When taking the Johnson & Johnson vaccine into consideration, it modifies an existing adenovirus, which usually causes common colds, with COVID-19’s spike protein, also known as the piece of the virus that latches onto our cells. The resulting adenovirus does not have the ability to reproduce in our bodies. This means that the vaccine cannot cause us to have COVID-19 or any other illnesses for that matter.
The modified adenovirus is pulled inside your cells and it travels to the nucleus of the cell. The adenovirus then inserts its DNA into the nucleus, the spike protein gene is read by the cell and is then copied into messenger RNA, or mRNA. Then, your cells begin to create the spike proteins, which are then recognised by your immune system, causing your body to produce antibodies to the perceived threat.
In case you didn’t quite follow that: it’s like a meet and greet between your immune system and COVID-19. By means of the vaccine, your body is made aware of how to produce antibodies for the illness, without having to experience all of the side effects that come with a real COVID-19 virus. The immune system remembers how to respond to the spike protein and if you come into contact with it in the future, your body will be able to fight it more efficiently.
That being said, it’s not exactly crystal clear how long the protection lasts or whether or not the vaccine aptly prevents person-to-person transmission of the virus, according to the FDA.