ChAdOx1 nCoV-19 Vaccine Research Articles

Postmortem PF4 antibodies confirm a rare case of thrombosis thrombocytopenia syndrome associated with ChAdOx1 nCoV-19 anti-COVID vaccination.

We report a case of cerebral venous sinus thrombosis, bilateral adrenal hemorrhage, and thrombocytopenia in a 70-year-old man found dead. He had previously received the ChAdOx1 nCoV-19 vaccine (Vaxzevria®, AstraZeneca) 18 days before, and had since developed unspecific and undiagnosed characteristics of what proved to be a rare case of vaccine-associated thrombocytopenia with thrombosis syndrome (TTS). He was found dead 1 week after the beginning of symptoms (day 25 post-vaccine). Autopsy yielded venous hemorrhagic infarction with the presence of thrombi within dural venous sinuses, and extensive hemorrhagic necrosis of the central part of the adrenal glands. Antibodies against platelet factor 4 (PF4) were strongly positive in postmortem fluids, as measured with an enzyme-linked immunosorbent assay (ELISA). This difficult diagnosis is usually made during the patient’s lifetime. After eliminating differential diagnoses, we concluded on a fatal case of vaccine-induced immune TTS with positive anti-PF4 antibodies in cadaveric blood, 3 weeks after ChAdOx1 nCoV-19 vaccination. Specific search for anti-PF4 antibodies in cadaveric blood appears therefore paramount to assess postmortem cases of TTS associated with anti-COVID vaccines.

Central retinal vein occlusion post ChAdOx1 nCoV-19 vaccination – can it be explained by the two-hit hypothesis?

PurposeTo report a case of central retinal vein occlusion (CRVO) seven days following the first dose of ChAdOx1 nCoV-19 vaccine and propose a hypothesis for the possible underlying pathogenesis.ObservationA 31-year-old male presented with CRVO with cystoid macular edema, one week after receiving his first ChAdOx1 nCoV-19 vaccine dose. Apart from mild hyperhomocysteinemia, no major thrombophilic or systemic risk factors were found. Anti-platelet factor 4 antibodies, specific for vaccine-induced immune thrombotic thrombocytopenia, were also negative. However, he tested strongly positive (> 250 U/mL) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG spike antibodies, 2 weeks post the first dose – suggestive of a prior subclinical infection.ConclusionCOVID-19 is known to be associated with an altered host one-carbon metabolism resulting in hyperhomocysteinemia. We hypothesize that a prior subclinical infection with COVID-19, the first hit, may have led to hyperhomocysteinemia in our patient and vaccination must have been the second hit that triggered the thrombotic event. Further studies, including correlation of thrombotic complications with IgG antibody titres post-vaccination, are essential in order to better understand the pathogenesis of such events.

Associations of neuralgic amyotrophy with COVID-19 vaccination: Disproportionality analysis using the World Health Organization pharmacovigilance database.

There are limited studies on the association of COVID-19 vaccination with neuralgic amyotrophy (NA). Therefore, we evaluated the association between COVID-19 vaccination and the occurrence of NA. We explored unexpected safety signals for NA related to COVID-19 vaccination through disproportionality analysis using VigiBase, the World Health Organization's pharmacovigilance database. On October 15, 2021, 335 cases of NA were identified in the database. The median time to onset of NA after vaccination was around 2 weeks. A significant signal of disproportionality of NA was observed for the ChAdOx1 nCoV-19 vaccine (AstraZeneca) (information component [IC]025 =0.33, reporting odds ratio [ROR]025 =1.30) and two mRNA-based COVID-19 vaccines (BNT162b2 [Pfizer and BioNTech] and mRNA-1273 [Moderna]) (IC025 =1.74, ROR025 =3.82) compared with the entire database. However, when compared with influenza vaccines, we did not detect any signal of disproportionality of NA for both the ChAdOx1 nCoV-19 vaccine (IC025 =-2.71, ROR025 =0.05) and mRNA-based COVID-19 vaccines (IC025 =-1.38, ROR025 =0.13). A weak association was observed between NA and COVID-19 vaccines. However, the risk did not surpass that of influenza vaccines.

