COVID-19 vaccination slashed the risk of experiencing prolonged symptoms by about 27% in fully vaccinated adults who were later infected, estimates a European Centre for Disease Prevention and Control (ECDC) systematic review of 12 studies.

The researchers identified 11 studies on whether COVID-19 vaccination lowers the risk of long COVID, or post-COVID condition (PCC) and 1 study designed to determine whether vaccination reduces both the risk and duration of persistent symptoms. Published after October 2021, the studies used the World Health Organization (WHO) definition of long COVID and were conducted in Europe and similar regions.

The WHO defines long COVID as symptoms 3 months after SARS-CoV-2 infection that last for at least 2 months.

No conclusions about kids, immune-compromised adults. Six studies of adults overall found that full vaccination before infection significantly reduced the odds of developing long COVID compared with no vaccination.

“These studies represented a range of recruitment settings (including both community and hospital settings), time period of infection (and consequently SARS-CoV-2 variant), as well as acute COVID-19 disease severity,” the study authors wrote. “In addition, two of the three studies which did not find that vaccination reduced PCC had small sample sizes, particularly where symptoms were assessed in sub-group analyses.”