Most COVID-19 vaccine adverse events detected within 48 hours in Ethiopia: implications for cohort event monitoring efficiency in resource-limited settings
Jul 2026· European Journal of Clinical Pharmacology· Vol 82· 0 citations· 31 references
Medicine
TL;DR
Most COVID-19 vaccine adverse events in Ethiopia occurred within 48 h of vaccination, empirically suggesting that extended full-cohort CEM could yield diminishing informational returns in low- and middle-income country settings.
BACKGROUND
Although the impact of COVID-19 vaccination is widely documented in the general population, the evidence on its effectiveness in children under 5 years of age is still limited. In this context, the continuation of vaccination programs in this age group has been debated globally. Consequently, we estimated the effectiveness of the complete 3-dose series of BNT162b2 (Pfizer-BioNTech) in children aged 6 months to 4 years and the complete 2-dose series of CoronaVac (Sinovac) in children aged 3 to 4 in reducing the risk of hospitalizations due to COVID-19-attributed severe acute respiratory infection (SARI) in Brazil.
METHODS
We conducted a retrospective cohort study in 24 Brazilian municipalities, using surveillance data. We evaluated vaccine effectiveness in reducing the incidence rate of COVID-19-attributed SARI hospitalizations from July 2023 to December 2024. Covariate adjustments, defined a priori based on a conceptual model, were implemented using random-effects Poisson regression models.
RESULTS
The cohort comprised 37.7 million person-months of follow-up and 1384 COVID-19-attributed SARI hospitalizations, including 27 associated deaths. The 3-dose series of BNT162b2 vaccine had an effectiveness of 97% (Incidence rate ratio [IRR] 0.03, 95% CI 0.01-0.10) in the group aged 6 months to 4 years, with no significant differences among age-specific estimates. The effectiveness of CoronaVac was small and not statistically significant (IRR 0.96, 95% CI 0.57-1.62).
CONCLUSIONS
In this population-based cohort, completion of the 3-dose BNT162b2 primary series was associated with substantially lower rates of COVID-19-attributed SARI among children aged 6 months to 4 years.
I. N. Schrarstzhaupt, F. A. Diaz-Quijano· Vaccine· 0 citations
BACKGROUND
We estimated the XBB.1.5 vaccine effectiveness (VE) against COVID-19 hospitalization and death in Belgium, Denmark, Italy, Portugal, Spain (Navarre), and Sweden following the 2023-24 fall vaccination campaign among immunocompromised persons (ICPs).
RESEARCH DESIGN AND METHODS
We conducted a multi-country retrospective cohort study using electronic health records. Study sites identified ICPs aged ≥18 years through a common set of immunocompromising conditions and follow-up started the first day of the 2023 vaccination campaign until 12 months later. VE was calculated by time since vaccination (14-59, 60-119, 120-179, 180-365 days after vaccination) for ICPs by pooling study site level confounder adjusted hazard ratios (aHR) of vaccination, estimated with Cox proportional hazards regression models, using a random effect meta-analysis with VE = 100 × (1-pooled aHR).
RESULTS
The XBB.1.5 VE was 52% (95% confidence interval (CI): 41 to 60) and 75% (95%CI: 60 to 84) against hospitalization and death, respectively, 14-59 days after vaccination, and VE decreased with time since vaccination with no remaining protection at 180-365 days after vaccination.
CONCLUSION
Adapted XBB.1.5 vaccine provided moderate protection within 120 days after vaccination against severe COVID-19 outcomes among ICPs aged ≥18 years during a period with BA.2.86/JN.1 replacing the XBB.1.5 variant.
A. Blake, J. Humphreys, K. Olson et al.· Expert Review of Vaccines· 0 citations
Summary Background Vaccination is a vital tool in preventing acute COVID-19 and may confer additional protection against Long COVID, although it is unclear whether this protection wanes over time. Methods We assessed electronic health record (EHR) data from a national, retrospective cohort of patients, comparing the 12-month cumulative incidence of Long COVID (ICD-10 code U09.9) among (A) patients who were vaccinated versus unvaccinated (two or more versus zero doses) and (B) patients diagnosed with acute COVID-19 1–3 months, 3–5 months, or 5–7 months after vaccination. Findings In our binary cohort (n = 519,980), we found that patients who were vaccinated had a lower risk of Long COVID (adjusted risk ratio 0.84 (0.81, 0.88)) or mortality (adjusted risk ratio 0.83 (0.81, 0.86)) than patients who were unvaccinated. In our longitudinal cohort (n = 1,085,291), we did not find significant heterogeneity in Long COVID risk during the seven months following vaccination. Interpretation We found that COVID-19 vaccination was protective against Long COVID, and we did not observe a significant waning of this protection within seven months after vaccination. Funding This research was financially supported by the 10.13039/100000060National Institute of Allergy and Infectious Diseases (1K01AI182501 to Zachary Butzin-Dozier) and a Global Development grant (OPP1165144) from the 10.13039/100000865Bill & Melinda Gates Foundation to the 10.13039/100005595University of California, Berkeley, CA, USA. Individual authors were supported by the following funding sources: 10.13039/100000025NIMHR01131542 (PI Rena C. Patel), Jerrod Anzalone is supported by the 10.13039/100000057National Institute of General Medical Sciences, U54 GM115458, which funds the Great Plains IDeA-CTR Network. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Z. Butzin-Dozier, Yunwen Ji, Lin-Chiun Wang et al.· EBioMedicine· 0 citations
Yisheng Jun’an® rabies vaccine exhibits a favorable safety profile with mild-to-moderate reactions, support its use in post-exposure prophylaxis, supporting its use in post-exposure prophylaxis.