Durability of ChAdOx1 nCoV-19 (AZD1222) vaccine and hybrid humoral immunity against variants including omicron BA.1 and BA.4 6 months after vaccination (COV005): a post-hoc analysis of a randomised, phase 1b–2a trial

BackgroundCOVID-19 vaccine rollout is lagging in Africa, where there has been a high rate of SARS-CoV-2 infection. We aimed to evaluate the effect of SARS-CoV-2 infection before vaccination with the ChAdOx-nCoV19 (AZD1222) vaccine on antibody responses through to 180 days.MethodsWe did an unmasked post-hoc immunogenicity analysis after the first and second doses of AZD1222 in a randomised, placebo-controlled, phase 1b–2a study done in seven locations in South Africa. AZD1222 recipients who were HIV-uninfected, were stratified into baseline seropositive or seronegative groups using the serum anti-nucleocapsid (anti-N) immunoglobulin G (IgG) electroluminescence immunoassay to establish SARS-CoV-2 infection before the first dose of AZD1222. Binding IgG to spike (anti-S) and receptor binding domain (anti-RBD) were measured before the first dose (day 0), second dose (day 28), day 42, and day 180. Neutralising antibody (NAb) against SARS-CoV-2 variants D614G, beta, delta, gamma, and A.VOI.V2, and omicron BA1 and BA.4 variants, were measured by pseudovirus assay (day 28, day 42, and day 180). This trial is registered with ClinicalTrials.gov, NCT04444674, and the Pan African Clinicals Trials Registry, PACTR202006922165132.FindingsOf 185 individuals who were randomly assigned to AZD1222, we included 91 individuals who were baseline seropositive and 58 who were baseline seronegative, in the final analysis. In the seropositive group, there was little change of anti-S IgG (and anti-RBD IgG) or neutralising antibody (NAb) titres at day 42 compared with at day 28. Anti-S (and anti-RBD) IgG geometric mean concentrations (GMCs) were higher throughout in the seropositive compared with the seronegative group, including at day 180 (GMCs 517·8 [95% CI 411·3–651·9] vs 82·1 [55·2–122·3] BAU/mL). Also D614G NAb geometric mean titres (GMTs) were higher in the seropositive group than the seronegative group, as was the percentage with titres of at least 185 (80% putative risk reduction threshold [PRRT] against wild-type–alpha COVID-19), including at day 180 (92·0% [74·0–99·0] vs 18·2% [2·3–51·8). Similar findings were observed for beta, A.VOI.V2, and gamma. For delta, BA.1, and BA.4, NAb GMTs and the proportion with titres above the PRRT were substantially higher in the seropositive compared with seronegative group at day 28 and day 42, but no longer differed between the groups by day 180.InterpretationA single dose of AZD1222 in the general African population, where COVID-19 vaccine coverage is low and SARS-CoV-2 seropositivity is 90%, could enhance the magnitude and quality of antibody responses to SARS-CoV-2.FundingThe Bill & Melinda Gates Foundation, the South African Medical Research Council, the UK Research and Innovation, the UK National Institute for Health Research, and the South African Medical Research Council.TranslationFor the Zulu translation of the abstract see Supplementary Materials section.

Follow-up and evolution of a patient with COVID-19 and severe ARDS: case report

A 42-year-old patient, a physician, with a history of high blood pressure and essential tremor, who received a dose of ChAdOx1 nCoV-19 vaccine (AZD1222). It began with symptoms compatible with COVID-19 and evolved unfavorably, developing Severe Respiratory Distress Syndrome. He was admitted to Intensive Care Unit requiring mechanical respiratory assistance, sedation, neuromuscular blockers and prone position. He evolved favorably so he was placed in the supine position 24 hours a day and managed to be extubated on the third day. On the 13th day of hospitalization, he was discharged from the hospital. One month later, pulmonary rehabilitation begins on an outpatient basis. A self-administered quality of life questionnaire (RAND36) was taken, where all spheres, mainly physical and emotional, were found to be affected, achieving improvement in each of them 4 weeks after rehabilitation. Functionality was evaluated through the Sit to Stand 1 minute and the Time Up and Go where favorable results were also obtained at 4 weeks.

Human leukocyte antigen alleles associate with COVID-19 vaccine immunogenicity and risk of breakthrough infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine immunogenicity varies between individuals, and immune responses correlate with vaccine efficacy. Using data from 1,076 participants enrolled in ChAdOx1 nCov-19 vaccine efficacy trials in the United Kingdom, we found that inter-individual variation in normalized antibody responses against SARS-CoV-2 spike and its receptor-binding domain (RBD) at 28 days after first vaccination shows genome-wide significant association with major histocompatibility complex (MHC) class II alleles. The most statistically significant association with higher levels of anti-RBD antibody was HLA-DQB1*06 (P = 3.2 × 10−9), which we replicated in 1,677 additional vaccinees. Individuals carrying HLA-DQB1*06 alleles were less likely to experience PCR-confirmed breakthrough infection during the ancestral SARS-CoV-2 virus and subsequent Alpha variant waves compared to non-carriers (hazard ratio = 0.63, 0.42–0.93, P = 0.02). We identified a distinct spike-derived peptide that is predicted to bind differentially to HLA-DQB1*06 compared to other similar alleles, and we found evidence of increased spike-specific memory B cell responses in HLA-DQB1*06 carriers at 84 days after first vaccination. Our results demonstrate association of HLA type with Coronavirus Disease 2019 (COVID-19) vaccine antibody response and risk of breakthrough infection, with implications for future vaccine design and implementation.

