From claims that masks cause carbon dioxide poisoning (they do not) to suggestions that Covid-19 vaccines can alter your DNA (they cannot), the internet continues to be awash with conspiracy theories centred around the Covid-19 pandemic.
The newest of these is that vaccines against Covid-19 can actually give a person Covid-19. This is simply impossible for all Covid-19 vaccines of all types, but where might this claim have come from? The answer might lie in a bit of vaccine history.
There are some vaccines which work by giving a person a small dose of a dead, or weakened live virus for the immune system to get its teeth into with no risk of actually making the person sick. The dead viruses are well, dead meaning they can’t replicate inside of a human and cause illness, but can still spark an immune response.
The live vaccines are modified to weaken them, meaning that they can’t cause serious disease in people with healthy immune systems, but they are technically alive. Examples of these live, weakened vaccines are those against measles, mumps and rubella and chickenpox.
Vaccines of both types exist for polio, a virus which can cause a devastating disease that affects the brain and central nervous system, which can be fatal.
Both types are very effective and safe in people with normal immune systems, but live viruses are not recommended for people who are severely immunocompromised, for example children on active treatment for many types of cancer. In the United States, only the fully inactivated type is currently used and has been since 2000, but in other parts of the world, the live, weakened virus is still used.
Most people in their mid-twenties and older around the world will have been given the live weakened vaccine by mouth when young, sometimes dripped onto a sugar cube or candy to make the experience a little more pleasant.
So if that’s you and you’re now worried that the Covid-19 vaccines will give you Covid-19, you’ve already been given at least one actual ‘”live” vaccine and if you’re reading this, you survived.
Onto the Covid-19 vaccines themselves.
All of the vaccines against Covid-19 currently approved for, or being considered for use in the United States, contain genetic code to produce a tiny fragment of the SARS-CoV2 coronavirus called the Spike protein, but not any of the other numerous proteins that make up the whole viral particle.
So it is completely impossible for this spike protein alone to give you Covid-19. It’s like four tires on the starting grid of a racetrack, you know that they are car parts, but there’s no way someone can drive them around without the rest of it.
The Spike protein on its own is simply a beacon – it warns the immune system so that if it should encounter Spike proteins again in the future, attached to the coronavirus, the immune system can quickly work to neutralise the threat.
The vaccines by Moderna or Pfizer/BioNTech use a single-stranded bit of code called mRNA to tell human cells to make the Spike protein. The AstraZeneca and Johnson & Johnson vaccines use double-stranded DNA carried by a type of virus called an adenovirus, which ultimately gets turned into mRNA encoding the Spike protein too.
In summary, your Covid-19 vaccine absolutely cannot give you Covid-19 because its missing the instructions for almost all parts of the virus. It is important to note that this is very different from the question of “can people vaccinated against Covid-19 get infected with the SARS-CoV2 coronavirus?” where the answer is yes.
Whether or not a person is infected and whether they have symptoms depends on multiple different variables, including when the person was vaccinated, their age and whether they have any other health conditions that might mean that they get milder protection from the vaccines.
Some people have reported testing positive for Covid-19 shortly after receiving their vaccines and this is not unexpected and will continue to happen.
Vaccines provide minimal protection until at least two weeks after the first shot (and maximal protection around two weeks after the second shot with the two-shot vaccines) and it is likely that people who test positive soon after the vaccine either unknowingly had Covid-19 beforehand, or were infected in that two week window. They will not have been given Covid-19 from the vaccine.—Forbes
Victoria Foster is a postdoctoral research scientist focusing on childhood cancers and new, targeted cancer therapies.