New data from the VENUS (Vaccine Effectiveness, Networking, and Universal Safety) study in Japan reveal that the risk of developing long COVID is significantly lower when people have been recently vaccinated before infection. The study was published yesterday in Vaccine.
The retrospective study followed participants diagnosed with COVID-19 between August 2020 and December 2022. The incidences of 36 post-COVID-19 conditions were monitored 3, 5, and 8 months after infection.
In total, 84,464 participants were assigned one of three vaccination status groups (distant, intermediate, or recent vaccination), with distant vaccination occurring 365 days or more prior to infection, intermediate being 150 to 364 days after their last vaccine dose, and recent meaning receiving the vaccine 14 to 149 days before infection.
The overall mean age was 53 years, and the mean age by group was 36 years for the distant group, 57 years for the intermediate group, and 65 years for the recent group, the authors said.
Of the 84,464 participants, 9,642 (11.4%) developed post-COVID-19 conditions over 8 months.
Lower risk of heart, respiratory symptoms
The distant vaccination group had a higher risk for most of the 36 long-COVID symptoms compared to the most recent group, especially for respiratory conditions and heart conditions.
“Respiratory conditions are the most common symptom of COVID-19 in the acute phase, and their incidence were the lowest in the recent group in all three follow-up periods,” the authors wrote.
Respiratory conditions are the most common symptom of COVID-19 in the acute phase, and their incidence were the lowest in the recent group in all three follow-up periods.
That pattern was also seen in the most common physical symptoms of long COVID. For fatigue, the hazard ratios (HRs) were 0.64 (95% confidence interval [CI], 0.39 to 1.07) for the intermediate group and 0.55 (95% CI, 0.32 to 0.94) for the recent group. For pain, the HRs were 0.94 (95% CI, 0.73 to 1.20) for the intermediate group and 0.58 (95% CI, 0.44 to 0.77).
Of note, the recent group did not have a significantly lower risk of developing mood disorders (HR, 1.02; 95% CI, 0.57 to 1.81) or depression (HR, 0.96; 95% CI, 0.67 to 1.39) than the distant group.
Overall, the risk of developing 28 out of 36 long-COVID symptoms lessened when vaccines were effective, or up to 5 months after the last dose, the authors said.
“These findings contribute to our understanding of the effectiveness of COVID-19 vaccines against long-term sequelae, and may provide a starting point for more in-depth analyses on the associations between vaccination and specific conditions,” the authors concluded.