Maintenance of Antibody Response in Egyptian Healthcare Workers Vaccinated with ChAdOx1 nCoV-19 Vaccine during Delta and Omicron Variants Pandemic: A Prospective Study.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a constantly evolving virus, resulting in an increased burden on the existing COVID-19 vaccines. Healthcare workers (HCWs) are the first line of defense against the coronavirus disease 2019 (COVID-19) pandemic and have been prioritized among the risk categories receiving the COVID-19 vaccine. This work aimed to investigate the maintenance of antibody response of the Oxford–AstraZeneca vaccine (ChAdOx1/nCoV-19). Methods: Anti-spike immunoglobulin G (IgG) was measured at baseline point (immediately prior to vaccination) and 12- and 24-week (w) points following vaccination. Adverse reactions to the vaccine were reported. Participants were followed up for the incidence of COVID-19 during the 12 w interval between vaccination doses for 24 w after the second dose. Results: A total of 255 HCWs participated in the study. Prior to vaccination, 54.1% experienced COVID-19, 88.2% were seropositive after the first dose, while seropositivity reached 95.7% after the second dose. Following the first and second doses, the anti-spike IgG serum level was significantly higher in subjects with past COVID-19 than in others (p < 0.001 and =0.001, respectively). Conclusions: The Oxford–AstraZeneca vaccine is generally safe and provides a highly effective long-term humoral immune response against the Delta and Omicron variants of SARS-CoV-2.

Determinants of COVID-19 Breakthrough Infections and Severity in ChAdOx1 nCoV-19-Vaccinated Priority Groups.

The current analysis is a part of an ongoing observational study that began in February 2021 in the Sir Sunder Lal Hospital (Varanasi, Uttar Pradesh) in northern India and is expected to continue until June 2022. This analysis aimed to delineate the clinical presentation and risk factors of occurrence and severity of COVID-19 in vaccinated individuals. The study enrolled health-care workers and the elderly receiving the COVID-19 vaccine at one of three centers linked to the study hospital. The participants received the ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine based on the chimpanzee adenovirus platform (manufactured in India by the Serum Institute of India). The adenovirus codes for the spike (S) protein of SARS-CoV-2. Participants were contacted by phone at pre-decided intervals and questioned about the occurrence of COVID-19, clinical presentation, severity, and persistence of symptoms. A logistic regression analysis was performed to predict the risk factors of occurrence and severity of COVID-19. Of the 1,500 participants included in the analysis, 418 developed COVID-19 (27.9%). Fever was the most common symptom (72%), followed by cough (34%) and rhinitis (26%). Cardiovascular involvement was seen in more than 2% of individuals, and 11% had post-COVID-19 complaints. Regression analysis showed 1.6 times greater odds of contracting the disease in females and in those younger than 40 years, 1.4 times greater odds in individuals who were overweight, and 2.9 times greater odds in those receiving only one dose, compared with respective comparators. Individuals receiving two doses at a gap of ≤ 30 days had 6.7 times greater odds of infection than those receiving at a > 60-day interval. There was no association between COVID-19 occurrence in the vaccinees and pre-vaccination history of SARS-CoV-2 infection. Males were at a 3.6 times greater risk, and persons with preexisting lung disease-mainly asthma-had a 5.9 times greater risk of experiencing moderate to severe COVID-19 than comparators. While an extended interval between the two vaccine doses seems to be a better strategy, gender differences and an association of asthma phenotypes with COVID-19 need to be explored.

Antibody Response to ChAdOx1 nCoV-19 (AZD1222) Vaccine in Kidney Transplant Recipients.

