77% of the Spanish population, have had at least one dose of the vaccine against SARS-CoV-2, while the 70% is fully vaccinated. However, the number of positive cases have not disappeared and more and more immunised people are testing positive in diagnostic tests. But, can someone who has been vaccinated test positive for COVID-19, and can they also be contagious?
Vaccination is a simple, safe and effective way to protect against COVID-19. After vaccination, our immune system produces T-lymphocytes and antibodies, just as it does when we are infected. However, vaccination almost never causes illness and train our immune system for future infections.
Once we receive the full course of a vaccine, as elblogdepills summarises in the following illustration, the maximum levels of antibodies are reached days after the second dose and more and more countries are requiring these “extra” days to enter their country.
In the recent SIREN (SARS-CoV-2 Immunity and Reinfection Evaluation) study carried out by the British public health system, the National Health Service (NHS), it was concluded that the antibodies created by the vaccine can largely prevent us from becoming infected, but, the possibility of infection still exists. However, once we have received the full course of the vaccine, our immune system protects us from suffering the severe symptoms that the disease would cause. Why?
If we become infected after vaccination, since we have a trained immune system, the body eliminates the virus before it causes serious damage to the body, and this is why, in vaccinated people, the symptoms are milder.
In short, the vaccine can prevent infection, and if you get infected, it can protect against severe complications such as hospitalizations and/or death. But while our immune system is trying to kill the infection, can we still infect others? Yes, people who contract the disease, even if they are vaccinated, can infect others. During the period when the virus is still multiplying in our bodies, our ability to spread the virus will determine our ability to infect others.
Nor should we forget that new variants and even those vaccinated with mild symptoms can be a source of virus spread. Therefore, the early detection of COVID-19 positive cases, in which antigen tests (BH Ag Test) are essential, and, as @davidcallejo10 tells us, following the DIMAMA (Physical Distance, Hand Washing and Mask) are the key to prevent the widespread of the virus.
The vaccine prevents severe symptomatology in sick people, but does not prevent transmission of the virus. Therefore, the early detection of infection and individual responsibility are the best allies of vaccines.