Summary:
The COVID-19 pandemic has caused substantial illness and death worldwide, and also disrupted healthcare staffing due to infections and quarantine. Vaccination has been a critical strategy for controlling the pandemic, with over 13.5 billion doses of approximately 40 vaccines administered globally by October 2023. Rapid vaccine development has significantly reduced mortality. Although COVID-19 vaccines are generally safe, adverse drug reactions (ADRs) have been reported. Most reactions are mild, such as injection-site pain, fever, fatigue, headache, and muscle aches, but serious events like myocarditis, blood clotting disorders, and anaphylaxis are rare. Previous studies also note that ADRs can result in missed work shifts among healthcare workers. This study is a prospective cohort analysis of 3,805 healthcare workers in, examining ADRs, associated sick leave, and antibody levels following primary COVID-19 immunization in 2021. The findings showed that the risk of needing sick leave due to vaccine reactions differed by vaccine type. Only 12% of healthcare workers reported missing work after Comirnaty, while 48% did so after a mixed Vaxzevria/Spikevax schedule. Antibody levels were lower in older individuals and decreased over time, and they also varied depending on the vaccine used. Fever and chills were much more likely after Vaxzevria than Comirnaty, with a tenfold higher risk. Among the mRNA vaccines, Spikevax caused 1.3 to 3.5 times more reactions compared with Comirnaty. These findings indicate that COVID-19 vaccination can lead to considerable work absences among healthcare personnel, with significant variation by vaccine type, age, and sex. The frequency of ADRs observed is higher in COVID-19 vaccines than for other commonly used adult vaccines, highlighting the importance of planning for workforce.
Abstract:
Background: Although SARS-CoV-2 vaccination was a critical component to mitigate impact of the pandemic, it also brought specific challenges related to adverse drug reactions (ADRs) when large cohorts of healthcare workers were vaccinated.
Methods and findings: This study reports solicited ADRs and IgG anti-SARS-CoV-2 levels from 3805 healthcare workers in Sweden following primary immunization during 2021. Differences in systemic reactions at a level where study participants needed sick-leave or rescheduling of work shifts differed substantially between vaccine regimens, ranging from 12 % (Comirnaty) to 48 % (heterologous vaccination with Vaxzevria/Spikevax). Multivariable linear regression showed that the anti-S IgG response was dependent on vaccine label and that higher age and increased time from vaccination significantly correlated with lower antibody titers. Multivariable logistic regression models describing the risk for each ADR category in relation to vaccine label, age, sex, anti-S IgG levels post vaccination and time from vaccination showed vaccine label-dependent statistically significant differences in adjusted odds ratios for wide range of ADR categories, as high as OR 10 (95 % CI 7.6–13.5) for fever and chills when comparing Vaxzevria to Comirnaty. Among the mRNA vaccines, use of Spikevax (compared to Comirnaty) correlated with a statistically significant 1.3 to 3.5-fold increase in adjusted ORs for several ADR categories.
Conclusions: Based on a large cohort of health workers, our study confirms that adverse reactions after COVID-19 vaccination can lead to a substantial amount of missed work shifts, potentially causing organizational-level disturbances in staffing. There are significant differences in ADR frequencies related to vaccine type, age and sex, at overall levels not observed for other commonly used vaccines for adults.
Article Publication Date: 30/06/2025
DOI: 10.1016/j.vaccine.2025.127553
