The news media tell us to beware of possible reinfection with the SARS-CoV-2 virus, the virus that causes the disease called COVID-19. The news also warns us we may become infected even after vaccination. Should we be surprised?
If a microorganism, such as a virus, enters your body and reproduces, that is an infection, but not all infections lead to disease. The Human Microbiome Project at the National Institutes of Health reports that the average human hosts about ten-times as many bacteria as human cells. Most of the microorganisms infecting the human body are harmless and many are beneficial. Most of them do not cause disease.
When a person becomes immune to a disease, whether through vaccination or prior infection, it does not mean they get a magic force field that keeps the disease-causing agent away. The immune system responds to a disease-causing agent, in this case the SARS-CoV-2 virus, only after the agent enters and infects the body. Immunity allows the immune system to quickly identify and respond to an infection before it causes serious illness, but immunity cannot prevent the infection. In this regard, the SARS-CoV-2 virus and COVID-19 are the same as other infectious diseases.
So we should expect people immune to COVID-19 to still be susceptible to infection. We should also expect infections in immune individuals will not normally develop into serious disease. None of this should surprise anyone.
Of course, people with compromised immune systems may have little or no immunity even after vaccination or prior infection. This is the same as for other diseases. And for people with severe life-threatening conditions, even a minor infection might be a contributing factor leading to death. This, also, is the same as for other diseases. So none of this should surprise us, either.
Since my spouse and I have been vaccinated (and very-likely had prior infections), I am not concerned about becoming infected with SARS-CoV-2. If we were to become infected, we probably wouldn’t even notice the symptoms. But what about the risk of an immune, but infected, individual spreading the disease?
A large-scale Chinese study of almost ten-million individuals, published in Nature, found no evidence of asymptomatic individuals infected with SARS-CoV-2 spreading the infection to others. Other studies found that while the risk of spread is low from individuals who do not develop symptoms, infected individuals who will subsequently become ill with COVID-19 can begin to spread the infection two days before symptoms first appear.
These studies seem to indicate that, because an immune individual is unlikely to develop the disease even if infected, there is little risk of an immune individual spreading the infection to others.
To quote Florida Governor DeSantis, “[I]f you get a vaccine, the vaccines are effective; you’re immune. And so act immune.”
Posted 2021/04/22
A commenter adds, “If you’ve had the virus, you are immune. So act immune.“ 2021/05/29