Post‐Covid‐19‐vaccination adverse events and healthcare utilization among individuals with or without previous SARS‐CoV‐2 infection

Abstract

Background Post‐marketing pharmacovigilance data are scant on the safety of Covid‐19 vaccines among people with previous SARS‐CoV‐2 infection compared with ordinary vaccine recipients. We compared the post‐vaccination adverse events of special interests (AESI), accident and emergency room (A&E) visit, and hospitalization between these two groups. Methods We conducted a retrospective cohort study using a territory‐wide public healthcare database with population‐based vaccination records in Hong Kong. Results In total, 3922 vaccine recipients with previous SARS‑CoV‑2 infection and 1,137,583 vaccine recipients without previous SARS‑CoV‑2 infection were included. No significant association was observed between previous SARS‑CoV‑2 infection and AESI or hospitalization. Previous SARS‑CoV‑2 infection was significantly associated with a lower risk of A&E visit (CoronaVac: hazard ratios [HR] = 0.56, 95% confidence intervals [CI]: 0.32–0.99; Comirnaty: HR = 0.62, 95% CI: 0.47–0.82). Conclusion No safety signal of Covid‐19 vaccination was detected from the comparison between vaccine recipients with previous SARS‐CoV‐2 infection and those without infection.

Risk of acute liver injury following the mRNA (BNT162b2) and inactivated (CoronaVac) COVID-19 vaccines

“…However, our previous publications have shown that vaccine recipients in Hong Kong were younger, healthier, and on fewer medications than unvaccinated people during the observation period. 12 , 15 , 16 Hence, our findings may not be fully applicable to people in poor health. Nevertheless, a “healthy vaccine recipient effect” is unlikely to affect our results because of the within-person comparison nature of the SCCS.…”

“…Firstly, our study reported a low rate of chronic liver disease among vaccinated individuals with incident ALI so it is possible that some underlying liver diseases may have been underdiagnosed. However, our previous publications have shown that vaccine recipients in Hong Kong were younger, healthier, and on fewer medications than unvaccinated people during the observation period (12,15,16).…”

“…Records were linked using a unique de-identified mapping key. These 2 linked sources of data have been extensively used for COVID-19 vaccine pharmacovigilance research [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] and drug-induced liver injury research. 26 …”

Autoimmune conditions following mRNA (BNT162b2) and inactivated (CoronaVac) COVID-19 vaccination: A descriptive cohort study among 1.1 million vaccinated people in Hong Kong

“…EMRs from the HA were linked with the DH vaccination records using de-identified non-reversible pseudo-ID to protect patient privacy. The database has been use for several COVID-19 vaccine safety assessment in HK [ 8 , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] ].…”

Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: a population-based study of 2.3 million vaccine recipients

“…All prescriptions dispensed by HA pharmacies are recorded. These two linked data sources have been recently used to conduct population-based pharmacovigilance studies of COVID-19 vaccines [14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”