Kidney transplant recipients (KTRs) are at a much higher risk of complications and death following COVID-19 and are poor vaccine responders. The data are limited on the immune response to Covishield® in KTRs. We prospectively recruited a cohort of 67 KTRs aged >18 between April 2021 and December 2021. Each participant was given two intramuscular doses of Covishield®, each of 0.5 mL, at an interval of 12 weeks. A blood specimen of 5.0 mL was collected from each participant at two points within a few days before administering the first dose of the vaccine and at any time between 4–12 weeks after administering the second dose. The sera were tested for anti-RBD antibody (ARAb) titre and neutralising antibody (NAb). An ACE2 competition assay was used as a proxy for virus neutralization. According to the prior COVID-19 infection, participants were grouped as (i) group A: prior symptomatic COVID-19 infection, (ii) group B: prior asymptomatic COVID-19 infection as evidenced by detectable ARAb in the prevaccination specimen, (iii) Group C: no prior infection with COVID-19, (iv) group D: Unclassified, i.e., participants had no symptoms suggestive of COVID-19, but their prevaccination specimen was not available for ARAb testing before vaccination. Fifty of sixty-seven participants (74.6%) provided paired specimens (group A 14, group B 27, and group C 9) and 17 participants (25.4%) provided only postvaccination specimens (group D). In the overall cohort (n = 67), 91% and 77.6% of participants developed ARAb and NAb, respectively. Their ARAb titre and NAb proportion were 2927 (520–7124) U/mL and 87.9 (24.4–93.2) %, respectively. Their median ARAb titre increased 65.6 folds, from 38.2 U/mL to 3137 U/mL. Similarly, the proportion of participants with NAb increased from 56% to 86%, and the NAb proportion raised 2.7 folds, from 23% to 91%. A comparison of vaccine response between the study groups showed that all those with or without prior COVID-19 infection showed a significant rise in ARAb titre (p < 0.05) and NAb proportion (p < 0.05) after the two doses of vaccine administration. The median value of folds rise in anti-RBD and NAb between groups A and B were comparable. Hence, ARAb is present in more than 3/4th of KTRs before the ChAdOx1 vaccine in India. The titer of ARAb and the proportion of NAb significantly increased after the two doses of the ChAdOx1 vaccine in KTRs.

Association Between Vaccination Status and Mortality Among Intubated Patients With COVID-19–Related Acute Respiratory Distress Syndrome

Although vaccination substantially reduces the risk of severe COVID-19, it is yet unknown whether vaccinated patients who develop COVID-19 and require invasive mechanical ventilation have lower mortality than controls. To examine the association between COVID-19 vaccination status and mortality among critically ill patients who require invasive mechanical ventilation owing to acute respiratory distress syndrome (ARDS) related to COVID-19. This multicenter cohort study was performed between June 7, 2021, and February 1, 2022, among 265 consecutive adult patients with COVID-19 in academic intensive care units who underwent invasive mechanical ventilation owing to ARDS. Patients in the full vaccination group had completed the primary COVID-19 vaccination series more than 14 days but less than 5 months prior to intubation. This time threshold was chosen because guidelines from the US Centers for Disease Control and Prevention recommend a booster dose beyond that time. The remaining patients (ie, those who were unvaccinated, partially vaccinated, or fully vaccinated <14 days or >5 months before intubation) comprised the control group. The primary outcome was time from intubation to all-cause intensive care unit mortality. A Cox proportional hazards regression model including vaccination status, age, comorbid conditions, and baseline Sequential Organ Failure Assessment score on the day of intubation was used. A total of 265 intubated patients (170 men [64.2%]; median age, 66.0 years [IQR, 58.0-76.0 years]; 26 [9.8%] in the full vaccination group) were included in the study. A total of 20 patients (76.9%) in the full vaccination group received the BNT162b2 vaccine, and the remaining 6 (23.1%) received the ChAdOx1 nCoV-19 vaccine. Patients in the full vaccination group were older (median age, 72.5 years [IQR, 62.8-80.0 years] vs 66.0 years [IQR, 57.0-75.0 years]) and more likely to have comorbid conditions (24 of 26 [92.3%] vs 160 of 239 [66.9%]), including malignant neoplasm (6 of 26 [23.1%] vs 18 of 239 [7.5%]), than those in the control group. Full vaccination status was significantly associated with lower mortality compared with controls (16 of 26 patients [61.5%] died in the full vaccination group vs 163 of 239 [68.2%] in the control group; hazard ratio, 0.55 [95% CI, 0.32-0.94]; P = .03). In this cohort study, full vaccination status was associated with lower mortality compared with controls, which suggests that vaccination might be beneficial even among patients who were intubated owing to COVID-19-related ARDS. These results may inform discussions with families about prognosis.

Durability of Immune Response to ChAdOx1-nCoV-19 Vaccine in Solid Cancer Patients Undergoing Anticancer Treatment.

