Do vaccines cause Long COVID?

What the study found regarding prior vaccines came with some important discussion points. First, the authors pointed out that this tie to vaccines could, in part, be due to survivorship bias: those who didn’t receive vaccines were less likely to survive their infections, and, as dead people, could not participate in these studies.

The collider bias, the concept that a third factor that was not controlled for could affect the outcome, could also impact these data, “since the sample included only COVID-19 positive tested patients who accessed the hospital (healthcare workers included).”  The third factor, in this case, is that people who go to the hospital are more likely to seek out medical care, such as going to the doctor for a vaccination.

The study itself also talks about how most other studies show a negative association between COVID-19 vaccination and Long COVID, including a study of 13 million people that shows a decrease in Long COVID risk after vaccination, even if only a slight one.