ChAdOx1 nCoV-19 Vaccine Research Articles

Kaposi Sarcoma as a Possible Cutaneous Adverse Effect of ChAdOx1 nCov-19 Vaccine: A Case Report

The COVID-19 pandemic prompted the rapid development of vaccines, including the ChAdOx1 nCov-19 (AstraZeneca) vaccine. While effective, adverse effects have been reported, including cutaneous manifestations. Kaposi sarcoma (KS), a vascular tumor linked to Kaposi sarcoma herpesvirus/human herpesvirus 8 (HHV-8), has seen increased detection during the pandemic. This study reports a case of classic cutaneous KS in a 79-year-old male following the first dose of the ChAdOx1 nCov-19 vaccine, without prior SARS-CoV-2 infection. The patient developed multiple reddish-blue papules on his legs and feet, confirmed as KS through histopathology. Treatment included radiotherapy and sequential chemotherapy with Doxorubicin. The potential reactivation of latent HHV-8 by the vaccine is explored through mechanisms involving the SARS-CoV-2 spike protein and adenovirus vector, which may induce immune responses and inflammatory pathways. Although establishing a direct causal link remains challenging, the case highlights the need for vigilance regarding KS reactivation post-vaccination. Further large-scale studies are warranted to elucidate the relationship between COVID-19 vaccines and latent virus reactivation, ensuring comprehensive safety assessments and informed public health decisions.

A pseudotyped adenovirus serotype 5 vector with serotype 49 fiber knob is an effective vector for vaccine and gene therapy applications

Adenoviruses (Ad) have demonstrated significant success as replication-deficient (RD) viral vectored vaccines, as well as broad potential across gene therapy and cancer therapy. Ad vectors transduce human cells via direct interactions between the viral fiber knob and cell surface receptors, with secondary cellular integrin interactions. Ad receptor usage is diverse across the extensive phylogeny. Commonly studied human Ad serotype 5 (Ad5), and chimpanzee Ad-derived vector “ChAdOx1” in licensed ChAdOx1 nCoV-19 vaccine, both form primary interactions with the Coxsackie and Adenovirus Receptor (CAR), which is expressed on human epithelial cells and erythrocytes. CAR usage is suboptimal for targeted gene delivery to cells with low/negative CAR expression, including human dendritic cells (DCs) and vascular smooth muscle cells (VSMCs). We evaluated the performance of a RD Ad5 vector pseudotyped with the fiber knob of human Ad serotype 49, termed Ad5/49K vector. Ad5/49K demonstrated superior transduction of murine and human DCs over Ad5, which translated into significantly increased T cell immunogenicity when evaluated in a mouse cancer vaccine model using 5T4 tumour-associated antigen. Additionally, Ad5/49K exhibited enhanced transduction of primary human VSMCs. These data highlight the potential of Ad5/49K vector for both vascular gene therapy applications and as a potent vaccine vector.

Ounis Syndrome with Syncope, Yasser’s Hypocalcemic Sign, and Possible Pulmonary Embolism after AstraZeneca ChAdOx1 nCoV-19 Vaccine in Elderly; Risk and Management

ounis Syndrome with Syncope, Yasser’s Hypocalcemic Sign, and Possible Pulmonary Embolism after AstraZeneca ChAdOx1 nCoV-19 Vaccine in Elderly; Risk and Management

Calcifediol boosts efficacy of ChAdOx1 nCoV-19 vaccine by upregulating genes promoting memory T cell responses

