Vaccination or engineered antibodies?

[Klpetrak]

I have no doubt that getting vaccinated is beneficial. However, the efficacy of vaccinations can be as low as 30%. One of the factors that is essential is the efficacy of an individual's immune system. It varies from person to person, and in some cases, mainly as related to age, it may not function at all, such as in neonates or at old age.

Vaccination initiates development of humoral immunity (the body produces antibodies against given antigen), with cell-mediated immunity involving memory T-lymphocytes. 

However, another way to obtain immunity is to transfer the actual antibodies between individuals. This opens a possibility of immunizing individuals with an inadequate immune system by introducing into their blood stream antigen / diseases-specific antibodies engineered and manufactured for that purpose.

Question: Is this option being pursued for flu vaccination? If not, why not?

[CharonY]

You have to understand that immunoglobins, just as other proteins, do not stick around forever. I.e. an injection of antibodies is not an immunization. Rather it allows to address an ongoing situation (which is done in immunoglobulin therapies). However, it does not protect for infections that have not happened yet, as vaccines do.

[Klpetrak]

I acknowledged the background you refer to by mentioning both the humoral and adaptive immunity. I did not feel it needed to be spelled out. 

Let’s not get bogged down in semantics. Vaccination / immunization generates an “alarm button” for the immune system to kick in when it recognizes a foreign structure / epitope. But often (day with flu vaccination), a defensive response is not initiated.  “There were 40,414 deaths in the U.S. during the third week of 2018, the most recent data available, and 4,064 were from pneumonia or influenza, according to the CDC data.” (sic) 

What I am suggesting is an alternative therapy for when the immune-system response is not adequate. It would not be a big issue to administer antibodies directly into the blood compartment to avoid a possible development of a life-threatening situation. It might be worth to engineer and manufacture such antibodies in parallel with developing flu vaccines. 

[CharonY]

It is a fundamentally different approach for an entirely different situation. In OP you clearly defined it as an alternative to vaccination and asked why it is not used as such. But again, it is for a different purpose. It does not, as you claim, provide immunity (at least not comparable to vaccinations). 

That being said immunoglobulin therapies are already in use e.g. for folks with immune disorders or some other forms of complications. There, prophylactic use can be indicated, but only for certain conditions (i.e. high risk of infections). These treatments are not targeted though (i.e. not need for engineered antibodies). Specifically for flu, there is experimental evidence in animal models that infusion with immunoglobulins (again, non-specific and non-engineered) may ameliorate symptoms of infected individuals. However, relatively high amounts are needed, the precise mechanisms are not quite clear.  Targeted approaches using engineered antibodies are likely to have a far lower efficacy as one would severely limit the target range.

Other than those therapies there are also more targeted uses of antibodies, such as as antivenom, but again, they are specific and usually responsive treatments. Another scenario is post-exposure prophylaxis. E.g. folks that got into contact with highly contagious diseases could be offered immunoglobulin injections.

If you are thinking of continuous transfer of IG as a form of immunization, it has several downsides. Long-term therapies have a range of side effects, which are acceptable if health of patient is at risk, but not if there is no indication. And also far more expensive than vaccines. 

So as a whole, it does serve a different niche than vaccines and is not really a viable alternative at this juncture.