Kali Kniel, Professor of Microbial Food Safety, University of Delaware, kniel@udel.edu
At this point in time, just short of 33 million Americans have been sick with COVID-19, and people continue to be sickened with the virus each day. Another number to consider is that more than 287 million Americans have received a vaccination to protect them from the COVID-19 disease. Many of those vaccinated are people who were previously sick and have recovered. Disease from COVID-19 can start an immune response that gives some protection from future disease, but it is important to note that this protection will vary depending on your individual immune system. That is why the Centers for Disease Control and Prevention (CDC) recommend that individuals who have had COVID-19 should still get vaccinated. The immune protection that a person gets with a full vaccination is superior to what a person might have after natural infection. Also, these vaccines have been shown to protect against the variations in the virus that causes COVID-19.
To understand this, let’s consider how our immune systems fight illness. Our immune systems’ response is a multi-pronged attack on an infection, using different types of white blood cells that fight the pathogen. Macrophages are white blood cells that specifically digest the germs and leave behind parts of these germs called antigens. The B-lymphocytes are defensive white blood cells and they produce antibodies to those antigens left behind by the macrophages. Then there are T-lymphocytes that are also defensive and attack infected cells, and these T-lymphocytes can have memory of these infections. A person’s immune system may take days or weeks to make these cells against the virus that causes COVID-19 and may only make a few cells that have lasting memory to the virus. This is where the vaccines are really effective. After the full vaccination the person has a great supply of memory T-lymphocytes.
Stopping the COVID-19 pandemic involves all of us. With recent guidance and data showing the incredible protection of these vaccines, after you are fully vaccinated you can unmask in many locations and visit with family and friends. Remember that fully vaccinated means 2 weeks-time after the second dose in a 2-dose mRNA vaccine or 2 weeks-time after the single dose of the J&J Janssen vaccine. So, to restate the question, should you get vaccinated even if you had COVID-19? The answer is absolutely!