The ChAdOx1 nCoV-19 (COVISHIELD) vaccine has emerged as a pivotal tool in the global fight against the COVID-19 pandemic. In our previous study eligible subjects were supplemented with calcifediol, a direct precursor to the biologically active form of vitamin D, calcitriol with an objective to enhance the immunogenicity of the COVISHIELD vaccine. Herein we investigated the effects of calcifediol supplementation on gene expression profiles in individuals who received the COVISHIELD vaccine. Peripheral blood mononuclear cells were isolated from vaccinated individuals with and without calcifediol supplementation at baseline, 3rd and 6th month, and the gene expression profiles were analyzed using high-throughput sequencing. The results revealed distinct patterns of gene expression associated with calcifediol supplementation, suggesting potential molecular mechanisms underlying the beneficial effects of calcifediol in improving the efficacy of COVISHIELD vaccine via augmentation of T cell activation, proliferation and T cell memory responses. Additionally, there was upregulation of NOD like receptor, JAK/STAT and TGF beta signaling pathways. Calcifediol supplementation in vaccinated individuals also downregulated the pathways related to the Coronavirus disease. Taken together, our findings provide valuable insights into the interplay between vitamin D receptor (VDR) signaling and vaccine-induced immune responses and offer another approach in improving vaccination induced antiviral responses.

Vaccine Adverse Effects Following Covishield among Health-care Workers in Central India

Abstract Introduction: This study aims to analyze common adverse effects following immunization that are temporally associated after receiving the above 2 doses of ChAdOx1 nCoV-19 Vaccine (Covishield) COVID-19 vaccines among health-care worker from January 2021 to April 2021, in the central region of India in a tertiary care hospital. Materials and Methods: A surveillance-based study was conducted between January 2021 and April 2021 among the health-care worker of the tertiary care hospital in the central part of India. The study was designed to identify the adverse effects reported after receiving a ChAdOx1 nCoV-19 Vaccine (Covishield) COVID-19 vaccination and demographic details were collected. Results: Within 48 h of the initial immunization dose, 651 mild adverse effects in all participants were documented. Headache (n = 168, 16%), fever (n = 105, 10%), fatigue (n = 115, 11%), and muscular discomfort (n = 115, 10%) were among the frequent side effects. One hundred and five minor adverse effects were reported between 3 and 7 days. No major adverse effects were observed after the first and second doses of vaccine. Conclusion: The first 48 h were the most common observational period for the short-term adverse effects of both dosages. After 15 days of both doses, the incidence declined for consecutive weeks until it was completely absent. The symptoms were transient and of a minor in nature. There were no documented severe vaccine-related side effects. Our research demonstrated that the vaccination had a decreased adverse event profile, was safe, and was well-tolerated.

SARS-CoV-2-Specific Antibodies, B Cell and T Cell Immune Responses after ChAdOx1 nCoV-19 Vaccination in Solid Organ Transplant Recipients.

Immunization against SARS-CoV-2 is essential for vulnerable solid organ transplant (SOT) recipients who are at risk of infection. However, there are concerns about suboptimal immunogenicity, especially in humoral immunity (HMI), and limited exploration of cell-mediated immune (CMI) responses. The primary objective of this study was to assess the immunogenicity of ChAdOx1 nCoV-19 vaccination in SOT recipients. The secondary endpoint was to evaluate factors that affect immunogenicity and adverse events (AEs) following immunization in SOT recipients. All adult SOT recipients who received the two-dose ChAdOx1 nCoV-19 vaccine at a 12-week interval underwent measurements of HMI by evaluating anti-receptor-binding domain (RBD) IgG levels and CMI by investigating SARS-CoV-2-specific T cell and B cell responses before and after complete vaccination, around 2-4 weeks post-vaccination, and compared to controls. AEs were monitored in all participants. The study included 63 SOT recipients: 44 kidney recipients, 16 liver recipients, and 3 heart transplant recipients, along with 11 immunocompetent controls. Among SOT recipients, 36% were female, and the median (IQR) age was 52 (42-61). The median (IQR) time since transplant was 55 (28-123) months. After the second dose, the median (IQR) anti-RBD antibody levels were significantly lower in SOT recipients compared to those in the control group (8.3 [0.4-46.0] vs. 272.2 [178.1-551.6] BAU/mL, p < 0.01). This resulted in a seroconversion rate (anti-RBD antibody > 7.1 BAU/mL) of 51% among SOT recipients and 100% among controls (p = 0.008). Receiving the vaccine beyond one year post-transplant significantly affected seroconversion (OR 9.04, 95% CI 1.04-78.56, p = 0.046), and low-dose mycophenolic acid marginally affected seroconversion (OR 2.67, 95% CI 0.89-7.96, p = 0.079). RBD-specific B cell responses were also significantly lower compared to those in the control group (0 [0-4] vs. 10 [6-22] SFUs/106 PBMCs, p = 0.001). Similarly, S1- and SNMO-specific T cell responses were significantly lower compared to those in the control group (48 [16-128] vs. 216 [132-356] SFUs/106 PBMCs, p = 0.004 and 20 [4-48] vs. 92 [72-320] SFUs/106 PBMCs, p = 0.004). AEs were generally mild and spontaneously resolved. SOT recipients who received the full two-dose ChAdOx1 nCoV-19 vaccine demonstrated significantly diminished HMI and CMI responses compared to immunocompetent individuals. Consideration should be given to administering additional vaccine doses or optimizing immunosuppressant regimens during vaccination (Thai Clinical Trial Registry: TCTR20210523002).

