Narrative Review of the Evolution of COVID-19 Vaccination Recommendations in Countries in Latin America, Africa and the Middle East, and Asia

Global trends in COVID-19 incidence and case fatality rates (2019-2023): a retrospective analysis

Objectives

Analyzing and comparing COVID-19 infection and case-fatality rates across different regions can help improve our response to future pandemics.

Methods

We used public data from the WHO to calculate and compare the COVID-19 infection and case-fatality rates in different continents and income levels from 2019 to 2023.

Results

The Global prevalence of COVID-19 increased from 0.011 to 0.098, while case fatality rates declined from 0.024 to 0.009. Europe reported the highest cumulative infection rate (0.326), with Africa showing the lowest (0.011). Conversely, Africa experienced the highest cumulative case fatality rates (0.020), with Oceania the lowest (0.002). Infection rates in Asia showed a steady increase in contrast to other continents which observed initial rises followed by decreases. A correlation between economic status and infection rates was identified; high-income countries had the highest cumulative infection rate (0.353) and lowest case fatality rate (0.006). Low-income countries showed low cumulative infection rates (0.006) but the highest case fatality rate (0.016). Initially, high and upper-middle-income countries experienced elevated initial infection and case fatality rates, which subsequently underwent significant reductions.

Conclusions

COVID-19 rates varied significantly by continent and income level. Europe and the Americas faced surges in infections and low case fatality rates. In contrast, Africa experienced low infection rates and higher case fatality rates, with lower- and middle-income nations exceeding case fatality rates in high-income countries over time.

Severe COVID-19 Outcomes in Five Latin American Countries in the Postvaccination Era

We conducted a multicountry retrospective study using data from COVID-19 national surveillance databases to analyze clinical profiles, hospitalization rates, intensive care unit (ICU) admissions, utilization of ventilatory support, and mortality rates in five Latin American countries in the context of COVID-19 vaccination implementation. We analyzed the sociodemographic characteristics, comorbidities, clinical outcomes, and vaccination status of laboratory-confirmed COVID-19 cases from January 2021 to December 2022. We calculated the yearly and quarterly hospitalization rates per 1000 confirmed COVID-19 cases and ICU admissions, use of mechanical ventilators, and mortality rates per 1000 hospitalized cases, with their corresponding 95% confidence interval (CI) of 38,852,831 confirmed COVID-19 cases. Rates of hospitalization, ICU admission, ventilatory support, and death were higher among males than among females (38.2 vs. 32.4, 148.4 vs. 117.7, 282.9 vs. 236.2, and 346.9 vs. 320.1 per 1000, respectively); higher in 2021 than in 2022 (50.7 vs. 19.9, 207.8 vs. 58.2, 441.5 vs. 114.9, and 352.5 vs. 285.2 per 1000, respectively); and in the >50 age group (range: 5.7-18.6, 20.1-71.5, 12.2-67.9, and 353.1-577.4, per 1000) than the <50 age group (range: 2.2-9.3, 5.4-33.2, 41.4-135.8, and 22-243.5 per 1000). Hypertension and diabetes mellitus were the most common comorbidities in Mexico and Colombia. Prevention and treatment strategies for these case profiles could bring benefits from a public health perspective.

Retrospective Analysis of Clinical Characteristics and Disease Outcomes in Children and Adolescents Hospitalized Due to COVID-19 Infection in Tunisia

Due to low susceptibility of coronavirus disease of 2019 (COVID-19) in children, limited studies are available regarding COVID-19 in the pediatric population in Tunisia. The current study evaluated the incidence, clinical characteristics, and outcomes of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection among children hospitalized at Béchir Hamza Children's Hospital. A retrospective cohort analysis was conducted using the hospital database between March 2020 and February 2022 with children aged ≤15 years with SARS-CoV-2 infection (confirmed by RT-PCR). A total of 327 COVID-19 hospitalized patients with a mean age of 3.3 years were included; the majority were male. Neurological disease (20%) was the most common comorbidity, while fever (95.3%) followed by cough (43.7%) and dyspnea (39.6%) were the most frequent symptoms reported. Severe disease with oxygen requirement occurred in 30% of the patients; 13% were admitted in the Intensive Care Unit. The overall incidence rate of COVID-19 hospitalization (in Tunis governorates) was 77.02 per 100,000 while the inpatient case fatality rate was 5% in the study population. The most prevalent circulating variant during our study period was Delta (48.8%), followed by Omicron (26%). More than 45% of the study population were <6 months and one-fourth (n = 25, 26.5%) had at least one comorbidity. Thus, the study findings highlight the high disease burden of COVID-19 in infants.

Vaccine-Induced Immune Thrombotic Thrombocytopenia: Clinicopathologic Features and New Perspectives on Anti-PF4 Antibody-Mediated Disorders

INTRODUCTION

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet severe adverse complication first identified during the global vaccination effort against SARS-CoV-2 infection, predominantly observed following administration of the ChAdOx1-S (Oxford-AstraZeneca) and Ad26.CoV2.S (Johnson & Johnson/Janssen) adenoviral vector-based vaccines. Unlike other anti-platelet factor 4 (PF4) antibody-mediated disorders, such as heparin-induced thrombocytopenia (HIT), VITT arises with the development of platelet-activating anti-PF4 antibodies 4-42 days post-vaccination, typically featuring thrombocytopenia and thrombosis at unusual sites.

