A Field Trip Fit Only For an Infectious Disease Nerd: A Flu Vaccine Plant

A couple of weeks ago, I had the pleasure of taking the ultimate nerd field trip. Where did I go?  To an influenza vaccine plant, naturally. This was no ordinary vaccine plant I got to see though, it belongs to Protein Sciences Corporation: the sole supplier of the only recombinant influenza vaccine, Flublok

I am someone who has been a critic of the ordinary flu vaccine for myriad reasons, chief among them are its poor efficacy and the cumbersome and snail-like manufacturing process. These two deficiencies will spell doom in the face of a flu pandemic when speed, adaptability, and high efficacy could crucially alter the trajectory of the viral spread. Recombinant vaccines, not reliant on chicken eggs, fulfill these criteria and, as such, they are the vaccines of the future (not just for flu, but possibly for many other infections). 

Currently, the FDA has approved a 3-strain version of Flublok for use in adults. Many people, however, believe Flublok to be the vaccine of choice for those with severe egg allergies -- which it is -- and fail to realize there are more reasons to possibly prefer this vaccine over other options.

There is a growing body of data, for example, showing that this vaccine, in a yet-to-be-approved 4-strain form, provides superior protection when compared to the ordinary vaccine. "So what?" you might think, "4 is better than 3 and there is no 4 strain Flublok yet." Indeed, that is what I thought until I studied this vaccine in more detail and realized that its superior perfomance was due to something that nullifies the above argument.

Its advantage is its ability to ward off the tricky-to-grow H3N2 A strain included in both 3 and 4 strain vaccines; not the extra B that is included in quadrivalent vaccines. Remember, since Flublok is a recombinant vaccine there's no growing in chicken eggs and, consequently, no mutations that occur during growth creating a difference between what strain was used to construct the vaccine and what ultimately hatches at the end (such differences are likely a cause of diminished protection seen with the routine vaccine). Additionally, Flublok contains 3 times the amount of antigen per strain than the ordinary vaccine which also may play a role in its potency as does its ability to stimulate antibodies that are more broadly protective (against the hemagglutinin stalk in addition to the globular head). Overall, this approach has very high biological plausibility and I anticipate clinical studies will soon be published that definitively confirm these findings.

Flu is the big beast, the infectious disease I fear most. This flu season I might try the vaccine of the future.