By Daniel G. Graetzer, Ph.D.
Faculty Member, School of Health Sciences
Getting vaccinations against COVID-19 versus allowing natural immunity to develop has been a constant debate in the public arena. However, current evidence suggests that the best defense against future serious coronavirus infection is by vaccination, with an additional boost coming from natural immunity via prior exposure to the virus.
Vaccines work by training your immune system to handle viruses without making you sick. Vaccine-stimulated immunity involves the creation of specific antibodies that are able to recognize and “gum up” spike proteins on the outer virus shell, which inhibits its ability to enter body cells.
COVID-19 Infections and Hospitalization
According to MSN, one study assessed the risk of COVID-19 infection and hospitalization in four groups:
- Vaccinated with prior infection
- Vaccinated without prior infection
- Unvaccinated with prior infection
- Unvaccinated without prior infection
Ultimately, the study found that COVID-19 infection and hospitalization rates are currently highest among unvaccinated persons without prior infection. Reinfection rate for unvaccinated people who only have natural immunity currently appear to be twice as high as infection rate for the vaccinated.
Unvaccinated adults are at least 17 times more likely to be hospitalized from COVID-19 complications than vaccinated adults. At the same time, it is important to note that mutations can happen quickly; vaccines and the antibodies they produce provide just one defense against COVID-19.
Our intricate immune system has other ways to seek and destroy infected cells. For instance, T- cells (named because they become immunocompetent in the thymus gland), work to preserve memory and enhance immune response time during future exposures to a disease.
Related link: From Delta to Omicron: How Coronavirus Variants Behave
Infection Involves a Race Inside the Human Body
Infection can be viewed as a race inside the body. The Omicron variant of the coronavirus can replicate itself rapidly, and speed is the key in determining if virus multiplication continues to a serious level or if that virus replication is thwarted by the body’s immune system.
However, there is currently evidence of waning vaccine immunity in many persons, which has stimulated considerable research into booster shots. Some organizations have recommended that people get continual booster shots every few months. According to DeseretNews, however, the European Union warns that getting too many booster shots too soon may weaken your immune system.
Related link: The IHU Coronavirus Variant Is Not a Concern for Now
COVID-19 and the Body’s Immune System
If someone is not vaccinated and has never been previously exposed to any form of COVID-19, no customized antibodies or T-cells are available to protect lung tissue from invasion by the coronavirus. In an otherwise healthy immune system, it generally takes 7-10 days for the body to train undifferentiated T-cells to protect and kill infected cells. This time interval is much longer than the four days needed for killer T-cells to be summoned into battle following a vaccination.
Once an infection is overcome, immunity winds down. Some T-cells become memory T-cells, which can later respond to kill other cells and stimulate production of new antibodies when/if exposure to a similar variant occurs.
B-cells, which develop from stem cells in bone marrow, also assist in antibody production. The more a coronavirus replicates and spreads, the larger the response from killer T-cells.
However, T-cells need to be curtailed from killing other cells without restraint, so regulatory T- cells are normally effective at reining in this activity. If the “off switch” is not thrown soon enough, huge numbers of killer T-cells can potentially flood an infected area with very damaging cytokines, potentially causing a “cytokine storm.”
T-cells, B-cells, and natural killer cells are all white blood cells that originate in the bone marrow with T cells coming in two basic types: killers and messengers. Viruses that have migrated inside cells are hidden from antibodies. Killer T-cells then release toxic cytokines to stop virus replication.
Recent research has indicated that natural defenses in the nasal passages of children may help defeat the coronavirus before it can enter the body and excessively replicate itself. By contrast, this type of innate response appears delayed in some older adults whose immune systems, in an effort to “catch up” in the race between viral replication within cells vs. virus destruction by immune defenses, may then cause excessive inflammation and ultimately more severe damage. Aging often results in less production of new T-cells that are ready to learn, recognize and defeat new health threats.
For now, COVID-19 vaccinations provide the safest protection against COVID-19 infection, hospitalization, and death, with some additional protection created from infection by previous variants. But this disease remains unpredictable in some respects. For instance, we don’t know if there will be future coronavirus mutations and how much protection will be provided by currently available vaccines, boosters, and prior infection by earlier variants.
But there is still hope. Researchers are working on a universal COVID-19 vaccine, so stay tuned!