Can the flu shot encourage the evolution of super-viruses/super-bugs?

Hey everyone!

I’m a staunch believer of the Flu Shot, and I try my best to get it every year. However, several of my friends firmly believe that the flu shot encourages the evolution of super-viruses, and will not get the shot purely on that hypothesis.

I believe they’re wrong, but I can’t prove my point, because they are too easily sucked in by the sensational hype caused by others who believe the flu shot can cause a multitude of diseases as side effects.

Now, if this were any other issue, I’d just let it slide, 'cause their opinions are their opinions, but because the flu is contaigious and deadly to those with compromised immune systems, I personally believe that if you are getting the flu shot, you are also getting it to save the community. I think that if you don’t get the shot, you are needlessly exposing others to the flu virus, should you become infected, and if that virus takes a life, then that death could have been completely preventable.


For those here who are for the flu shot:
Google could not come up with anything regarding “super viruses” and “flu shots”. There are thousands of articles talking about each topic on its own, but none (as far as my limited google-fu can uncover) together.
The SDMB considers “flu” too short a search term and won’t search properly :slight_smile:
I’d ideally like your opinion plus some sort of medical journal to back up the statement.

For those here who are against the flu shot:
Your task is to convince me that the flu shot is dangerous and spells the end of mankind.
Yes, you may spout the theory of “preserving the weak weakens the human race”.



Unlike an antibiotic, which kills the infection directly and which a pathogen CAN evolve a defense against, a vaccine merely makes the immune system better prepared to fight the infection using the same tools it would have anyway. Therefore, my WAG would be that, if anything, flu shots reduce the chance of super viruses evolving, the virus has less chance to evolve before being wiped out.

A vaccine is like giving mugs shots to the cops and the border patrol. Instead of having to wait until an infection is cooking inside your borders, identifing the offender and then building a smart bomb for it, the immune system has already done steps 1 & 2 and as soon as the first few invaders cross the border it’s ready to crank out an army.

‘weak’ is a subjective term, is Stephen Hawking ‘weak?’

Not anymore. (sorry, but that was too easy)

OK, I’ll do a little devil advocacy. Vaccines that greatly reduce the incidence of dread diseases consequently increase the number and proximity of naturally occurring breeding zones of potential novel super viruses. As the virus’ reproductive cycle is significantly faster than ours, this allows the virus to mutate new forms more quickly than we can mutate resistance.

That’s about it. But no, as has been stated, virus immunizations don’t breed superbugs in the way that improper use of antibiotics does.

I think there was an issue with China overusing antivirals as a prophylactic on animals though. It may have led to some resistance.

I just wanted to point out that improper use of antibiotics isn’t the only reason for antibiotic resistance. Improper use accelerates resistance, but antibiotic resistance is inevitable.

Agree with outlierrn

The OP specifies “flu shot.”

The shot is an inactivated vaccine. It contains a dead virus. It’s ment to incurage your body to develop antibodies that provide influenza protection.

I have a friend who is convinced you can get the flu from a flu shot. It’s true, you can get a shot and still get the flu. The dead virus in the shot might not be the same as the version that ends up infecting you. But you can’t get the flu from the shot. And a dead virus won’t mutate into a super virus.

I didn’t mean to imply that antiviral resistance was related to vaccines. I felt the question on vaccine resistance had been answered and since we were discussing influenza, I thought the antiviral resistance was an interesting development. outlierrn is correct.

It’s not uncommon to enjoy a brief spate of flu-like symptoms following the shot, hence the persistence of the meme

Technically, though, the flue shot does make the environment worse for certain types of flu viruses, namely those that it targets, which means that their reproductive success suffers; mutations of those viruses thus might cause an adaptive response that again raises reproduction rates (connoted with higher infection rates), and in that way, vaccination does ‘encourage evolution’, as does any environmental change that has implications on reproduction rates.

However, that doesn’t imply that the new virus strain is in any way more harmful than the old one was – that could theoretically be the case, of course, but I don’t see the probability for that significantly raised compared to a no-vaccination scenario, since evolution happens in that case, as well.

But it does mean that the flu shot will always remain a bit of a crapshoot, since, in the first place, those cooking up each year’s concoction will have to make a reasonable guess as to what viral strains will be the most common ones that year, and secondly, even those that are explicitly vaccinated against can develop in such a way as to render the vaccination ineffective faster than a new vaccine can be created and deployed.

So, in total, it’s perhaps questionable that the flu shot really does anything at all, but it probably won’t wipe us out any faster than any of our other efforts to that end. :wink:

How does a vaccine ‘encourage evolution’ when it inhibits reproduction. Cite?
[qoute]So, in total, it’s perhaps questionable that the flu shot really does anything at all, but it probably won’t wipe us out any faster than any of our other efforts to that end. :wink:

It’s not questionable at all. The flu shot is effective. cite

Inhibition of reproduction is the very definition of selective pressure.

