Post-Vaccination Effects

What Can You Expect After Your Vaccine?


Reactions vary across the popula­tion. The over­whelming majority experi­ence no ill effects. The Vaccine Adverse Event Reporting System (VAERS) tracks out­comes. Over 285 million doses of COVID-19 vaccines were administered in the United States from December 14, 2020, through May 24, 2021. During this time, there were 4,863 VAERS reports of death (0.0017%) among people who received a COVID-19 vaccine.

During December 14–23, 2020, VAERS detected 21 cases of anaphylaxis after administra­tion of a reported 1,893,360 first doses of the Pfizer-BioNTech COVID-19 vaccine (11.1 cases per million doses); 71% of these occurred within 15 minutes of vaccina­tion. An immediate allergic reaction means a reaction within 4 hours of exposure including symptoms such as hives, swelling, or wheezing (respiratory distress). As a precau­tion, the administer­ing facility may request that you remain 15 minutes following injection for observation.

Non-serious fainting (syncope) and other events that may be related to anxiety like rapid breathing, low blood pressure, numbness, or tingling can happen after getting any vaccine. According to VAERS, there are about 8 fainting events for every 100,000 doses of the J&J/Janssen COVID-19 Vaccine. Women younger than 50 years old should especially be aware of the rare risk of blood clots with low platelets after vaccination. There are other COVID-19 vaccines available for which this risk has not been seen.

According to the Centers for Disease Control and Prevention (CDC), the COVID-19 vaccina­tion will help protect you from getting COVID-19. Following the second injection (first with J&J/Janssen) you may have some side effects that are normal signs that your body is building protection.

The European Medicines Agency (EMA) has advises against use of the AstraZeneca’s Vaxzevria COVID-19 vaccine in people with a history of capillary leak syndrome. This syndrome is a very rare but serious condition that causes fluid leakage from capillaries, resulting in swelling in the arms and legs, low blood pressure, thickening of the blood, and low blood levels of albumin.

Common Side Effects

On the arm where you got the shot:

  • Pain
  • Redness
  • Swelling

Throughout the rest of your body:

  • Tiredness
  • Headache
  • Muscle pain
  • Chills
  • Fever
  • Nausea

You may feel like resting in bed during the first few days. The weak­ness is a good thing, not some­thing to worry much over. Just don’t plan long excursions right away. It takes about two weeks from your final vaccine to build immunity. If you have a condi­tion or are taking medica­tions that weaken your immune system, you might NOT be fully protected even if you are fully vaccinated.

Just like everything else associated with this pandemic, people have opinions about which vaccine is best. The first thing you can expect to hear if you mention you have been vaccinated, is “Which type?” Depending upon your audience, this could lead to a lively debate. So you may choose not to walk that plank.

The ultimate goal is to vaccinate 8 billion people worldwide. There is faster population coverage with a single dose but the majority of vaccines require two doses. Vaccinations, with special passports will reinvigorate international travel.

Though hundreds of millions of vaccina­tions represent a good start. It is premature to announce a return to normal. The underlying message from health­care providers is that vaccina­tions, though a personal decision, are safe for the majority of those who qualify to receive them. The risk of infection without vaccina­tion is greater than the risk of adverse reaction from inoculation.

To support the writing of useful articles about immunology, ClinicalPosters sells human anatomy charts, scientific posters and other products online. Also shop for ClinicalPins that include more than lapel pins or leave an encourag­ing comment to keep the work going. Visible content is optimized for device size.

Login Register

Updated: Mar 24, 2023

Join Discussion