Plasmacytoid dendritic cells are central regulators of the humoral ChAdOx1 nCoV-19 vaccine response in a human tonsil organoid model

Abstract Studying human vaccine responses is limited by the difficulty of access to secondary lymphoid tissues. To overcome this, we have optimized a human tonsil organoid model to investigate the processes that regulate the humoral responses to the ChAdOx1 nCoV-19 vaccine. Stimulation of tonsil cultures with ChAdOx1 nCoV-19 induced broad innate immune activation and cytokine secretion within 24 hours. This induced (global and antigen-specific) B cell activation and spike-specific antibody secretion over the following 14-day culture period. Stimulation with an irrelevant ChAdOx1 GFP vector did not induce spike-specific antibody secretion. Plasmacytoid dendritic cells (pDCs) showed the highest rate of transduction and activation. Critically, pDC-depletion decreased both innate and humoral responses. IFN-⍺ blockade phenocopied pDC depletion while supplementing IFN-⍺ to pDC-depleted cultures rescued humoral responses. IL-6 was also critical for optimal humoral responses, and its production was modulated in an IFN-⍺-dependent manner even in the absence of pDCs, suggesting cross-talk of multiple key signaling pathways. Overall, this model reveals a critical role for pDCs in inducing humoral responses to ChAdOx1 nCoV-19, primarily through IFN-⍺. IFN-⍺ appears to act directly and indirectly through IFN-induced IL-6 secretion to augment the humoral response. This model has the potential for studying other vaccine platforms.

A phase 3 randomized controlled trial of a COVID-19 recombinant vaccine S-268019-b versus ChAdOx1 nCoV-19 in Japanese adults.

