ArticleBMC medicine2022
Impact of a delayed second dose of mRNA vaccine (BNT162b2) and inactivated SARS-CoV-2 vaccine (CoronaVac) on risks of all-cause mortality, emergency department visit, and unscheduled hospitalization.
Article in BMC medicine, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 13 papers.
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Who cites it
13 citing papers in PubMed, 16 citations in OpenAlex.
- The effect of COVID vaccination timing on the seroprevalence of IgG antibodies: evidence from the Guayas region of Ecuador.Frontiers in public health · 2025Article
- Association of vaccination status and severity of SARS-CoV-2 infections in hospitalized patients.Vaccine: X · 2024Article
- A modeling-based approach to optimize COVID-19 vaccine dosing schedules for improved protection.JCI insight · 2023Article
- Incidence of diabetes following COVID-19 vaccination and SARS-CoV-2 infection in Hong Kong: A population-based cohort study.PLoS medicine · 2023Observational
- Risk of Adverse Events and Delirium after COVID-19 Vaccination in Patients Living with Dementia.Journal of the American Medical Directors Association · 2023Article
- Effectiveness of BNT162b2 after extending the primary series dosing interval in children and adolescents aged 5-17.Nature communications · 2023Article
- A 1-year analysis of adverse events following COVID-19 vaccination in Lebanon: a retrospective study.Journal of pharmaceutical policy and practice · 2023Article
- A modeling-based approach to optimize COVID-19 vaccine dosing schedules for improved protection.medRxiv : the preprint server for health sciences · 2023Article
- Risk of acute liver injury following the mRNA (BNT162b2) and inactivated (CoronaVac) COVID-19 vaccines.Journal of hepatology · 2022Article
- Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: a population-based study of 2.3 million vaccine recipients.BMC medicine · 2022Article
- Effects of spike protein and toxin-like peptides found in COVID-19 patients on human 3D neuronal/glial model undergoing differentiation: Possible implications for SARS-CoV-2 impact on brain development.Reproductive toxicology (Elmsford, N.Y.) · 2022Article
- Adverse events of special interest and mortality following vaccination with mRNA (BNT162b2) and inactivated (CoronaVac) SARS-CoV-2 vaccines in Hong Kong: A retrospective study.PLoS medicine · 2022Observational
- Autoimmune conditions following mRNA (BNT162b2) and inactivated (CoronaVac) COVID-19 vaccination: A descriptive cohort study among 1.1 million vaccinated people in Hong Kong.Journal of autoimmunity · 2022Article
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Authors and funding
12 authors at 4 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundSafety after the second dose of the SARS-CoV-2 vaccine remains to be elucidated, especially among individuals reporting adverse events after their first dose. This study aims to evaluate the impact of a delayed second dose on all-cause mortality and emergency services.
methodsA territory-wide, retrospective cohort of people who had completed two doses of mRNA (BNT162b2) or inactivated SARS-CoV-2 (CoronaVac) vaccine between February 23 and July 3, 2021, in Hong Kong was analyzed, with linkage to electronic health records retrieved from the Hong Kong Hospital Authority. Vaccine recipients were classified as receiving a second dose within recommended intervals (21-28 days for BNT162b2; 14-28 days for CoronaVac) or delayed. Study outcomes were all-cause mortality, emergency department (ED) visits, and unscheduled hospitalizations within 28 days after the second dose of vaccination.
resultsAmong 417,497 BNT162b2 and 354,283 CoronaVac second dose recipients, 3.8% and 28.5% received the second dose beyond the recommended intervals (mean 34.4 and 31.8 days), respectively. During the study period, there were < 5 daily new cases of COVID-19 infections in the community. Delaying the second dose was not associated with all-cause mortality (hazard ratio [HR] = 1.185, 95% CI 0.478-2.937, P = 0.714), risk of ED visit (HR = 0.966, 95% CI 0.926-1.008, P = 0.113), and risk of unscheduled hospitalization (HR = 0.956, 95% CI 0.878-1.040, P = 0.294) compared to that within the recommended interval for CoronaVac recipients. No statistically significant differences in all-cause mortality (HR = 4.438, 95% CI 0.951-20.701, P = 0.058), ED visit (HR = 1.037, 95% CI 0.951-1.130, P = 0.411), and unscheduled hospitalization (HR = 1.054, 95% CI 0.867-1.281, P = 0.597) were identified between people who received a second dose of BNT162b2 within and beyond the recommended intervals.
conclusionsNo significant association between delayed second dose of BNT162b2 or CoronaVac and all-cause mortality, ED visit, and unscheduled hospitalization was observed in the present cohort. Regardless of the recommended or delayed schedule for SARS-CoV-2 vaccination, a second dose of both vaccines should be administered to obtain better protection against infection and serious disease. The second dose should be administered within the recommended interval following the manufacturer's product information, until further studies support the benefits of delaying vaccination outweighing the risks.
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