Zhijie Cui, Lianfu Wang, Zhiyuan Ran et al.· Frontiers in Public Health· 0 citations
Malaria remains a leading cause of child mortality in sub-Saharan Africa. Cameroon introduced the RTS,S/AS01 malaria vaccine in 2024, but real-world evidence on its early effects, coverage, and safety remains limited. This study evaluated these parameters among children under 36 months in the high-transmission Soa Health District. A community-based analytical cross-sectional study was conducted from February to May 2025. Households were selected by stratified cluster sampling (62 clusters, 622 participants). Children aged < 36 months who had resided in the district for ≥ 3 months were eligible. Vaccination status and malaria episodes (confirmed by rapid diagnostic test or microscopy) during the preceding six months were abstracted from cards. Primary exposure was ≥ 2 doses of RTS,S/AS01; primary outcome was documented malaria episodes. Multivariable modified Poisson regression with robust standard errors was used to estimate risk ratios (RR) adjusted for age, breastfeeding, insecticide-treated net (ITN) use, and intermittent preventive treatment in infancy (IPTi). The effect of the vaccine was measured as (1–adjusted RR) × 100. Coverage and adverse events were also assessed. Among 622 children (mean age 17.9 months, 51.4% female), documented coverage of dose 1 was 56·8% (95% CI 53.5–61.7), dropping to 46·6% for dose 2 and 39·0% for dose 3. Perceived free access (aRR 1.97, 95% CI 1.47–2.64) and knowledge of a nearby vaccination facility (aRR 1.86, 95% CI 1.41–2.45) were strongly associated with uptake. In the cross-sectional analysis, children who received ≥ 2 doses were associated with a 50% lower occurrence of malaria episodes (aRR 0.50, 95% CI 0.34–0.73, p = 0.001) compared with those receiving ≤ 1 dose. Minor adverse events occurred in 27% (fever 93%, injection site swelling 10%). In this high-burden Cameroonian setting, two or more doses of RTS,S/AS01 were associated with a lower occurrence of malaria episodes favourable safety profile. Coverage remains suboptimal, and dropout is high. Ensuring free access and strengthening community awareness are critical for maximising vaccine uptake.
C. Bekolo, Gladys Aimée Simo Zekeng, Paul Onambele et al.· Tropical Medicine and Health· 0 citations
AIM
To compare the burden and severe outcomes among patients hospitalised for influenza to those hospitalised for coronavirus disease 2019 (COVID-19) in Greece.
METHODS
The study was conducted in four hospitals from November 2024 to May 2025. Main outcomes were length of stay (LOS) and severe outcomes (admission to intensive care unit, invasive mechanical ventilation, in-hospital death). The associations between LOS and adverse outcomes with COVID-19 or influenza were estimated with multivariable negative binomial and logistic regression models.
RESULTS
We studied 621 patients [mean age: 75.6 years; 564 (90.8%) with at least one comorbidity], of whom 43 (6.9%) died. In total, 358 patients were admitted for COVID-19 and 263 for influenza. Influenza patients had a mean LOS of 10.7 days compared with 7.5 days among COVID-19 patients (p-value <0.001), while severe outcomes were similar across the two groups. Adjusted models yielded similar findings, with influenza patients having significantly longer LOS [incidence rate ratio (IRR): 1.47; 95% confidence interval (CI): 1.03-2.10] compared with COVID-19 patients, and no difference in the odds of experiencing any severe outcome [adjusted odds ratio (aOR) = 2.10; 95% CI: 0.88-5.04]. Pneumonia was associated with increased odds for any severe outcome (aOR: 7.55; 95% CI: 1.10-52.33) and longer LOS (IRR: 2.09; 95% CI: 1.39-3.15) overall and within diagnostic subgroups. Among COVID-19 patients, those with ≥1 COVID-19 vaccine dose had reduced odds for experiencing any severe outcome (aOR = 0.38; 95% CI: 0.15-0.96) compared with unvaccinated patients.
CONCLUSIONS
In 2024-2025, influenza patients had significantly longer LOS than COVID-19 patients, while severe outcomes were not significantly different between the two groups.
Helena C. Maltezou, V. Rapti, Ilektra Tseliou et al.· Infectious Diseases· 0 citations
