COVID-19 Five Fast Facts

As COVID continues to impact our communities, we know you have questions about the disease and about vaccine safety and efficacy. UF Health experts are sharing five fast facts to help address your questions and concerns.

1. How the vaccine works:

Vaccines are coaches for our immune system — they teach the correct technique and how to win.

Our immune system uses several tools to fight infection, activating key cells that rally to our defense. The vaccine quickly teaches our body to recognize the part of the virus that causes COVID-19. Once that blueprint is made and antibodies to COVID-19 begin to be produced, the vaccine rapidly disintegrates. Learn more about how the mRNA vaccine works.  

Information on spike proteins:
Our immune system reacts to the mRNA in the vaccine in the muscle of the arm — the injection site — where it begins to make the spike proteins similar to those found on the surface of the virus. Our immune system recognizes that these proteins are new, and attaches to the cells displaying them. Immune cells then travel to lymph nodes near the injection site, where their ability to make antibodies and to become virus-killing cells is enhanced. The injection site and the local lymph nodes serve as the training arena for the immune system. The spike proteins do not circulate widely in the body, and people do not “shed” spike protein from their bodies. They do not damage the blood-brain barrier. The mRNA and the spike protein do not harm the DNA inside our cells.

2. Minimizing your risk of severe illness:

The vaccines — immune system coaches — use the best strategy for preventing serious illness.

Most people who are vaccinated do not contract COVID-19 — and if they do, the vast majority do not become seriously ill nor do they end up in the hospital. Those who are vaccinated yet hospitalized are typically immunocompromised due to other conditions; for example, some are organ transplant recipients. Getting vaccinated is your best strategy to avoid severe illness or dying.

Information on hospitalizations in unvaccinated compared with unvaccinated:
In an analysis from the CDC, hospitalizations in unvaccinated individuals were 28 times that seen in vaccinated individuals in Los Angeles County.

This graph shows age-adjusted rolling 7-day hospitalization rates which show an increase in the unvaccinated, more than partially or fully vaccinated individuals.

Our experience at UF Health is similar. The Department of Health dashboard shows that the vast majority of hospitalizations at UF Health that took place after vaccines became widely available were among the unvaccinated.

This graph shows the percentage of cases unvaccinated vs vaccinated at UF Health, with a large number of individuals being not vaccinated

3. How we know the vaccine is safe:

These vaccines have demonstrated a high degree of safety.

Over 221.5 million in the U.S. have now been vaccinated with the COVID-19 vaccines, with only rare serious adverse events. The vaccines have undergone rigorous safety reviews with no steps of the development process skipped. Real-world data is consistent with a high degree of safety. COVID-19 infections cause a much higher complication rate than seen with the COVID-19 vaccines.

In a comprehensive study published in a premier medical journal, The New England Journal of Medicine, a vaccination analysis was performed to compare the risks of vaccinating 888,000 people with two doses of the Pfizer vaccine with those with COVID-19 infection in 888,000 unvaccinated people.

Serious medical conditions (clots in the lung, heart and legs; kidney damage; heart problems such as abnormal heart rhythms; inflammation of the heart muscle; inflammation of the lining of the heart or bleeding in the brain) were all seen in higher frequency after an actual COVID-19 infection (shown on the graph in orange) than as a reaction to the vaccine.

This graph shows the risk difference of 100,000 persons who received the vaccine and those infected with SARS-CoV-2 in various illnesses

Why COVID vaccines stop the virus, not spread it:
The COVID-19 vaccines do not contain live virus and cannot cause an infection. COVID-19 vaccines help decrease spread of infection and do not enable or enhance the ability of the virus to enter cells. Scientists and clinicians have paid close attention to this while developing and evaluating COVID-19 vaccines. Unfortunately, there is misinformation about this topic circulating in some channels on social media. In fact, no vaccines in current use for any disease are thought to cause such enhancement, even those using inactivated, whole virus for other conditions. If COVID-19 vaccines caused such a phenomenon, more severe disease would have been seen in vaccinated individuals, which is not the case.

4. COVID-19 variants — why do they occur?

Over time, viruses mutate. These mutations are called variants. They are designated variants of concern when they cause more infections or higher severity of infection — alpha, beta, delta, etc. Higher viral replication and spread occurs in unvaccinated people. It is much more likely that a worse variant will emerge in unvaccinated populations. The higher the vaccination coverage in an area, the lower the mutation frequency and development of variants.

The best strategy to prevent new variants is to:

  • Vaccinate a high proportion of the population
  • Follow layered protective measures such as masking and improved ventilation to decrease transmission

Higher infections due to lack of vaccination enable development of variants:
COVID-19 vaccines coach our bodies to produce a trained immune response. Our bodies produce neutralizing antibodies, memory B cells and T cells to fight COVID-19. This leads to lower infections, decreased duration of illness, lower replication and decreased spread of infection. All variants of concern have emerged in settings of high infections. High community vaccination is a powerful way of preventing “leakiness” — development of new variants. This well-conducted study reveals that vaccination coverage rate was inversely correlated to the mutation frequency in many countries. In regions, mask wearing and other safety measures have also played an important role.

This graph shows the mutation frequency and the fully vaccinated rate of a variety of countries

5. What about a third dose of vaccine:

Some people have very compromised immune systems, and so do not mount a full protective response against the COVID-19 virus even after getting two doses of an mRNA vaccine or the J&J vaccine. For these people, getting an additional shot will “boost” their immune response so that they can be better protected. Further data will guide us on what the most effective COVID-19 vaccine series is in various age and risk status groups. This is the same policy we follow with all vaccines and is guided by the Advisory Committee on Immunization Practices, or ACIP, through the immunization schedule for adults and children.