There are limited data available about the durability of the immune response after administration of the widely used adenovirus-vectored ChAdOx1-nCoV-19 vaccine in cancer patients. This prospective longitudinal observational study analyzed follow-up data of immunogenic responses 12 weeks after the second dose of the ChAdOx1-nCoV-19 vaccine in 290 oncological patients compared to healthy controls. The study aimed to assess the persistence of the humoral immune response three months after the second dose, and omicron neutralization was also evaluated. Three months after completion of the second vaccine dose, the geometric mean titer of SARS-CoV-2 binding total Ig statistically decreased by 42% compared to those at 4 weeks, and was lower than that of the healthy control. Six percent of patients became seronegative for anti-RBD total Ig. Only 5% (2 of 40 samples) tested positive for surrogate neutralization against SAR-CoV-2 Omicron BA.2. Across different therapy types, a waning in immunogenicity was observed within three months after the second dose of the ChAdOx1 nCoV-19 vaccine, rendering it insufficient at that point to protect against the SAR-CoV-2 Omicron BA.2 variant.

Sequential Observation of Antibody Response Pattern at 3 and 6 Months Following ChAdOx1 nCoV-19 Vaccination Among Health Care Workers-A Prospective Single Cohort Study

Background: The duration of the immune response induced by ChAdOx1 nCoV-19 vaccination in a real-world setting is unknown. Objectives: This study is aimed to estimate the 6-month trend of SARS-CoV-2 antibody titer after Covishield vaccination among Health Care workers (HCW) and their associated factors. Materials &amp; Methods: A prospective single cohort study of health care workers was done in a tertiary care-teaching institute of central Kerala from January 2021 to October 2021. HCWs who have given pre-vaccination serum sample for SARS-CoV-2 antibody estimation and negative for SARS-CoV-2 antibody were included. They were followed up and their blood samples to check for antibody levels were taken 28 days after first dose, 2 weeks after second dose, and 3 and 6 months after first dose of ChAdOx1 nCoV-19 vaccine. Samples taken from 102 HCW were sent for SARS-CoV-2 IgG antibody testing. Results: Mean age of the study participants was 39.3 (age range:19 - 71) yrs. and 71.6% were females. Antibody levels of participants at 3rd month ranged from 0.28 S/C to 21.2 S/C with a mean of 8.01. Only 34 (33.3%) HCW had IgG antibody levels &gt;9.5 S/C. Mean antibody level further declined to 6.09 S/C at 6th month. Only 19 (28.4%) had antibody levels more than 9.5 S/C at 6th month. HCW with aged less than 50 years and those who had COVID disease during the study period had a significantly higher level of IgG antibody titres. Quantitative results were reported as signal to cut-off (S/C) value. Conclusion: The study found that after vaccination with Covishield vaccine IgG levels peaked at 14 days following second dose of vaccine, then getting decreased in the third month and further in sixth month confirming the need for a booster dose. COVID antibody levels were significantly higher in COVID infected HCW and in young age participants

VACCINE-INDUCED IMMUNE THROMBOTIC THROMBOCYTOPENIA (VITT) BY A THIRD DOSE OF CHADOX1 NCOV-19 (ASTRAZENECA) AFTER BNT162B2 (PFIZER–BIONTECH)

An atypical case of VITT was described resulting from a vaccination schedule where the third booster with ChAdOx1 nCoV-19 (AstraZeneca) was administered. The patient received a complete vaccination schedule with two doses of Pfizer-BioNTech (BNT162b2) without any complications before the third dose. However, the patient has developed an infrequent yet extreme prothrombotic; hypercoagulable state caused by platelet-activating anti-Platelet Factor 4 (PF4) antibodies. This phenomenon is typically triggered by the proximate administration of an adenoviral vector vaccine against COVID-19. The patient's symptoms began ten days after taking the third dose of the ChAdOx1 nCoV-19 vaccine (AstraZeneca). His main complaints when hospitalized were severe headaches and right abdominal pain. The blood tests and MRI scan imaging findings were very characteristic of VITT, and a rare cerebral venous sinus thrombosis was found. Also, a markedly elevated D-dimer and strong positive PF4-dependent enzyme-immunoassay test results were documented. Due to discerning clinical suspicion, this patient was rapidly treated with immunoglobulin infusion for two days and oral steroids for three days. Subsequently, he was anticoagulated with the new oral anticoagulant edoxaban after platelet numbers recovery. In a few days, platelets normalized, and D-dimer levels decreased, while anti- PF4-dependent enzyme-immunoassay test results showed a slow decline. He was discharged taking oral edoxaban without any sequeal.