We assessed S-268019-b, a recombinant spike protein vaccine with a squalene-based adjuvant, for superiority in its immunogenicity overChAdOx1 nCoV-19 vaccine among adults in Japan. In this multicenter, randomized, observer-blinded, phase 3 study, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-naïve participants (aged ≥ 18years, without prior infection or vaccination against SARS-CoV-2) were randomized (1:1) to receive either S-268019-b or ChAdOx1 nCoV-19 as two intramuscular injections given 28days apart. Participants who provided consent for a booster administration received S-268019-b at Day 211. The primary endpoint was SARS-CoV-2 neutralizing antibody (NAb) titer on Day 57; the key secondary endpoint was the seroconversion rate for SARS-CoV-2 NAb titer on Day 57. Other endpoints included anti-SARS-CoV-2 S-protein immunoglobulin (Ig)G antibody titer and safety. The demographic and baseline characteristics were generally comparable between S-268019-b (n = 611) and ChAdOx1 nCoV-19 (n = 610) groups. S-268019-b showed superior immunogenicity over ChAdOx1 nCoV-19, based on their geometric mean titers (GMTs) and GMT ratios of SARS-CoV-2 NAb on Day 57 by cytopathic effect assay (GMT [95% confidence interval {CI}] 19.92 [18.68, 21.23] versus 3.63 [3.41, 3.87]; GMT ratio [95% CI] 5.48 [5.01, 6.00], respectively; two-sided p-values < 0.0001). Additionally, NAb measured using a cell viability assay also showed similar results (GMT [95% CI] 183.25 [168.04, 199.84] versus 24.79 [22.77, 27.00]; GMT ratio [95% CI] 7.39 [6.55, 8.35] for S-268019-b versus ChAdOx1 nCoV-19, respectively; p < 0.0001). The GMT of anti-SARS-CoV-2 S-protein IgG antibody was 370.05 for S-268019-b versus 77.92 for ChAdOx1 nCoV-19 on Day 57 (GMT ratio [95% CI] 4.75 [4.34, 5.20]). Notably, immune responses were durable through the end of the study. S-268019-b elicited T-helper 1 skewed T-cell response, comparable to that of ChAdOx1 nCoV-19. After the first dose, the incidence of solicited systemic treatment-related adverse events (TRAEs) was higher in the ChAdOx1 nCoV-19 group, but after the second dose, the incidence was higher in the S-268019-b group. Headache, fatigue, and myalgia were the most commonly reported solicited systemic TRAEs, while pain at the injection site was the most frequently reported solicited local TRAE following both doses in both groups. No serious treatment-related adverse serious TRAEs events were reported in the two groups. S-268019-b was more immunogenic than ChAdOx1 nCoV-19 vaccine and was well tolerated (jRCT2051210151).

Fulminant Vaccine-Induced Immune Thrombotic Thrombocytopenia after ChAdOx1 nCoV-19 (AZD1222) Vaccine Administration in a Woman with Obesity: A Case Report

Vaccine-induced immune thrombotic thrombocytopenia (VITT), also known as thrombosis with thrombocytopenia syndrome, is a rare complication of ChAdOx1 nCoV-19 (AZD1222) vaccine administration. The overall incidence of VITT worldwide is one case per 100 000 exposures. Because of the high mortality rate from VITT, thorough monitoring is crucial to predict the risk of occurrence. The underlying risk factors for VITT are not fully understood. Potential risk factors include sex (female) and young age (&lt;50 years), but further research must be conducted to confirm these assumptions. We report the case of a woman with obesity, which is a risk factor for deep vein thrombosis in the legs and for pulmonary embolism, who experienced fulminant VITT after AZD1222 vaccine administration.

The Safety of Covishield (ChAdOx1 nCoV-19) Vaccine after Three Doses Vaccination under Mass Vaccination Program of Government of India

The Safety of Covishield (ChAdOx1 nCoV-19) Vaccine after Three Doses Vaccination under Mass Vaccination Program of Government of India

The Safety Profile of Common COVID-19 Vaccines in Patients With Multiple Sclerosis.

