To date, little is known about the evidence of a potential risk of psychiatric adverse events following COVID-19 vaccination in large populations with adequate study design.

To investigate whether COVID-19 vaccination is associated with increased risk of psychiatric adverse events.

We used South Korea’s linkage database to obtain registry data and claims data from 2019 to 2021, and conducted a population-based self-controlled case series study including 11 751 806 individuals. Primary outcomes included anxiety/nervousness, mood disorders, perceptual disturbances/psychoses, aggression/behavioural disturbances, cognitive impairments and sleep disorders within 21 days of COVID-19 vaccination. Secondary outcomes were the stratified primary outcomes according to each individual’s psychiatric history. Conditional Poisson regression was used to estimate incidence rate ratios (IRR) and 95% confidence intervals.

COVID-19 vaccination did not increase the rate of anxiety and nervousness (adjusted IRR 0.95, 95% CI 0.95–0.96), mood disorders (adjusted IRR 0.75, 95% CI 0.75–0.76), perceptual disturbances and psychoses (adjusted IRR 0.72, 95% CI 0.70–0.74), aggression and behavioural disturbances (adjusted IRR 0.93, 95% CI 0.89–0.97), cognitive impairment (adjusted IRR 0.68, 95% CI 0.67–0.69) or sleep disorders (adjusted IRR 0.90, 95% CI 0.89–0.91). Secondary outcomes were consistent with the primary outcome, although the adjusted IRRs for anxiety and nervousness (adjusted IRR 1.17, 95% CI 1.15–1.18) and sleep disorders (adjusted IRR 1.07, 95% CI 1.06–1.09) were statistically significant in individuals with no history of psychiatric disorders. Sensitivity analyses showed consistent results with our main findings.

Our findings provide short-term safety profiles for COVID-19 vaccines regarding psychiatric adverse events. Continuous monitoring of anxiety/nervousness or sleep disorders after COVID-19 vaccination is required regardless of history of psychiatric comorbidities.

Patients with bipolar disorder (BPD) are prone to engage in risk-taking behaviours and self-harm, contributing to higher risk of traumatic injuries requiring medical attention at the emergency room (ER).We hypothesize that pharmacological treatment of BPD could reduce the risk of traumatic injuries by alleviating symptoms but evidence remains unclear. This study aimed to examine the association between pharmacological treatment and the risk of ER admissions due to traumatic injuries.

Individuals with BPD who received mood stabilizers and/or antipsychotics were identified using a population-based electronic healthcare records database in Hong Kong (2001–2019). A self-controlled case series design was applied to control for time-invariant confounders.

A total of 5040 out of 14 021 adults with BPD who received pharmacological treatment and had incident ER admissions due to traumatic injuries from 2001 to 2019 were included. An increased risk of traumatic injuries was found 30 days before treatment [incidence rate ratio (IRR) 4.44 (3.71–5.31), p < 0.0001]. After treatment initiation, the risk remained increased with a smaller magnitude, before returning to baseline [IRR 0.97 (0.88–1.06), p = 0.50] during maintenance treatment. The direct comparison of the risk during treatment to that before and after treatment showed a significant decrease. After treatment cessation, the risk was increased [IRR 1.34 (1.09–1.66), p = 0.006].

This study supports the hypothesis that pharmacological treatment of BPD was associated with a lower risk of ER admissions due to traumatic injuries but an increased risk after treatment cessation. Close monitoring of symptoms relapse is recommended to clinicians and patients if treatment cessation is warranted.

The risk of antipsychotic-associated cardiovascular and metabolic events may differ among countries, and limited real-world evidence has been available comparing the corresponding risks among children and young adults. We, therefore, evaluated the risks of cardiovascular and metabolic events in children and young adults receiving antipsychotics.

We conducted a multinational self-controlled case series (SCCS) study and included patients aged 6–30 years old who had both exposure to antipsychotics and study outcomes from four nationwide databases of Taiwan (2004–2012), Korea (2010–2016), Hong Kong (2001–2014) and the UK (1997–2016) that covers a total of approximately 100 million individuals. We investigated three antipsychotics exposure windows (i.e., 90 days pre-exposure, 1–30 days, 30–90 days and 90 + days of exposure). The outcomes were cardiovascular events (stroke, ischaemic heart disease and acute myocardial infarction), or metabolic events (hypertension, type 2 diabetes mellitus and dyslipidaemia).

We included a total of 48 515 individuals in the SCCS analysis. We found an increased risk of metabolic events only in the risk window with more than 90-day exposure, with a pooled IRR of 1.29 (95% CI 1.20–1.38). The pooled IRR was 0.98 (0.90–1.06) for 1–30 days and 0.88 (0.76–1.02) for 31–90 days. We found no association in any exposure window for cardiovascular events. The pooled IRR was 1.86 (0.74–4.64) for 1–30 days, 1.35 (0.74–2.47) for 31–90 days and 1.29 (0.98–1.70) for 90 + days.

Long-term exposure to antipsychotics was associated with an increased risk of metabolic events but did not trigger cardiovascular events in children and young adults.