Dr. del Rio on the Reactogenicity of the COVID-19 Vaccines

Carlos del Rio, MD, executive associate dean, Emory School of Medicine and Grady Health System, distinguished professor, Department of Medicine, Division of Infectious Disease, Emory University School of Medicine, professor, Hubert Department of Global Health-Rollins School of Public Health, co-director, Emory Center for AIDS Research, co-primary investigator, Emory-CDC HIV Clinical Trials Unit and the Emory Vaccine and Treatment Evaluation Unit, Emory Vaccine Center, discusses the reactogenicity of the COVID-19 vaccines.

In vaccinology, toxicity is different from reactogenicity, says del Rio. Adverse effects are medically relevant events associated with vaccination, whereas reactogenicity is the immune system’s reaction to the vaccine, del Rio says.

The COVID-19 vaccines appear to have slightly higher reactogenicity compared with the influenza vaccine, but significantly less reactogenicity vs the shingles vaccine, says del Rio. Oftentimes, patients who receive the COVID-19 vaccine will have a sore arm and erythema near the injection site, del Rio says. Some individuals report myalgia, fatigue, headache, and fever following vaccination; however, these reactions typically resolve after about 2 days and are a result of immune system activation, del Rio explains. Notably, these reactions tend to be worse following the second dose of vaccine in patients who haven’t had COVID-19 and following the first dose of vaccine in patients who have had COVID-19, concludes del Rio.