Modelling the impact of hybrid immunity on future COVID-19 epidemic waves

BACKGROUND

Since the emergence of SARS-CoV-2 (COVID-19), there have been multiple waves of infection and multiple rounds of vaccination rollouts. Both prior infection and vaccination can prevent future infection and reduce severity of outcomes, combining to form hybrid immunity against COVID-19 at the individual and population level. Here, we explore how different combinations of hybrid immunity affect the size and severity of near-future Omicron waves.

METHODS

To investigate the role of hybrid immunity, we use an agent-based model of COVID-19 transmission with waning immunity to simulate outbreaks in populations with varied past attack rates and past vaccine coverages, basing the demographics and past histories on the World Health Organization Western Pacific Region.

RESULTS

We find that if the past infection immunity is high but vaccination levels are low, then the secondary outbreak with the same variant can occur within a few months after the first outbreak; meanwhile, high vaccination levels can suppress near-term outbreaks and delay the second wave. Additionally, hybrid immunity has limited impact on future COVID-19 waves with immune-escape variants.

CONCLUSIONS

Enhanced understanding of the interplay between infection and vaccine exposure can aid anticipation of future epidemic activity due to current and emergent variants, including the likely impact of responsive vaccine interventions.

Disaster differentially affects underserved communities

Patients with barriers to care, including poverty and language barriers, often live in lower-cost, disaster-prone areas. Partnering with community clinics enables allergists to reach underserved patients.

Thermality versus Objectivity: Can They Peacefully Coexist?

Under the influence of external environments, quantum systems can undergo various different processes, including decoherence and equilibration. We observe that macroscopic objects are both objective and thermal, thus leading to the expectation that both objectivity and thermalisation can peacefully coexist on the quantum regime too. Crucially, however, objectivity relies on distributed classical information that could conflict with thermalisation. Here, we examine the overlap between thermal and objective states. We find that in general, one cannot exist when the other is present. However, there are certain regimes where thermality and objectivity are more likely to coexist: in the high temperature limit, at the non-degenerate low temperature limit, and when the environment is large. This is consistent with our experiences that everyday-sized objects can be both thermal and objective.

Health status relating to cigarette smoking among Raglai ethnic minority women in Khanh Hoa Province, Viet Nam

OBJECTIVE: To examine possible associations between body mass index (BMI), blood pressure and smoking status among Raglai ethnic minority women. Some sociocultural factors were also considered in the related association.METHOD: A cross-sectional design was used in this study conducted among Raglai ethnic minority women aged 15-49 years, who are currently living in two mountainous districts, Khanh Son and Khanh Vinh, in Khanh Hoa Province of Viet Nam. Study variables included current smoking status, physical indices, blood pressure and some related sociocultural factors.RESULTS: Based on the data from 613 respondents who completed the study questionnaire, the results showed current smoking prevalence among Raglai ethnic minority women aged 15-49 to be 16.6%. Compared with non-smokers, current smoker women had significantly lower BMI and higher blood pressure. Smoking prevalence among illiterate and non-religious women was significantly higher than educated and religious ones.CONCLUSION: The current smoking prevalence among Raglai ethnic minority women aged 15-49 years was 16.6%. Significantly lower BMI and higher blood pressure were observed among current smokers than among non-smokers. The prevalence among educated and religious women was significantly lower than among illiterate and non-religious women.

Strong Quantum Darwinism and Strong Independence are Equivalent to Spectrum Broadcast Structure

How the objective everyday world emerges from the underlying quantum behavior of its microscopic constituents is an open question at the heart of the foundations of quantum mechanics. Quantum Darwinism and spectrum broadcast structure are two different frameworks providing key insight into this question. Recent works, however, indicate these two frameworks can lead to conflicting predictions on the objectivity of the state of a system interacting with an environment. Here, we provide a resolution to this issue by defining strong quantum Darwinism and proving that it is equivalent to spectrum broadcast structure when combined with strong independence of the subenvironments. We further show that strong quantum Darwinism is sufficient and necessary to signal state objectivity without the requirement of strong independence. Our Letter unveils the deep connection between strong quantum Darwinism and spectrum broadcast structure, thereby making fundamental progress toward understanding and solving the emergence of classicality from the quantum world. Together they provide us a sharper understanding of the transition in terms of state structure, geometry, and quantum and classical information.

IRIS iQ200 workstation as a screen for performing urine culture

We cultured 1000 urines and tested them with the iQ200 Workstation (Iris Diagnostics, Chatsworth, CA, and Arkray, Edina, MN, USA) for leukocyte esterase and nitrite (LE/N), white blood cells (WBC), all small particles (ASP), bacteria, and yeast. Positive culture grew ≥ 10(4) CFU/mL of 1 or 2 uropathogens. Method A assessed LE/N, WBCs ≥ 6/μL, and bacteria/yeast. Method B assessed WBCs ≥ 6/μL, bacteria/yeast, and ASP ≥ 10,000. Each was compared to culture results, clinician's diagnosis (CD), or expert review (ER). Sensitivities by culture were 88.7% (Method A) and 88.3% (Method B), with negative predictive values (NPVs) of 94.4% and 94.2%, respectively. Sensitivity and NPV increased for comparison to the CD (99.6%) and NPVs of 99.0% and 99.3% compared to ER. ASP did not enhance specificity, sensitivity, or NPV. The iQ200 Workstation performed well by any standard, thus providing a reliable system by which to improve the use of laboratory resources.

RAC3 is a pro-migratory co-activator of ERα

ERα is a ligand-dependent nuclear receptor that is important in breast cancer genesis, behavior and response to hormone-based therapies. A T7 phage display screen against full-length human ERα, coupled with genome-wide exon arrays, was used to identify RAC3 as a putative ERα co-regulator. RAC3 is a rho family small GTPase that is associated with cytoskeletal rearrangement. We demonstrate a novel role for nuclear RAC3 as an ERα transcriptional activator, with prognostic implications for metastatic disease. