Safety, immunogenicity, and reactogenicity of BNT162b2 and mRNA-1273 COVID-19 vaccines given as fourth-dose boosters following two doses of ChAdOx1 nCoV-19 or BNT162b2 and a third dose of BNT162b2 (COV-BOOST): a multicentre, blinded, phase 2, randomised trial

BACKGROUND

Some high-income countries have deployed fourth doses of COVID-19 vaccines, but the clinical need, effectiveness, timing, and dose of a fourth dose remain uncertain. We aimed to investigate the safety, reactogenicity, and immunogenicity of fourth-dose boosters against COVID-19.

METHODS

The COV-BOOST trial is a multicentre, blinded, phase 2, randomised controlled trial of seven COVID-19 vaccines given as third-dose boosters at 18 sites in the UK. This sub-study enrolled participants who had received BNT162b2 (Pfizer-BioNTech) as their third dose in COV-BOOST and randomly assigned them (1:1) to receive a fourth dose of either BNT162b2 (30 μg in 0·30 mL; full dose) or mRNA-1273 (Moderna; 50 μg in 0·25 mL; half dose) via intramuscular injection into the upper arm. The computer-generated randomisation list was created by the study statisticians with random block sizes of two or four. Participants and all study staff not delivering the vaccines were masked to treatment allocation. The coprimary outcomes were safety and reactogenicity, and immunogenicity (anti-spike protein IgG titres by ELISA and cellular immune response by ELISpot). We compared immunogenicity at 28 days after the third dose versus 14 days after the fourth dose and at day 0 versus day 14 relative to the fourth dose. Safety and reactogenicity were assessed in the per-protocol population, which comprised all participants who received a fourth-dose booster regardless of their SARS-CoV-2 serostatus. Immunogenicity was primarily analysed in a modified intention-to-treat population comprising seronegative participants who had received a fourth-dose booster and had available endpoint data. This trial is registered with ISRCTN, 73765130, and is ongoing.

FINDINGS

Between Jan 11 and Jan 25, 2022, 166 participants were screened, randomly assigned, and received either full-dose BNT162b2 (n=83) or half-dose mRNA-1273 (n=83) as a fourth dose. The median age of these participants was 70·1 years (IQR 51·6-77·5) and 86 (52%) of 166 participants were female and 80 (48%) were male. The median interval between the third and fourth doses was 208·5 days (IQR 203·3-214·8). Pain was the most common local solicited adverse event and fatigue was the most common systemic solicited adverse event after BNT162b2 or mRNA-1273 booster doses. None of three serious adverse events reported after a fourth dose with BNT162b2 were related to the study vaccine. In the BNT162b2 group, geometric mean anti-spike protein IgG concentration at day 28 after the third dose was 23 325 ELISA laboratory units (ELU)/mL (95% CI 20 030-27 162), which increased to 37 460 ELU/mL (31 996-43 857) at day 14 after the fourth dose, representing a significant fold change (geometric mean 1·59, 95% CI 1·41-1·78). There was a significant increase in geometric mean anti-spike protein IgG concentration from 28 days after the third dose (25 317 ELU/mL, 95% CI 20 996-30 528) to 14 days after a fourth dose of mRNA-1273 (54 936 ELU/mL, 46 826-64 452), with a geometric mean fold change of 2·19 (1·90-2·52). The fold changes in anti-spike protein IgG titres from before (day 0) to after (day 14) the fourth dose were 12·19 (95% CI 10·37-14·32) and 15·90 (12·92-19·58) in the BNT162b2 and mRNA-1273 groups, respectively. T-cell responses were also boosted after the fourth dose (eg, the fold changes for the wild-type variant from before to after the fourth dose were 7·32 [95% CI 3·24-16·54] in the BNT162b2 group and 6·22 [3·90-9·92] in the mRNA-1273 group).

INTERPRETATION

Fourth-dose COVID-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose.

FUNDING

UK Vaccine Task Force and National Institute for Health Research.

Immunological and pathological outcomes of SARS-CoV-2 challenge following formalin-inactivated vaccine in ferrets and rhesus macaques

There is an urgent requirement for safe and effective vaccines to prevent COVID-19. A concern for the development of new viral vaccines is the potential to induce vaccine-enhanced disease (VED). This was reported in several preclinical studies with both SARS-CoV-1 and MERS vaccines but has not been reported with SARS-CoV-2 vaccines. We have used ferrets and rhesus macaques challenged with SARS-CoV-2 to assess the potential for VED in animals vaccinated with formaldehyde-inactivated SARS-CoV-2 (FIV) formulated with Alhydrogel, compared to a negative control vaccine. We showed no evidence of enhanced disease in ferrets or rhesus macaques given FIV except for mild transient enhanced disease seen 7 days after infection in ferrets. This increased lung pathology was observed at day 7 but was resolved by day 15. We also demonstrate that formaldehyde treatment of SARS-CoV-2 reduces exposure of the spike receptor binding domain providing a mechanistic explanation for suboptimal immunity.

ChAdOx1 nCoV-19 protection against SARS-CoV-2 in rhesus macaque and ferret challenge models

Vaccines against SARS-CoV-2 are urgently required, but early development of vaccines against SARS-CoV-1 resulted in enhanced disease after vaccination. Careful assessment of this phenomena is warranted for vaccine development against SARS CoV-2. Here we report detailed immune profiling after ChAdOx1 nCoV-19 (AZD1222) and subsequent high dose challenge in two animal models of SARS-CoV-2 mediated disease. We demonstrate in rhesus macaques the lung pathology caused by SARS-CoV-2 mediated pneumonia is reduced by prior vaccination with ChAdOx1 nCoV-19 which induced neutralising antibody responses after a single intramuscular administration. In a second animal model, ferrets, ChAdOx1 nCoV-19 reduced both virus shedding and lung pathology. Antibody titre were boosted by a second dose. Data from these challenge models on the absence of enhanced disease and the detailed immune profiling, support the continued clinical evaluation of ChAdOx1 nCoV-19.

Quantification of SARS-CoV-2 neutralizing antibody by wild-type plaque reduction neutralization, microneutralization and pseudotyped virus neutralization assays

Virus neutralization assays measure neutralizing antibodies in serum and plasma, and the plaque reduction neutralization test (PRNT) is considered the gold standard for measuring levels of these antibodies for many viral diseases. We have developed procedures for the standard PRNT, microneutralization assay (MNA) and pseudotyped virus neutralization assay (PNA) for severe acute respiratory syndrome coronavirus 2. The MNA offers advantages over the PRNT by reducing assay time, allowing increased throughput and reducing operator workload while remaining dependent upon the use of wild-type virus. This ensures that all severe acute respiratory syndrome coronavirus 2 antigens are present, but Biosafety Level 3 facilities are required. In addition to the advantages of MNA, PNA can be performed with lower biocontainment (Biosafety Level 2 facilities) and allows for further increases in throughput. For each new vaccine, it is critical to ensure good correlation of the neutralizing activity measured using PNA against the PRNT or MNA. These assays have been used in the development and licensure of the ChAdOx1 nCoV-19 (AstraZeneca; Oxford University) and Ad26.COV2.S (Janssen) coronavirus disease 2019 vaccines and are critical for demonstrating bioequivalence of future vaccines.

Comparison of rhesus and cynomolgus macaques as an infection model for COVID-19

A novel coronavirus, SARS-CoV-2, has been identified as the causative agent of the current COVID-19 pandemic. Animal models, and in particular non-human primates, are essential to understand the pathogenesis of emerging diseases and to assess the safety and efficacy of novel vaccines and therapeutics. Here, we show that SARS-CoV-2 replicates in the upper and lower respiratory tract and causes pulmonary lesions in both rhesus and cynomolgus macaques. Immune responses against SARS-CoV-2 are also similar in both species and equivalent to those reported in milder infections and convalescent human patients. This finding is reiterated by our transcriptional analysis of respiratory samples revealing the global response to infection. We describe a new method for lung histopathology scoring that will provide a metric to enable clearer decision making for this key endpoint. In contrast to prior publications, in which rhesus are accepted to be the preferred study species, we provide convincing evidence that both macaque species authentically represent mild to moderate forms of COVID-19 observed in the majority of the human population and both species should be used to evaluate the safety and efficacy of interventions against SARS-CoV-2. Importantly, accessing cynomolgus macaques will greatly alleviate the pressures on current rhesus stocks.

Mutations in Kir2.1 Cause the Developmental and Episodic Electrical Phenotypes of Andersen's Syndrome

Andersen's syndrome is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We have mapped an Andersen's locus to chromosome 17q23 near the inward rectifying potassium channel gene KCNJ2. A missense mutation in KCNJ2 (encoding D71V) was identified in the linked family. Eight additional mutations were identified in unrelated patients. Expression of two of these mutations in Xenopus oocytes revealed loss of function and a dominant negative effect in Kir2.1 current as assayed by voltage-clamp. We conclude that mutations in Kir2.1 cause Andersen's syndrome. These findings suggest that Kir2.1 plays an important role in developmental signaling in addition to its previously recognized function in controlling cell excitability in skeletal muscle and heart.

Ancestral origins of the Machado-Joseph disease mutation: a worldwide haplotype study

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder originally described in families of Portuguese-Azorean ancestry. The cloning of the MJD1 gene allowed identification of the disease in many other populations, and MJD is now known to be the most common cause of dominant spinocerebellar ataxia. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised, both at historical and molecular levels. In the present study, we tested this hypothesis by linkage-disequilibrium analysis of tightly linked polymorphisms and by haplotype comparison, in 249 families from different countries. We typed five microsatellite markers surrounding the MJD1 locus (D14S1015, D14S995, D14S973, D14S1016, and D14S977), and three intragenic single-base-pair polymorphisms (A(669)TG/G(669)TG, C(987)GG/G(987)GG, and TAA(1118)/TAC(1118)). The results show two different haplotypes, specific to the island of origin, in families of Azorean extraction. In families from mainland Portugal, both Azorean haplotypes can be found. The majority of the non-Portuguese families also share the same intragenic haplotype seen in the families coming from the island of Flores, but at least three other haplotypes were seen. These findings suggest two introductions of the mutation into the Portuguese population. Worldwide, the sharing of one intragenic haplotype by the majority of the families studied implies a founder mutation in MJD.

Hepatic lipid peroxidation in hereditary hemochromatosis and alcoholic liver injury

Studies in experimental animals have indicated that enhanced lipid peroxidation may play a role in the hepatic injury produced by iron overload or by excessive alcohol consumption. The aim of this study was to compare the formation of lipid peroxidation-derived aldehydes in the liver of patients with hereditary hemochromatosis (HH) and alcohol abuse. Liver biopsy specimens from 10 nondrinking patients with HH were evaluated. These patients were classified as having HH based on hepatic iron index or human leukocyte antigen identity with a known proband. All patients were homozygous for the Cys282Tyr mutation. In addition, 8 patients with alcoholic liver disease were examined, 2 of whom also had hemochromatosis. For comparison, 17 patients with liver diseases unrelated to iron overload or alcohol abuse were studied. Liver biopsy specimens were immunostained for protein adducts with malondialdehyde and 4-hydroxynonenal. Both malondialdehyde- and 4-hydroxynonenal-protein adducts were found from liver specimens of patients with HH and alcohol abuse in more abundant amounts than from patients in a control group. In alcoholics the adducts were primarily in zone 3, whereas in hemochromatosis staining had an acinar zone 1 predominance, which followed the localization of iron. The most abundant amounts of protein adducts were noted in patients with alcohol abuse plus iron overload. The data support the concept that both chronic alcohol use and iron overload induce hepatic lipid peroxidation. Through formation of reactive aldehydic products, excessive alcohol consumption and iron overload may have additive hepatotoxic effects.

The safety of ropinirole, a selective nonergoline dopamine agonist, in patients with Parkinson's disease

Ropinirole is a novel, nonergoline, selective D2-type dopamine agonist developed to treat Parkinson's disease. Safety data from therapeutic studies involving 1364 patients receiving ropinirole are reported (mean daily dose 8.7 mg, early therapy; 8.2 mg adjunct therapy). In early therapy, the emergent adverse experiences more common with the ropinirole group compared with placebo were nausea, somnolence, leg edema, abdominal pain, vomiting, dyspepsia, and hallucinations. In adjunct therapy, they were dyskinesia, nausea, hallucinations, and confusion. Most adverse experiences were mild and associated with a similar withdrawal rate compared with the placebo group. Except for hallucinations, the incidence of emergent adverse experiences decreased with time, despite increasing doses. Long-term adverse experiences particularly associated with ergoline-type dopamine agonists have so far not been observed with ropinirole. Only 1.2% of patients receiving ropinirole developed dyskinesia compared with 11.2% receiving L-dopa in early therapy over a mean period of 17 months. There were no clinically significant changes in cardiovascular parameters or laboratory data. The incidence of adverse experiences in the bromocriptine group was low, possibly because of a slow titration scheme and low average dose. Overall, the safety profile of ropinirole appears similar to that of other dopamine agonists. Clinical studies are continuing to assess the long-term safety and efficacy of ropinirole.

Lipopolysaccharide (LPS) neutralizing peptides reveal a lipid A binding site of LPS binding protein

Endotoxic shock follows a cascade of events initiated by release of lipopolysaccharide during infection with Gram-negative organisms. Two overlapping 15-mer peptides were identified, corresponding to residues 91-108 of human lipopolysaccharide binding protein that specifically bound the lipid A moiety of lipopolysaccharide with high affinity. The peptides inhibited binding of lipopolysaccharide to lipopolysaccharide binding protein, inhibited the chromogenic Limulus amebocyte lysate reaction, and blocked release of tumor necrosis factor alpha following lipopolysaccharide challenge both in vitro and in vivo. These results suggest lipopolysaccharide binding protein residues 91-108 form at least part of the lipopolysaccharide binding site. Moreover, derivatives of lipopolysaccharide binding protein residues 91-108 might modulate lipopolysaccharide toxicity in the clinical setting.

Rapid infarct imaging with a technetium-99m-labeled antimyosin recombinant single-chain Fv: evaluation in a canine model of acute myocardial infarction

Studies of monoclonal antibody-based imaging agents show that blood clearance is inversely proportional to molecular size, i.e., Fab or Fab' > F(ab')2 > IgG. Indium-111-antimyosin Fab-DTPA is a highly specific and sensitive marker for myocardial necrosis. An improvement on current antibody diagnostic imaging may result from the use of smaller labeled fragments. We report the first in vivo targeting of acute myocardial infarction with a novel recombinant single-chain Fv (sFv) antimyosin protein. The sFv (MW = 27,594) is approximately one-half the size of the Fab and is comprised of the heavy and light chain variable regions from the myosin-specific murine monoclonal antibody R11D10 which were joined by a 15-amino-acid linker and expressed as a fusion protein (sFv) in E. coli. The binding affinity of the sFv for cardiac myosin was similar to the affinity observed for the Fab fragment. Technetium-99m labeling of the sFv was accomplished by the attachment of a cleavable, ester-linked bifunctional chelator (RP-1). Comparative studies in mice showed 99mTc-sFv-RP-1 cleared significantly faster (p < 0.001) than 99mTc-Fab'-RP-1 and 111In-Fab-DTPA antimyosin fragments. Furthermore, measurement of 99mTc-sFv-RP-1 blood clearance in a canine model of acute myocardial infarction gave a mean T1/2 of 0.54 +/- 0.13 hr versus 2.80 +/- 0.57 and 2.58 +/- 0.64 hr for Fab-DTPA and Fab'-RP-1 (p < 0.05), respectively. Despite its comparatively rapid clearance, 99mTc sFv-RP-1 had similar uptake in the infarct compared to the Fab'-RP-1. In addition, infarct visualization was more rapid with the sFv. Thus, these data demonstrate antimyosin sFv possesses characteristics necessary for rapid imaging of myocardial necrosis.

Low-attenuation periportal collar in transplanted liver is not reliable CT evidence of acute allograft rejection

Recent reports indicate that the presence or absence of a periportal low-attenuation rim ("periportal collar" sign) on CT scans is of variable reliability in predicting rejection after liver transplantation. To study this matter further, we reviewed 178 CT scans in 68 patients (74 allografts) after hepatic transplantation. One hundred twenty-one scans were obtained within 7 days of liver biopsy. The presence or absence of a central or peripheral periportal collar on these scans was correlated with the presence or absence of acute rejection found at biopsy. A central periportal collar was defined as an abnormally large amount of low-attenuation material surrounding the main portal vein, the right portal vein, or the left portal vein. A peripheral periportal collar was defined as a low-attenuation area surrounding a portal vein branch distal to the left or right portal veins. A weak, but statistically significant correlation between the presence of a peripheral periportal collar and acute allograft rejection was shown in patients in whom CT scans were obtained within 3 days of biopsy. However, the sensitivity, specificity, accuracy, and positive predictive value of the presence of a peripheral collar in this group were 60%, 67%, 64%, and 63%, respectively. The sensitivity, specificity, accuracy, and positive predictive value of the presence of a central collar in patients scanned within 3 days of biopsy were 74%, 35%, 54%, and 52%, respectively. Negative predictive values of peripheral and central collars were 65% and 59%, respectively. Our study shows that a periportal collar is seen more commonly in patients with recently transplanted allografts (mean interval after transplantation, 46 days for peripheral collars and 57 days for central collars) and in patients with ascites. The presence of a central or peripheral periportal collar on CT is not sufficiently sensitive, specific, or accurate to reliably diagnose or exclude acute allograft rejection.

High-performance liquid chromatographic assay and erythrocyte partitioning of fleroxacin, a new fluoroquinolone antibiotic

A rapid technique for sample preparation and HPLC was developed to study in vitro the erythrocyte binding and plasma protein binding of fleroxacin in the concentration range 0.2-15 micrograms ml-1. The red blood cell partition coefficient of fleroxacin was 1.45 +/- 0.18 at 25 degrees C and was independent of concentration, incubation time and temperature. The in vitro plasma protein binding of fleroxacin in humans, determined by two independent methods, was 47-51%. Partition studies using erythrocytes as a simple in vitro model may be useful to predict the degree of tissue uptake and the volume of distribution.

Mucosal arachidonate metabolism and intestinal ischemia-reperfusion injury

Mucosal arachidonic acid metabolism was examined after 3 h of ischemia and 1 h of reperfusion in isolated ileal segments in the dog. The cyclooxygenase products thromboxane B2, 6-ketoprostaglandin F1 alpha, and prostaglandin E2 increased by 365%, 97%, and 158%, respectively, after ischemia and reperfusion but were not altered after 3 h of ischemia alone. The potent chemotactic lipoxygenase product leukotriene B4 (LTB4) increased by 687% after ischemia and reperfusion and was not affected by ischemia without reperfusion. In addition, tissue production of the thiol ether leukotrienes (LTC4, LTD4, and LTE4) increased threefold after ischemia and reperfusion. Quantitation of regionally isomeric hydroxy acids produced from arachidonate revealed a 300% increase in 12-hydroxyeicosatetraenoate (12-HETE) after intestinal ischemia and reperfusion without a change in other isomers (15-HETE and 5-HETE). Stereochemical analysis of 12-HETE demonstrated exclusive synthesis of the S-enantiomer. A significant and time-dependent decrease in intestinal blood flow also occurred during reperfusion. Administration of the dual cyclooxygenase-lipoxygenase synthesis inhibitor BW755C (1 mg/kg ia) did not alter time-dependent decreases in blood flow and failed to inhibit eicosanoid synthesis. Histologic examinations of intestinal samples revealed significant mucosal damage associated with ischemia alone and ischemia after reperfusion. This study indicates that intestinal ischemia-reperfusion injury is associated with dramatic alterations in mucosal production of vasoactive eicosanoids and with changes in blood flow that occur during reperfusion but not during ischemia alone. These events may be involved in the pathology characteristic of this injury.

Thromboxane synthesis inhibition and renal allograft function

These data indicate that chronic administration of CGS-12970 to renal allograft recipients maintains renal allograft function. These effects are probably due to selective inhibition of local tissue TXA2 production. These data also suggest that elevations in renal allograft tissue prostacyclin production may be secondary to ischemia since improving renal blood flow and GFR with selective thromboxane synthesis inhibitors leads to normalization of renal prostacyclin synthesis. The possible utility of using CGS-12970 as an adjunct therapy in human renal allotransplantation should be strongly considered.

Use of ricin A-chain to selectively deplete Kupffer cells

We used the A-chain of the toxin ricin (RTA) as a toxin specific to Kupffer cells in mice. RTA is specifically taken up by the mannose receptor present exclusively in macrophages. Kupffer cells were quantitated by shifts in beta-glucuronidase clearance and microscopic counts of cells which phagocytosed India ink. When compared to saline controls, 20 mg/kg of RTA intraperitoneally (divided over 4 days) or intraportally (single doses) significantly prolonged the t 1/2 half-life of beta-glucuronidase by 270 +/- 37 and 210 +/- 8%, respectively. Kupffer cell numbers were significantly decreased by 27 +/- 8 and 33 +/- 16%. This effect persisted for at least 3 days after toxin administration. Despite effects on Kupffer cell number, minimal histological damage to liver, spleen, lung, and heart was noted. Higher doses of RTA or doses potentiated by ureteral ligation to prevent renal clearance resulted in prohibitive mortalities and histologic liver damage. Doses of Hura crepitans inhibitor, a toxin similar to RTA but not mannose-receptor specific, did not affect Kupffer cell numbers. We conclude that RTA given both intraperitoneally and intraportally at low doses is toxic specifically to Kupffer cells. Kupffer cell numbers can be indirectly measured by beta-glucuronidase clearance.

Essential fatty acid depletion of renal allografts and prevention of rejection

A central hypothesis in transplantation biology is that resident leukocytes expressing class II histocompatibility antigens may determine the immunogenicity of an organ. By means of a novel method to deplete the kidney of resident leukocytes, essential fatty acid deficiency (EFAD), this hypothesis was tested in an intact, vascular organ. Kidneys subjected to EFAD and thus depleted of resident Ia-positive macrophages survived and functioned when transplanted across a major histocompatibility antigen barrier in the absence of immunosuppression of the recipient. Control allografts were rejected promptly. Allografts from donors subjected to EFAD normalized their lipid composition and were repopulated with host macrophages by 5 days. Administration of Ia-positive cells at the time of transplantation established that the resident leukocyte depletion induced by EFAD was responsible for the protective effect. These observations may provide insights into the mechanisms underlying tissue immunogenicity and the population of normal tissues with resident leukocytes.

Eicosanoid synthesis inhibition and renal allograft function during acute rejection

The effects of the dual cyclooxygenase-lipoxygenase inhibitor 3-amino-1-(m[trifluoromethyl]phenyl)-2-pyrazoline (BW755C) (10 mg/kg, p.o., b.i.d.) on renal blood flow, glomerular filtration rate (GFR), and eicosanoid production were examined in anesthetized dogs that had undergone unilateral renal allotransplantation. Rejecting renal allograft blood flow significantly declined over a 5-day period compared to the nonrejecting native kidney. In animals treated with BW755C, renal allograft blood flow was maintained over the postoperative 5-day period at levels comparable to blood flow to the native kidneys. While GFR and urine flow progressively declined in the rejecting kidney, treatment with BW755C prevented the fall in GFR and even augmented urine flow. Allograft renal cortical production or thromboxane B2 (TXB2) and leukotriene B4 (LTB4) in animals treated with BW755C was not significantly different than production by the native contralateral kidneys. Furthermore, BW755C reduced cellular infiltration and tissue damage in allografts compared to nontreated renal allografts. The selective cyclooxygenase inhibitor, indomethacin (5 mg/kg, p.o., b.i.d.) exerted no effect on renal allograft GFR or urine output but reduced allograft blood flow after 4 days compared to nontreated allografts. In conclusion, inhibition of arachidonate cyclooxygenase and lipoxygenase metabolism improves renal allograft function and reduces tissue damage while selective inhibition of the cyclooxygenase pathway does not improve renal allograft function. These data indicate that products of arachidonate-lipoxygenase metabolism potentiate the loss of renal function and tissue destruction associated with renal allograft rejection.