Immune Response to SARS-CoV-2 Third Vaccine in Patients With Rheumatoid Arthritis Who Had No Seroconversion After Primary 2-Dose Regimen With Inactivated or Vector-Based Vaccines.

The aim of this study was to assess the immune response after a third dose of SARS-CoV-2 vaccine in patients with rheumatoid arthritis (RA) with undetectable antibody titers after the primary regimen of 2 doses. Patients with RA with no seroconversion after 2 doses of SARS-CoV-2 vaccine and who received a third dose of either an mRNA or vector-based vaccine were included. Anti-SARS-CoV-2 IgG antibodies, neutralizing activity, and T cell responses were assessed after the third dose. A total of 21 nonresponder patients were included. At the time of vaccination, 29% were receiving glucocorticoids and 85% biologic disease-modifying antirheumatic drugs (including 6 taking abatacept [ABA] and 4 taking rituximab [RTX]). The majority (95%) received the BNT162b2 vaccine and only one of them received the ChAdOx1 nCoV-19 vaccine. After the third dose, 91% of the patients presented detectable anti-SARS-CoV-2 IgG and 76% showed neutralizing activity. Compared to other treatments, ABA and RTX were associated with the absence of neutralizing activity in 4 out of 5 (80%) patients and lower titers of neutralizing antibodies (median 3, IQR 0-20 vs 8, IQR 4-128; P = 0.20). Specific T cell response was detected in 41% of all patients after the second dose, increasing to 71% after the third dose. The use of ABA was associated with a lower frequency of T cell response (33% vs 87%, P = 0.03). In this RA cohort, 91% of patients who failed to seroconvert after 2 doses of SARS-CoV-2 vaccine presented detectable anti-SARS-CoV-2 IgG after a third dose. The use of ABA was associated with a lower frequency of specific T cell response.

Effect of Inactivated SARS-CoV-2 Vaccines and ChAdOx1 nCoV-19 Vaccination to Prevent COVID-19 in Thai Households (VacPrevent trial)

ObjectivesSARS-CoV-2 is primarily transmitted within households, with massive healthcare system burdens. The role of inactivated vaccines and ChAdOx1 nCoV-19 vaccination in the prevention of within-household transmission remains unknown.MethodsThis observational case-control study tracked 408 SARS-CoV-2 polymerase chain reaction–confirmed index cases from April to September 2021. This study aimed to prove the benefit of inactivated and ChAdOx1 nCoV-19 vaccinated index cases in preventing within-household transmissibility.ResultsA total of 1178 household contacts were investigated. A total of 231 index cases were vaccinated with inactivated or ChAdOx1 nCoV-19 vaccine, and 177 were unvaccinated. The vaccinated index cases exhibited a 7.8% risk reduction in household transmission. There was no difference in the secondary attack rate of 50.77% in unvaccinated cases compared with 46.81% in vaccinated index cases (P-value = 0.177). Those who completed the two-dose SARS-CoV-2 vaccination demonstrated a 93% reduction in household transmissibility within 14-90 days. The effectiveness for preventing household transmission was 26.09%. The 87% reduced risk of household transmissibility was observed among those who wore masks.ConclusionThe completed two-dose SARS-CoV-2 inactivated and ChAdOx1 nCoV-19 vaccination within 14-90 days among index cases demonstrated benefits in preventing within-household transmissibility. Implementing high-efficacy vaccination and an appropriate booster dose can prevent household transmission.

Immune response after COVID-19 vaccination among patients with chronic kidney disease and kidney transplant

BackgroundVaccination of patients with chronic kidney disease (CKD) and kidney transplants (KTs) may achieve a less robust immune response. Understanding such immune responses is crucial for guiding current and future vaccine dosing strategies. MethodsThis prospective, observational study estimated the immunogenicity of humoral and cellular responses of two SARS-CoV-2 vaccines in different patient groups with CKD compared with controls. Secondary outcomes included adverse events after vaccination and the incidence of COVID-19 breakthrough infection, including illness severity. ResultsIn total, 212 patients received ChAdOx1 nCoV-19 (89.62 %) or inactivated vaccines (10.38 %).The antibody response against the S protein was analyzed at T0 (before the first injection), T1 (before the second injection), and T2 (12 weeks after the second injection). Seroconversion occurred in 92.31 % of controls at T2 and in 100 % of patients with CKD, 42.86 % undergoing KT, 80.18 % of hemodialysis (HD), and 0 % of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) at T2 of the ChAdOx1 nCoV-19 vaccine. Neutralizing antibody levels by surrogate virus neutralization test were above the protective level at T2 in each group. The KT group exhibited the lowest neutralizing antibody and T cell response. Blood groups O and vaccine type were associated with good immunological responses. After the first dose, 14 individuals (6.6 out of the total population experienced COVID-19 breakthrough infection. ConclusionImmunity among patients with CKD and HD after vaccination was strong and comparable with that of healthy controls. Our study suggested that a single dose of the vaccine is not efficacious and delays may result in breakthrough infection. Some blood groups and types of vaccine can affect the immune response.

A study on seroconversion following first & second doses of ChAdOx1 nCoV-19 vaccine in Central Kerala.

Vaccination against COVID-19 induces spike protein-binding IgG antibodies, a robust correlate of protection against COVID-19. This study was undertaken to assess the humoral response after completion of both the doses of ChAdOx1 nCoV vaccine in healthcare workers (HCWs) at a tertiary care health centre in India. A cross-sectional COVID-19 vaccine-induced antibody study was conducted among HCWs. IgG antibodies against spike protein were measured at least 28 days after the first dose and the second dose of vaccination in both SARS CoV-2 naïve and recovered HCWs. Mean and median antibody titre following each dose of vaccine and its association with age, gender, co-morbidities and factors such as exercise, stress and sleep deprivation were also explored. Among the 200 vaccine recipients, 91.5 per cent showed seroconversion after the first dose and 99.5 per cent after the second dose. The mean titre after the second dose was significantly higher when compared to the first dose (12.68±4.17 vs. 9.83±6.3, P=0.001). More than half (54%) had high antibody titre ≥12 S/Co (Signal/cut-off). Previous COVID-19 infection was the single most important factor influencing antibody production, where the mean titre just after a single dose [mean-17.81±5.94, median-20.5 (interquartile range [IQR]-3.7)] surpassed the titre after the second dose in SARS CoV-2 naïve individuals [mean-12.29±4.00, median-12.8 (IQR-3.7), P=0.001]. Furthermore, 28 per cent of vaccinees showed a reduction in titre after the second dose. The mean fall in titre was 2.25±1.40 and was more pronounced in males, the younger age group and those with previous COVID-19 infection. ChAdOx1 nCov-19 vaccine after two doses elicited an excellent immune response. However, greater immunogenicity after the first dose was seen among those with previous COVID-19 infection, even surpassing the titre achieved by the second dose of vaccine in SARS CoV-2 naïve recipients. A fall in antibody titre after the second dose is a matter of concern and requires further studies.

A randomized controlled trial of heterologous ChAdOx1 nCoV-19 and recombinant subunit vaccine MVC-COV1901 against COVID-19

Heterologous prime-boost COVID-19 vaccine strategy may facilitate mass COVID-19 immunization. We reported early immunogenicity and safety outcomes of heterologous immunization with a viral vector vaccine (ChAdOx1) and a spike-2P subunit vaccine (MVC-COV1901) in a participant-blinded, randomized, non-inferiority trial (NCT05054621). A total of 100 healthy adults aged 20–70 years having the first dose of ChAdOx1 were 1:1 randomly assigned to receive a booster dose either with ChAdOx1 (n = 50) or MVC-COV1901 (n = 50) at an interval of 4–6 or 8–10 weeks. At day 28 post-boosting, the neutralizing antibody geometric mean titer against wild-type SARS-CoV-2 in MVC-COV1901 recipients (236 IU/mL) was superior to that in ChAdOx1 recipients (115 IU/mL), with a GMT ratio of 2.1 (95% CI, 1.4 to 2.9). Superiority in the neutralizing antibody titer against Delta variant was also found for heterologous MVC-COV1901 immunization with a GMT ratio of 2.6 (95% CI, 1.8 to 3.8). Both spike-specific antibody-secreting B and T cell responses were substantially enhanced by the heterologous schedule. Heterologous boosting was particularly prominent at a short prime-boost interval. No serious adverse events occurred across all groups. The findings support the use of heterologous prime-boost with ChAdOx1 and protein-based subunit vaccines.

The Waxing, Waning, and Predictors of Humoral Responses to Vector-Based SARS-CoV-2 Vaccine in Hemodialysis Patients.

Hemodialysis (HD) patients are vulnerable to coronavirus disease 2019 (COVID-19) and have a high mortality rate. We evaluated the anti-SARS-CoV-2 spike protein antibody (ACOV2S) levels in 385 HD patients before and 4 and 8 weeks after the second dose of vector-based ChAdOx1 nCoV-19 vaccine. For study control, week 4 ACOV2S levels after the second vaccination dose were measured in 66 healthcare workers (HCWs). The seroconversion rate of HD patients was 98.96% 4 weeks after the second vaccination. Despite low antibody levels before the second dose (week 0), week 4 ACOV2S levels after the second vaccine dose in HD patients increased prominently and were compatible with those in HCWs (p = 0.814 for HCWs vs. HD patients). The ACOV2S levels in HD patients waned significantly 8 weeks after the second vaccination dose (p < 0.001 at week 8 vs. 4). Older age and immunosuppressant use were negative predictors, while higher C-reactive protein (CRP) levels were positive predictors of ACOV2S waxing after the second vaccine dose in HD patients. Higher CRP levels and platelet counts were independently associated with decreased ACOV2S waning. The ChAdOx1 nCoV-19 vaccine is effective and safe for primary vaccination in HD patients and a booster dose is necessary.

Withholding methotrexate after vaccination with ChAdOx1 nCov19 in patients with rheumatoid or psoriatic arthritis in India (MIVAC I and II): results of two, parallel, assessor-masked, randomised controlled trials.

BackgroundThere is a necessity for an optimal COVID-19 vaccination strategy for vulnerable population groups, including people with autoimmune inflammatory arthritis on immunosuppressants such as methotrexate, which inhibit vaccine-induced immunity against SARS-CoV-2. Thus, we aimed to assess the effects of withholding methotrexate for 2 weeks after each dose of ChAdOx1 nCov-19 (Oxford–AstraZeneca) vaccine (MIVAC I) or only after the second dose of vaccine (MIVAC II) compared with continuation of methotrexate, in terms of post-vaccination antibody titres and disease flare rates.MethodsMIVAC I and II were two parallel, independent, assessor-masked, randomised trials. The trials were done at a single centre (Dr Shenoy's Centre for Arthritis and Rheumatism Excellence; Kochi, India) in people with either rheumatoid arthritis or psoriatic arthritis with stable disease activity, who had been on a fixed dose of methotrexate for the preceding 6 weeks. Those with previous COVID-19 or who were positive for anti-SARS-CoV-2 nucleocapsid antibodies were excluded from the trials. People on high-dose corticosteroids and rituximab were also excluded, whereas other disease-modifying antirheumatic drugs were allowed. In MIVAC I, participants were randomly assigned (1:1) to stop methotrexate treatment for 2 weeks after each vaccine dose or to continue methotrexate treatment. In MIVAC II, participants who had continued methotrexate during the first dose of vaccine were randomly assigned (1:1) to withhold methotrexate for 2 weeks after the second dose of vaccine or to continue to take methotrexate. The treating physician was masked to the group assignments. The primary outcome for both MIVAC I and MIVAC II was the titre (absolute value) of anti-receptor binding domain (RBD) antibody measured 4 weeks after the second dose of vaccine. All analyses were done per protocol. The trials were registered with the Clinical Trials Registry- India, number CTRI/2021/07/034639 (MIVAC I) and CTRI/2021/07/035307 (MIVAC II).FindingsBetween July 6 and Dec 15, 2021, participants were recruited to the trials. In MIVAC I, 250 participants were randomly assigned and 158 completed the study as per the protocol (80 in the methotrexate hold group and 78 in the control group; 148 [94%] were women and 10 [6%] were men). The median post-vaccination antibody titres in the methotrexate hold group were significantly higher compared with the control group (2484·0 IU/mL, IQR 1050·0–4388·8 vs 1147·5 IU/mL, 433·5–2360·3; p=0·0014). In MIVAC II, 178 participants were randomly assigned and 157 completed the study per protocol (76 in the methotrexate hold group and 81 in the control group; 135 [86%] were women and 22 [14%] were men). The methotrexate hold group had higher post-vaccination antibody titres compared with the control group (2553·5 IU/ml, IQR 1792·5–4823·8 vs 990·5, 356·1–2252·5; p<0·0001). There were no reports of any serious adverse events during the trial period.InterpretationWithholding methotrexate after both ChAdOx1 nCov-19 vaccine doses and after only the second dose led to higher anti-RBD antibody titres compared with continuation of methotrexate. However, withholding methotrexate only after the second vaccine dose resulted in a similar humoral response to holding methotrexate after both vaccine doses, without an increased risk of arthritis flares. Hence, interruption of methotrexate during the second dose of ChAdOx1 nCov-19 vaccine appears to be a safe and effective strategy to improve the antibody response in patients with rheumatoid or psoriatic arthritis.FundingIndian Rheumatology Association.