OK, I see what is being said here. The available pool of hosts to the vaccinated virus is smaller so the non-vaccinated virus spreads faster. I accept that. I thought he was saying that the vaccinated virus would mutate faster.

No, there is obviously nothing in the vaccine that could influence mutation rates, but, by creating an environment less suited to the ‘base’ form of the virus, mutated versions of it – i.e. those sufficiently chemically different that the vaccination is no longer effective – are more likely to take hold.

And regarding the effectiveness of the flu shot, I probably should not have said it is questionable whether it does anything at all (but note that I said ‘probably questionable’), since it does effectively immunise against the selected strains it vaccinates against, however, whether or not this leads to a significant reduction in flu and flu-like illnesses regarding their severity is, to the best of my knowledge, somewhat harder to assess – still, getting the shot doesn’t hurt very much, and if we ever run into a superflu pandemic, we’ll probably be grateful for having the vaccination network in place.

Pedantic nitpick: viruses are neither alive nor dead; as they lack the innate ability for self-replication, or even the tools to build the necessary protein hardware for replication absent of the target host they lack the criteria to be considered “alive”. They are merely bits of free nucleic acids which are copied by the replication hardware of their host cells machinery.

Vaccines generally use a form of the virus for which the replication sequence has been altered (previously by mutation and selection, now more commonly by genetic modification), and (typically) the factors that generate adverse immune response have been altered or removed. This is not to say that a flu vaccine cannot be harmful (witness the Swine Flu debacle) but a flu shot will not cause the flu, nor will widespread immunization result in breeding some kind of hyper-resistant virus, as a person who has been immunized will not effectively replicate the virus and will cease to become an effective host (whereas someone who makes insufficient use of an antibiotic will become a reservoir while the bacteria mutates into an antibiotic strain).

Influenza virus strains tend to mutate quickly anyway owing to environmental sensitivity and replication error, which is why flu shots are needed every year to combat one or more widespread strains of the virus. A true ‘killer virus’ is unlikely to last that long, because it will kill too many hosts too quickly to maintain an effective resident population. The smallpox (Variola) virus was so effective because it resided with only a modest mortaility in the Eurasian populations it evolved in, but spread so rapidly and virulently among aboriginal populations that few members of the population remained to carry the virus on.

The value of modern flu inoculation to the overall population is somewhat questionable on broad terms, though. Certainly it is beneficial for those with compromised immune systems, but the selection of virus is based on guesswork, kind of like figuring out what fashion designers are going to put on runway models next year. It does little or nothing to protect older children and adults with healthy immune systems, and does nothing to prevent a “superflu” epidemic like the Spanish Flu of 1918 in the case of a particularly virulent and unanticipated influenza strain. Unlike the conquest of smallpox or poliomyelitis–which are relatively robust and well-evolved viruses that remain resident–eradicating “the flu” is an impossible goal for modern medicine, and will probably remain so until the development of adaptive immunization that recognizes the core protein structure of the Influenzavirus.


Do you mean that it *prevents few deaths *among older children and healthy adults? That I believe, because few in those groups will die from a case of the flu. But if you meant that it prevents few cases of the flu among those groups, that doesn’t match with what I’ve read at all. Older adults may benefit less from the vaccine since they mount a weaker immune response to it, but they have more at stake because when they do get the flu they are more likely to die. Cost-benefit studies often support the vaccination of working adults based on the value of their time away from work, which is why many employers pay for the shots.

What about someone like me that rarely, if ever, gets sick? The few times I got the shot, I did get sick with flu-like symptoms, so I swore it off and haven’t gotten the flu in over a decade.

I also recall getting a smallpox vaccination when I went into the Army. I ended up having a golfball-sized lump in my left armpit afterwards, and when I went to sick call for it, the Army doc told me it was a normal response and would go away. It did, but it freaked me out.

In the last 10 years, the only times I got sick was a few minor colds and a couple cases of strep.

Influenza viruses have two ways of changing their properties - genetic drift is the slow accumulation of the mutations, while genetic shift occurs when a virus exchanges a whole set of genes by those of a different influenza strain.

Since the influenza virus carries its hereditary information (RNA) on eight separate strands, new influenza strains develop when two different viruses infect the same cell, and produce offspring that contain a random mixture of the genomes of the two parental strains. In this way, animal influenza viruses, which by themselves are not very efficient at infecting humans, can acquire from human influenza viruses the ability to efficiently infect humans.

Such dual infections clearly is inhibited by the vaccine even if the vaccine only blocks one of the two viruses.