Background and objective Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). In light of the COVID-19 pandemic that emerged in late 2019, the World Health Organization (WHO) has endorsed mass immunization to enhance the population's immunity against the virus. However, certain concerns have been raised about the safety of COVID-19 vaccines among patients with autoimmune disorders, including those with multiple sclerosis (MS). Further research is required to address these concerns and to gain deeper insights into the possible complications of COVID-19 vaccines among MS patients. This study aimed to assess the side effects of COVID-19 vaccines among MS patients. Methods An observational cross-sectional study was conducted between May and November 2023 at the National Guard Hospital, Jeddah, Saudi Arabia. All MS patients enrolled in our local registry system and providedphone numbers were included in the study. A total of 208 MS patients were surveyed via phone interviews, and data were collected regarding their demographics, MS history, COVID-19 history, SARS-CoV-2 vaccination status, and their exposure to disease-modifying therapies (DMTs). All results were analyzed using Stata software. Statistical significance was set at a CI of 95% and a p-value <0.05. Results In our cohort, 128 (61.5%) patients had received three doses of the COVID-19 vaccine, while 68 (32.7%) had received two doses; four patients (2.0%) had received only one dose, five (2.4%) had not received the vaccine, and the number of doses was unknown for the remaining three patients (1.4%). The BNT162b2 mRNA COVID-19 Vaccine from Pfizer-BioNTech was the most commonly administered (n=136 patients, 66.0%),followed byChAdOx1 nCoV-19 Vaccine from Oxford-AstraZeneca (n=47 patients, 22.8%), and mRNA-1273 SARS-CoV-2 Vaccine from Moderna (n=5 patients, 2.4%). Of note, 139 patients (69.5%) reported experiencing adverse events after receiving the vaccine, and the ChAdOx1 nCoV-19 Vaccine from Oxford-AstraZeneca was significantly associated with higher rates of side effects, in 87.8%of the patients. Conclusion A sizable proportion of MS patients experienced self-limiting side effects from exposure to the COVID-19 vaccine. The rates and incidence of side effects were similar to those encountered in the general population. None of the adverse effectsrecorded in our population of MS patients were serious or life-threatening. We recommend thatphysicians encourage patients with MS who have never received COVID-19 vaccinationto get promptly vaccinated as the risks of COVID-19 infectionfar outweigh the minor risks associated with COVID-19 vaccination.

Aggressive Vaccine-Induced Immune Thrombocytopenia and Thrombosis in a Young Woman with a Past Mild SARS-CoV-2 Infection

Vaccine- induced immune thrombocytopenia and thrombosis (VITT) is a rare adverse event occurring after immunization with adenoviral vector-based vaccines against SARS-CoV-2. This life-threatening condition is characterized by thrombocytopenia, systemic activation of coagulation, and anti-platelet factor 4 antibodies, often resulting in extensive venous thrombosis. Arterial thrombosis is less common and mainly affects the aorta, peripheral arteries, heart, and brain. Several cases of ischemic stroke have been reported in VITT patients, frequently being associated with large vessel occlusion (LVO). Here, we present a case of aggressive VITT in a 46-year-old woman with a past mild SARS-CoV-2 infection, who was admitted with a left-middle cerebral artery (MCA) territory stroke and thrombocytopenia eight days after her first dose of the ChAdOx1 nCoV-19 vaccine. The patient developed a diffuse arterial thrombosis with concomitant thrombotic events in the intrahepatic portal branches. The patient’s clinical condition worsened rapidly due to a significant enlargement of the ischemic cerebral lesion in the left hemisphere, cerebral herniation, and incipient hydrocephalus requiring decompressive neurosurgery with an unfavorable outcome. Our observations may be indicative of a stroke variant in VITT and highlight the diverse clinical manifestations of the syndrome.

Acute disseminated encephalomyelitis post-SARS-COV-2 vaccination with Chadox1 nCov-19 (AZD1222) – A rare case report

Background: Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the CNS, characterized by fulminant multifocal neurologic injury and distinct neuropathologic findings.&#x0D; Case Report: We report a case of a forty-nine-year-old female who presented with progressive weakness of right side of the body of one-week duration. Clinical, laboratory and radiological features favored demyelination. There was temporal association with taking SARS COV 2 vaccination (ChAdOx1 n cov -19 (AZD1222)). She was treated with a course of steroids and made a good recovery.&#x0D; Conclusion: To our knowledge this is a rare case of ADEM noticed after ChAdOx1 nCoV-19 vaccine (AZD1222).

