vaccines make those vaccines work much better. From Wikipedia:
[In] the early days of commercial vaccine manufacture ... significant variations in the effectiveness of different batches of the same vaccine were observed, [and were] correctly assumed to be due to contamination of the reaction vessels. However, it was soon found that more scrupulous attention to cleanliness actually seemed to reduce the effectiveness of the vaccines, and that the contaminants – "dirt" – actually enhanced the immune response.
A growing number of these immunity-enhancing substances, called adjuvants, have been identified, tested, and licensed for use in specific vaccines. They don't operate by providing the immune system with a "mug shot" of one or more distinguishing features of a pathogen, as the vaccine per se does. Instead, they soup up the immune response to whatever molecular mug shot happens to have accompanied the adjuvant on the joyride through the syringe and into the patient's arm. Adding an adjuvant to a vaccine is analogous to putting a cop (the immune system) on hyper alert, rendering said cop more inclined to ticket speeders (pathogens) even when they're only five or ten mph over the limit.
Adjuvants aren't licensed for use in a wholesale fashion, but rather are approved in specific combinations with specific vaccines. At the moment, no approved influenza vaccine/adjuvant combination is available in the United States.
But adding an adjuvant to the standard seasonal flu vaccine, or to a vaccine designed to ward off one of the pandemic strains we've encountered in recent years, soups up the immune response to the vaccine, as a multicenter, randomized clinical trial has shown. (The results are already reported online and will be published Sept. 15 in the print edition of the Journal of Infectious Disease) has shown. That's especially good news for older people, whose immune responses to vaccination tend to taper off with advancing age. More than 500 of the participating subjects were over age 65 - a hefty enough number to provide some confidence in the positive results among that group. Another 245 relative youngsters (i.e., under 65 years old) were also tested. The adjuvant helped them, too, although people in that age groups don't typically need much help.
A key player in that trial was Stanford vaccinologist Corry Dekker, MD, medical director of the Stanford-Lucile Packard Children's Hospital Vaccine Program, whose experience with adjuvants dates back to her days as a biotech executive from the late 1980s through the mid-1990s.
The bottom line is that pairing an adjuvant with the flu vaccine improves even the more-recalcitrant immune response of older people. In that demographic cohort, among whom an influenza infection can have serious and all too frequently life-threatening consequences, that dynamic duo would come in handy.