Burden and Impact of Reactogenicity among Adults Receiving COVID-19 Vaccines in the United States and Canada: Results from a Prospective Observational Study

Abstract

As SARS-CoV-2 variants continue to emerge, vaccination remains a critical tool to reduce the COVID-19 burden. Vaccine reactogenicity and the impact on work productivity/daily activities are recognized as contributing factors to vaccine hesitancy. To encourage continued COVID-19 vaccination, a more complete understanding of the differences in reactogenicity and impairment due to vaccine-related side effects across currently available vaccines is necessary. The 2019nCoV-406 study (n = 1367) was a prospective observational study of reactogenicity and associated impairments in adults in the United States and Canada who received an approved/authorized COVID-19 vaccine. Compared with recipients of mRNA COVID-19 booster vaccines, a smaller percentage of NVX-CoV2373 booster recipients reported local and systemic reactogenicity. This study’s primary endpoint (percentage of participants with ≥50% overall work impairment on ≥1 of the 6 days post-vaccination period) did not show significant differences. However, the data suggest that NVX-CoV2373 booster recipients trended toward being less impaired overall than recipients of an mRNA booster; further research is needed to confirm this observed trend. The results of this real-world study suggest that NVX-CoV2373 may be a beneficial vaccine option with limited impact on non-work activities, in part due to the few reactogenicity events after vaccination.

Reactogenicity Differences between COVID-19 Vaccines: A Pro-spective Observational Study in the United States and Canada

“…The post-primary series population included 1130 participants, 303 of whom received NVX-CoV2373 and 827 who received an mRNA vaccine during 110 the study period. Baseline demographics and clinical characteristics were generally balanced between vaccine groups, 111 as reported previously [17]; however, some differences between the NVX-CoV2373 and mRNA vaccine groups were 112 observed related to ethnicity (Table 1). A higher proportion of Hispanic, Latin American, or Latinx (50.8%) and White 113 (50.2%) participants received NVX-CoV2373 versus an mRNA vaccine (25.0% and 33.6%, respectively).…”

“…Participants completed baseline/screening questionnaires on the day of their vaccine (day 0) and a daily diary for the following 6 days that included a Vaccine Symptoms Diary. Further details on participant inclusion criteria and study methods are available in the prior publication [17]. Written informed consent was provided by each participant prior to receipt of their requested vaccine dose and survey completion.…”

“…Due to low numbers receiving other vaccine types, only data related to NVX-CoV2373 or the mRNA vaccines (BNT162b2 and mRNA-1273) were included in this analysis. Estimation of the sample size required to power the primary objectives in the main study was described previously [17].…”

“…Comparative analyses were adjusted to address potential confounding using inverse probability of treatment weighting (IPTW). As described previously [17], each participant was assigned a propensity score based on a select group of demographic and clinical characteristics identified using standardized differences. The present analysis used the following covariates in the IPTW model: country (US vs Canada), prior COVID-19 diagnosis (yes vs no), race (Asian, White), job category (professional), work at home (yes, no, or prefer not to answer), gender identity (male, female), and scheduled to work in the next 24 h (yes vs no).…”

“…Of note, studies comparing reactogenicity have generally found a higher incidence of local and systemic events following receipt of mRNA COVID-19 vaccines compared with influenza and other non-COVID-19 vaccines, as well as a higher frequency of reactogenicity-associated medication use, sick leave, and doctor's visits [15,16]. COVID-19 vaccine-related reactogenicity events can affect work and other daily activities, leading to absenteeism from work [17,18] and presenteeism [17,19], as well as vaccine hesitancy [20][21][22][23][24]. Indeed, concern over vaccine side effects was found to be the most common reason for refusing an updated COVID-19 vaccine [24].…”