Humoral and cellular immune response in patients of liver cirrhosis and immunocompetent recipient of ChAdOx1nCoV-19 Vaccine (Covishield)

Despite the effectiveness of COVID-19 vaccination in reducing the severity of the disease, the demand for booster is increasing in vulnerable populations like elderly and immunocompromised individuals especially with each new wave of COVID-19 in different countries. There is limited data on the sustained immunity against COVID-19 in patients with liver cirrhosis. The study was aimed to compare the T cell and humoral immune response after 1 year of ChAdOx1nCoV-19 Vaccine in patients with liver cirrhosis and healthy health care workers (HCW). This was a prospective observational study including 36 HCW, 19 liver cirrhosis patients and 10 unvaccinated individuals. Anti-SARS-CoV-2S antibody, neutralizing antibody and memory T cell subsets were evaluated by ELISA and flow cytometry, respectively, in all three groups after 1 year of initial vaccination. Compared to HCW and unvaccinated individuals, liver cirrhosis patients had significantly depleted T cells, although CD4:CD8 + T cell ratio was normal. Both cirrhotic patients and HCW developed memory T cell subset [effector memory RA (P = 0.141, P < 0.001), effector memory (P < 0.001, P < 0.001), central memory (P < 0.001, P < 0.01), stem cell memory (P = 0.009, P = 0.08) and naïve (P < 0.001, P = 0.02)] compared to unvaccinated unexposed individuals of CD4 + T and CD8 + T, respectively. However, among HCW and cirrhotic group no difference was noted on central memory and stem cell memory cells on T cells. Patients with liver cirrhosis developed comparable memory T cells after vaccination which can evoke sustainable immune response on reinfection. Therefore, additional vaccine doses may not be necessary for cirrhosis patients.

Reported side-effects following Oxford/AstraZeneca COVID-19 vaccine in the north-west province, Iran: A cross-sectional study.

While the vaccination was introduced as a promising tool to control the Coronavirus disease 2019 (COVID-19) pandemic, concerns about vaccine-related side effects had grown. Due to the widespread administration of the COVID-19 vaccine worldwide for the first time, it was necessary to evaluate the safety and potential side effects in recipients. This study aims to assess, the incidence of adverse effects following Oxford-AstraZeneca vaccination and identify their related factors. In this cross-sectional survey-based study, 453 volunteers participated, including 235 men and 218 women. The reported adverse reactions from recipients of the ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine were collected by using a questionnaire. The findings showed that the incidence of adverse reactions, such as neurological, systematic, gastrointestinal, respiratory, and local symptoms were significantly higher after the first dose compared to the second dose. Systematic symptoms were the most prevalent reported side effects after the first and second dose injection. The demographical study of participants showed that individuals aged 18-34 and females were more prone to present adverse events following vaccination. However, no significant relationship was found between the occurrence of side effects and the recipients' body mass index. Despite the life-saving role of vaccination against SARS-CoV-2, it may have some adverse reactions in recipients. The severity and frequency of side effects were different. So, they were dependent on several factors, including gender and age. Altogether, post-vaccination adverse reactions were mild and tolerable.

Cardiovascular Safety of COVID-19 Vaccination in Patients With Cancer: A Self-Controlled Case Series Study in Korea.

