Francisco R. Velázquez, M.D.: If you had COVID-19, should you still get the vaccine?

This is a common question particularly when almost 9% of Spokane County has had the disease, confirmed by laboratory tests. The short answer is yes, you should. Let me explain the rationale behind this answer.

Several people have asked me why they shouldn’t just wait to get the disease since over 90% of the cases recover without any long-term effects, and there is a large proportion that have either mild symptoms or no symptoms at all. That is true, but there is also a percentage of people who do get very sick. The reality is that in Spokane County, over 2,000 cases ended up in the hospital, many in the ICU. And more concerning, we have recorded over 650 fatalities from this disease. The question I ask is would you take that chance? Would you take the chance of infecting someone else who might get sick? For me, the answer is no. The benefit of the vaccine vastly outweighs the potential risks of the disease.

To best answer the general question posed in the title, we need to briefly review the basic elements of the immune response to the virus and how it interacts with our immune system. The immune system remembers a past infection in several ways. One involves the B Lymphocytes (B cells) that produce the antibodies, proteins that bind to certain molecules on foreign objects (called antigens) like bacteria, or viruses that enter the body. This tells the body that the object is foreign and marks it for destruction and removal. Some B Cells will continue to produce antibodies after the infection while others will remain dormant (memory B cells) until the specific antigen is identified again. Research suggests that antibodies in people infected with the COVID-19 virus decline rapidly over two to three months but may be present for much longer.

In addition, studies demonstrate that up to 9% of the people infected will not have detectable antibodies in circulation. At this point it is unclear whether past infection will protect from reinfection or for how long after disease. In addition, we know the current vaccines induce a much higher level of antibody production, and these antibodies will cross react with other strains of the virus, thus proving evidence that vaccines may be more effective against the emerging variants. Data also suggest that some previously infected people will generate a much stronger antibody response after immunization than those without prior disease. Coincidentally, recently released data suggest memory B cells generated by infection will produce a much more potent response, which may also protect against variants after immunization. This data will come into play when we evaluate the potential need for booster shots.

Another participant in the immune response is the T lymphocytes or T cells. These are one of the major components of the adaptive or acquired immune system. Their roles include directly killing infected host cells, activating other immune cells, and producing specific proteins called cytokines. Cytokines are involved in the regulation and modulation of many cells involved in the inflammatory process. There are several types of T cells; the three most critical within this context are helper, cytotoxic and regulatory. These are commonly referred to as CD4+ (helper) or CD8+ (cytotoxic or killer) due to cell surface receptors. When an infected cell is recognized, the CD8+ cells destroy it by producing specific molecules. In turn, the CD4+ cells generate cytokines that signal other immune cells. Regulatory cells shut off the immune response to prevent unnecessary damage. Typically, the killer T cells reach the highest concentration during infection, but a small number may persist for years to decrease the reaction time for the next response. However, with COVID-19 patients, reports show the expected increase of T cells does not occur. In fact, the overall T cell count in blood is lower in many COVID-19 patients, and this reduction seems to correlate with disease severity. Sicker patients have lower counts; the reason is not clear at this point. T cells, specifically killer (CD8+) cells, are critical in the response and further evidence suggest they can recognize virtually all mutations. Thus, they are not hindered by at least some of the variants of concern. Research conducted on the two m-RNA vaccines demonstrated a robust T cell response, including the generation of T cells that specifically recognized the key variants of concern.

So, why should you get vaccinated even though you had COVID-19? According to the data we have available, of those who contract the infection, not everyone will develop an appropriate antibody response to protect them from future infection. In fact, the virus seems to cause a diminished T cell response. However, when people who had disease get immunized, they actually experience an enhanced response. In addition, the vaccines offer a protection against the variants that is much greater than from infection alone. All in all, if you had the disease, the vaccine will boost your immune system and provide you with a sense of security knowing you are protected.

Francisco R. Velázquez, M.D., S.M., is the interim health officer for Spokane Regional Health District.