One of the frequent arguments used by antivaxxers against the COVID vaccine is "It doesn't prevent transmission! Therefore vaccine creates deadlier variants!"
They actually got the science backwards, because they are mixing up bacteria and virus, but to explain all that, we have to explain how virus "evolves", and this can get a bit science-y.
As usual in most antivax myths, there is *some* truth in what they are saying, but they are misapplied. They think they can apply natural selection to virus. It doesn't really work that way.
Natural Selection And Breeding Stronger Bacteria
Darwin's theory of evolution has natural selection as a primary mechanism. In all species there are variations, and due to the natural environment, some of these variations will more suited for survival, while some will be less suited. In time, the more suited versions will proliferate, and the less suited versions will die out. Thus the species evolves.
This is happening with the new antibiotic-resistant bacteria and fungi. New variations are caused by natural mutations, and some may be more resistant to drugs designed to kill them, and those will survive, while others do not, thus resulting in newer strains that are more resistant to drugs.
So it may make sense for people who don't understand science to believe that vaccines, like drugs, are "selecting" virus that can resist the vaccines for proliferation. Except, virus are not bacteria or fungi. A virus doesn't multiply that way. And while vaccines *can* have a selection effect, NOT having a vaccine actually generates far more variants.
How Virus and Vaccine Works
A virus is not "alive" and cannot multiply by itself, unlike fungi or bacteria. A virus must infect a cell, and borrow its facilities to make copies of itself. Every once in a long while, the copying process goes wonky, creating variants. Most variants don't work, but every once in a long-while, they work better than the original.
Vaccine helps the body create the right antibodies to bind to the virus, preventing them from getting into your cells and copying themselves, which decreases the chance of creating mutations and variants. Weaker vaccines don't generate enough antibodies so some viruses will get through, but the reduced amount means you get weaker symptoms if any at all.
We have variants of COVID because we had almost a YEAR where we had no vaccine and infections ran rampant, giving the COVID viruses plenty of chances to multiply and mutate.
The way we can use a vaccine to stamp out a disease is to vaccinate as many people as fast as possible, so the virus does not infect enough people to create a viable mutation. We don't have that because we are playing catch-up with the virus, which had a ten-month start, and we can't wait for a "perfect" vaccine that can do both prevention AND stop transmission. The more we delay, the more variants we will see. The virus already mutated into several variants while we were creating the vaccine, so we are STILL playing catch-up.
Why Vaccine Does NOT Select Virus The Way You Think
I can already hear the antivaxxers howling: but COVID vaccines do not stop transmission!
Ah, but it does REDUCE transmission. You are less sick, if you do get sick at all, with COVID vaccine. The less sick you are, the less virus you can pass on to others. Add a mask or stay home, and you are unlikely to pass it on to anyone anyway.
After all, airbags and seatbelts don't prevent auto deaths. We still have them mandated, right?
But think about it... Bacteria and fungi live outside of human bodies independently. They live, die, and mutate there. Human body is just another part of their environment. If we use a lot of anti-bacterial stuff around us, it'd affect their environment, but they are mutating independent of us. We merely selected them.
Virus do NOT live outside human bodies (or animal bodies) for very long (hours, maybe days) and they can't multiply that way. They need a cell to survive and multiply, and mutate. Human body *is* their environment. By vaccinating, we minimize the chances of the virus gaining a foothold in our bodies, and thus, minimize their chance of mutating and surviving onto infecting someone else, esp. when combined with mask and social isolation.
But the antivaxxers are not completely mistaken. They're doing Chicken Little thinking every nightmare scenario will happen, and for vaccine, the nightmare scenario is ADE.
Antibody-dependent enhancement (ADE)
Your body's immune system, upon detecting a virus, will generate antibodies. But antibodies are specific to proteins that are on the virus exterior. Some antibodies can block these proteins which allow the virus to infiltrate cells (thus infect them). But sometimes, these antibodies end up doing the opposite: making it EASIER for the virus to infiltrate the cells. This is called ADE.
So how do we tell if the vaccine-caused antibodies are causing ADE instead of helping the immune system? You watch the body for how it reacts to infection by the virus. There are three possible outcomes.
1) Mild or no symptoms -- the body has fought off the virus, vaccine worked.
2) Breakthrough infection -- the body is overwhelmed, either the immune system was compromised or the vaccine didn't work
3) ADE -- the person got even SICKER than normal and developed symptoms faster than without the vaccine. The vaccine actually made things worse.
So far, no COVID vaccine ADE has been observed.
Booster Shots and Vaccine Resistance
Now the antivaxxers are probably screaming: "But you need booster shots! That proves vaccines didn't work!"
Actually, that proves that we have learned that you need booster shots to make sure we generate enough antibodies to minimize the virus in the body long enough for everyone to get vaccinated, thus leaving no unvaccinated groups that can carry the virus around, where it can mutate into new strains, and to reinfect others.
Also keep in mind that there are like 30 different COVID vaccines approved around the world. China and Russia have their own, all based on different technologies and methods. They work differently on different strains of COVID, and scientists are still tweaking the formulas for the booster shots. If COVID developed resistance to one type of vaccine, we can switch to a different type.
Where Do Variants Come From?
Generally speaking variants are probably generated within an immunocompromised who received various treatments to help him/her survive, yet suffered lingering symptoms for a long time, thus allowing the virus time to mutate, yet not cleared up. But it can also happen within a person who spent a LOT of time in the hospital suffering from COVID.
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