Cancer patients have an increased risk of cardiovascular outcomes and are susceptible to coronavirus disease 2019 (COVID-19) infection. We aimed to assess the cardiovascular safety of COVID-19 vaccination for cancer patients in South Korea. We conducted a self-controlled case series study using the K-COV-N cohort (2018-2021). Patients with cancer aged 12 years or older who experienced cardiovascular outcomes were identified. Cardiovascular outcomes were defined as myocardial infarction, stroke, venous thromboembolism (VTE), myocarditis, or pericarditis, and the risk period was 0-28 days after receiving each dose of COVID-19 vaccines. A conditional Poisson regression model was used to calculate the incidence rate ratio (IRR) with 95% confidence interval (CI). Among 318,105 patients with cancer, 4,754 patients with cardiovascular outcomes were included. The overall cardiovascular risk was not increased (adjusted IRR, 0.99 [95% CI, 0.90-1.08]) during the whole risk period. The adjusted IRRs of total cardiovascular outcomes during the whole risk period according to the vaccine type were 1.07 (95% CI, 0.95-1.21) in the mRNA vaccine subgroup, 0.99 (95% CI, 0.83-1.19) in the ChAdOx1 nCoV-19 vaccine subgroup, and 0.86 (95% CI, 0.68-1.10) in the mix-matched vaccination subgroup. However, in the analysis of individual outcome, the adjusted IRR of myocarditis was increased to 11.71 (95% CI, 5.88-23.35) during the whole risk period. In contrast, no increased risk was observed for other outcomes, such as myocardial infarction, stroke, VTE, and pericarditis. For cancer patients, COVID-19 vaccination demonstrated an overall safe profile in terms of cardiovascular outcomes. However, caution is required as an increased risk of myocarditis following COVID-19 vaccination was observed in this study.

Adverse events following immunization of ChAdOx1 nCoV-19 vaccine among healthcare workers of a medicine-teaching institution of North India.

This study sought to assess the prevalence of adverse events following immunization (AEFI) and factors associated with AEFI of the ChAdOx1 nCoV-19 vaccine (Covishield) among healthcare workers (HCW) of a medicine-teaching institution of North India. A cross-sectional study was conducted in the months of June and July 2021 among HCW (N = 203) of 18 years and above, vaccinated with at least the first dose of Covishield. A semi-structured, prevalidated, and pretested questionnaire was used to collect information through an interview schedule. The questionnaire was divided into five sections: the sociodemographic profile, behavioral characteristics, past medical history, COVID-19 awareness, and past infection and COVID-19 vaccine related information. Chi-squared test was applied to check the association of different factors with AEFI. In our study, 73.89% of participants suffered from at least one AEFI after the first dose of the vaccine, while 48.66% had at least one AEFI after the second dose. Females reported significantly high AEFI for both doses (P = 0.001, 0.000). We found a significant association between the occurrence of AEFI and occupation (first dose P = 0.015), substance abuse (first dose P = 0.002), diet (first dose P = 0.016), and allergy (first dose P = 0.027). Other significant findings were headaches among HCW ≥40 years of age (dose P = 0.034) and systemic AEFI in participants with comorbidity (first dose P = 0.020). More AEFI were reported after the first dose as compared to the second dose. AEFI were more among females after both the doses. Occupation, substance use, diet, and history of allergy were significantly associated with AEFI.

Safety and immunogenicity of ChAdOx1 nCoV-19 (AZD1222) vaccine in adults in Kenya: a phase 1/2 single-blind, randomised controlled trial.

There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vaccine performance in different geographical settings to inform Emergency Use Authorisation. We recruited and randomly assigned (1:1) 400 healthy adults aged ≥18 years in Kenya to receive ChAdOx1 nCoV-19 or control rabies vaccine, each as a two-dose schedule with a 3-month interval. The co-primary outcomes were safety, and immunogenicity assessed using total IgG enzyme-linked immunosorbent assay (ELISA) against SARS-CoV-2 spike protein 28 days after the second vaccination. Between 28 th October 2020 and 19 th August 2021, 400 participants were enrolled and assigned to receive ChAdOx1 nCoV-19 (n=200) or rabies vaccine (n=200). Local and systemic adverse events were self-limiting and mild or moderate in nature. Three serious adverse events were reported but these were deemed unrelated to vaccination. The geometric mean anti-spike IgG titres 28 days after second dose vaccination were higher in the ChAdOx1 group (2773 ELISA units [EU], 95% CI 2447, 3142) than in the rabies vaccine group (61 EU, 95% CI 45, 81) and persisted over the 12 months follow-up. We did not identify any symptomatic infections or hospital admissions with respiratory illness and so vaccine efficacy against clinically apparent infection could not be measured. Vaccine efficacy against asymptomatic SARS-CoV-2 infection was 38.4% (95% CI -26.8%, 70.1%; p=0.188). The safety, immunogenicity and efficacy against asymptomatic infection of ChAdOx1 nCoV-19 among Kenyan adults was similar to that observed elsewhere in the world, but efficacy against symptomatic infection or severe disease could not be measured in this cohort. PACTR202005681895696 (11/05/2020).