AIM

To explore the unique properties, pathogenic mechanisms, and long-term persistence of VITT antibodies in patients, in comparison with other anti-PF4 antibody-mediated disorders.

DISCUSSION

This review highlights the complexity of VITT as it differs in antibody behavior and clinical presentation from other anti-PF4-mediated disorders, including the high incidence rate of cerebral venous sinus thrombosis (CVST) and the persistence of anti-PF4 antibodies, necessitating a re-evaluation of long-term patient care strategies. The nature of VITT antibodies and the underlying mechanisms triggering their production remain largely unknown.

CONCLUSION

The rise in awareness and subsequent prompt recognition of VITT is paramount in reducing mortality. As vaccination campaigns continue, understanding the role of adenoviral vector-based vaccines in VITT antibody production is crucial, not only for its immediate clinical implications, but also for developing safer vaccines in the future.

Safety and immunogenicity of the third and fourth doses of vaccine against SARS-CoV-2 following a 2-dose regimen of inactivated whole-virion SARS-CoV-2 vaccine

This study followed healthcare personnel (HCP) who had completed a primary series of CoronaVac and then received the third and fourth doses of COVID-19 vaccine. The primary objective was to determine the seroconversion rate of neutralizing antibodies against wild-type SARS-CoV-2 and VOCs at day 28 after the third dose of vaccine and day 28 after the fourth dose of vaccine. This prospective cohort study was conducted at Maharaj Nakorn Chiang Mai Hospital, a tertiary care hospital affiliated to Chiang Mai University from July 2021 to February 2022. Two hundred and eighty-three participants were assessed for eligibility; 142 had received AZD1222 and 141 BNT162b2 as the third dose. Seroconversion rates using a 30% inhibition cutoff value against wild-type SARS-CoV-2 were 57.2%, 98.6%, 97.8%, and 98.9% at points before and after the third dose, before and after the fourth dose, respectively among those receiving AZD1222 as the third dose. Frequencies were 31.9%, 99.3%, 98.9%, and 100% among those receiving BNT162b2 as the third dose, respectively. The seroconversion rates against B.1.1.529 [Omicron] were 76.1% and 90.2% (p-value 0.010) at 4 weeks after the third dose in those receiving AZD1222 and BNT162b2 as the third dose, respectively. After a booster with the mRNA vaccine, the seroconversion rates increased from 21.7 to 91.3% and from 30.4 to 91.3% in those receiving AZD1222 and BNT162b2 as the third dose, respectively. No serious safety concerns were found in this study. In conclusion, antibody responses waned over time regardless of the vaccine regimen. The booster dose of the vaccine elicited a humoral immune response against SARS-CoV-2 including SARS-CoV-2 variants of concern, including B.1.1.529 [Omicron], which was circulating during the study period. However, the results might not be extrapolated to other Omicron sublineages.

Burden of COVID-19 during the omicron predominance in Brazil: a nationwide retrospective database study

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has imposed significant burden on Brazil's health system. This study aimed to examine clinical characteristics, overall vaccine uptake, and to assess healthcare resource utilization (HCRU) and costs associated with acute COVID-19 in Brazil during the Omicron predominant period.

METHODS

A nationwide retrospective study was conducted using various Brazilian databases including, COVID-19 related databases, public health systems, and other surveillance/demographic datasets. Individuals with positive COVID-19 test results between January 1 2022 and April 30 2022, during Omicron BA.1/BA.2 wave, were identified. Patients' demographics, vaccine uptake, HCRU and corresponding costs were described by age groups.

RESULTS

A total of 8,160,715 (3.80%) COVID-19 cases were identified in the study cohort, ranging from 2.43% in <5 years to 62.05% in 19-49 years. The uptake of partial (Dose 1) or full immunization (Dose 2) was less than 0.1% in children aged <5 years, whereas in individuals ≥ 19 years, it exceeded 89.78% for Dose 1 and 84.07% for Dose 2. Overall booster vaccine uptake was 38.06%, which was significantly higher among individuals aged ≥ 65 years, surpassing 74.79%. Regardless of vaccination status, 87.2% cases were symptomatic, and 1.48% were hospitalized due to acute COVID-19 (<5 years: 2.33%, 5-11 years: 0.99%, 12-18 years: 0.32%, 19-49 years: 0.40%; 50-64 years: 1.50%, 65-74 years: 5.43%, and ≥ 75 years: 17.89%). Among the hospitalized patients (n = 120,450), 32.57% were admitted to ICU, of whom 31,283 (79.75%) individuals required mechanical ventilation (MV) support. The average cost per day in normal ward and ICU without MV in public/general hospital settings was $104.36 and $302.81, respectively. While average cost per day in normal ward and ICU with MV was $75.91 and $301.22 respectively.

CONCLUSIONS

This study quantified the burden of COVID-19 in Brazil, suggesting substantial healthcare resources required to manage the COVID-19 pandemic.