Those who were previously infected with COVID-19 were more likely to experience swollen lymph nodes after their first dose of Pfizer's vaccine compared to those without a prior documented infection, according to research published April 22 in the preprint server medRxiv.
Researchers in the U.K. conducted an observational study that looked at adverse events after COVID-19 vaccination. A total of 947 healthcare workers across three hospitals participated in the study by self-reporting symptoms after vaccination. Of those, 265 participants had previously tested positive for the virus.
Overall, those who previously contracted COVID-19 were more likely to report at least one moderate to severe symptom compared to those without a prior infection, at 56 percent and 47 percent, respectively.
Specifically, those in the previous COVID-19 group were significantly more likely to experience lymphadenopathy, or swollen lymph nodes, as well as fever, fatigue, myalgia and arthralgia.
About 4 percent of participants with a COVID-19 history experienced lymphadenopathy, compared to less than 1 percent of those who weren't infected.
"This study of healthcare workers demonstrated that prior COVID-19 infection, but not long COVID-19, is associated with an increased risk of [adverse events] including lymphadenopathy following … vaccination," researchers said.
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