Modeling vaccination strategies with limited early COVID-19 vaccine access in low- and middle-income countries: A case study of Thailand

Low- and middle-income countries faced significant challenges in accessing COVID-19 vaccines during the early stages of the pandemic. In this study, we utilized an age-structured modeling approach to examine the implications of various vaccination strategies, vaccine prioritization, and vaccine rollout speeds in Thailand, an upper-middle-income country experiencing vaccine shortages during the early stages of the pandemic. The model directly compares the effectiveness of several vaccination strategies, including the heterologous vaccination where CoronaVac (CV) vaccine was administered as the first dose, followed by ChAdOx1 nCoV-19 (AZ) vaccine as the second dose, under varying disease transmission dynamics. We found that the traditional AZ homologous vaccination was more effective than the CV homologous vaccination, regardless of disease transmission dynamics. However, combining CV and AZ vaccines via either parallel homologous or heterologous vaccinations was more effective than relying solely on AZ homologous vaccination. Additionally, prioritizing vaccination for the elderly aged 60 years and above was the most effective way to reduce mortality when community transmission is well-controlled. On the other hand, prioritizing workers aged 20–59 was most effective in lowering COVID-19 cases, irrespective of the transmission dynamics. Lastly, despite the vaccine prioritization strategy, rapid vaccine rollout speeds were crucial in reducing COVID-19 infections and deaths. These findings suggested that in low- and middle-income countries where early access to high-efficacy vaccines might be limited, obtaining any accessible vaccines as early as possible and using them in parallel with other higher-efficacy vaccines might be a better strategy than waiting for and relying solely on higher-efficacy vaccines.

Epidemiological Characteristics of COVID-19 during Seven Consecutive Epidemiological Waves (2020-2022) in the North Bačka District, Serbia.

The COVID-19 pandemic continues to pose a threat to global public health. The purpose of this research was to determine the epidemiological characteristics of COVID-19 in the North Bačka district while observing seven pandemic waves. The cross-sectional study was based on data from the COVID-19 surveillance database of the Institute for Public Health of Vojvodina during the period from March 2020 to December 2022. A total of 38,685 primary infections and 4067 reinfections caused by SARS-CoV-2 were notified. Pandemic waves caused by the Delta variant (cumulative incidence rate of 2482.37/100,000) and by the Omicron variant (cumulative incidence rate of 2994.45/100,000) emerged as significant focal points during the surveillance period. Over the course of three consecutive years (2020-2022), women were more affected (50.11%, 54.03%, and 55.68%, respectively). The highest incidence rates in age-specific categories were recorded in 2021 for the age group 40-49 (1345.32 per 10,000 inhabitants), while in 2022, they shifted towards the elderly population. Regarding vaccination status at the time of diagnosis, in 2021, around 15% of patients were vaccinated, while in 2022, the number increased to 37%. The most widely received vaccine was BBIBP-CorV (67.45%), followed by BNT162b2 (19.81%), Gam-COVID-Vac (9.31%), and ChAdOx1 nCoV-19 (3.42%) vaccine. The implementation of stringent public health measures and their mitigation, together with the emergence of new variants, influenced the dynamics of COVID-19 pandemic waves in the North Bačka district. Notably, throughout the study period, the working-age population was the most affected, along with females, with a mild clinical presentation dominating. Reinfections were most frequently recorded during the latter pandemic waves. Dealing with this pandemic has provided some valuable lessons for the development of future strategies in the case of a similar public health crisis.