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. 2021 Nov 26;39(48):7066-7073.
doi: 10.1016/j.vaccine.2021.10.019. Epub 2021 Oct 16.

Reactogenicity within 2 weeks after mRNA COVID-19 vaccines: Findings from the CDC v-safe surveillance system

Johanna Chapin-Bardales  1 , Tanya Myers  1 , Julianne Gee  2 , David K Shay  1 , Paige Marquez  1 , James Baggs  1 , Bicheng Zhang  1 , Charles Licata  1 , Tom T Shimabukuro  1
Affiliations

Reactogenicity within 2 weeks after mRNA COVID-19 vaccines: Findings from the CDC v-safe surveillance system

Johanna Chapin-Bardales et al. Vaccine. .

Abstract

Background: Post-authorization monitoring of mRNA-based COVID-19 vaccines is needed to better characterize their reactogenicity. We assessed reactions reported during the 2 weeks after receipt of BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines.

Methods: We monitored persons who enrolled in v-safe after vaccination health checkerSM, a U.S. smartphone-based vaccine monitoring system, after receiving BNT162b2 or mRNA-1273. V-safe participants received text message prompts to complete web-based surveys. We analyzed responses from persons who received BNT162b2 or mRNA-1273 from December 14, 2020 through March 14, 2021 and completed at least one survey by March 28, 2021. We measured the proportion of participants reporting local and systemic reactions solicited in surveys completed days 0 through 7 post-vaccination. For day 14 surveys, participants described new or worsening symptoms in a free-text response. We assessed the proportion of participants reporting new or worsening local and systemic reactions.

Results: One-third of participants were aged <45 years, two-thirds were female, and approximately half received BNT162b2 vaccine. A total of 4,717,908 participants reported during the 7 days after dose 1 and 2,906,377 reported during the 7 days after dose 2. Most reported at least one injection-site reaction (68.5% after dose 1; 72.9% after dose 2) or at least one systemic reaction (50.6% after dose 1; 69.5% after dose 2). Reactogenicity was greater after dose 2 and among mRNA-1273 recipients, persons aged <45 years, and females. New or worsening local and systemic reactions were uncommon during week 2 after either dose; the most frequent were local reactions for dose 1 mRNA-1273 recipients (2.6%). These reactions were reported more often among females after dose 1 mRNA-1273 (3.6%).

Conclusions: During post-authorization monitoring among >4 million vaccinees, local and systemic reactions were commonly reported following mRNA-based vaccines. Reactions were most common during the first week following dose 2 and among persons aged <45 years, females, and mRNA-1273 recipients.

Keywords: COVID-19; COVID-19 vaccines; Reactogenicity; mRNA COVID-19 vaccines.

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Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Percentage of v-safe participants reporting local and systemic reactions to mRNA COVID-19 vaccines at least once during days 0–7 following vaccination by age and sex—CDC v-safe surveillance system, December 14, 2021 through March 28, 2021.
Fig. 2
Fig. 2
Percentage of v-safe participants reporting new or worsening symptoms to mRNA COVID-19 vaccines on day 143 following vaccination by age and sex—CDC v-safe surveillance system, December 14, 2021 through March 28, 2021. 1 Any injection reaction included any of the following: injection site pain, redness, swelling, itching, rash, or COVID arm. 2 Any systemic reactions included any of the following: fatigue, headache, myalgia, chills, fever, joint pain, nausea, vomiting, diarrhea, abdominal pain, and rash outside of injection site. 3 Reactions were quantified by applying text search methods to a free-text response on the day 14 survey that asked about new or worsening symptoms or health conditions since the participant’s last survey.
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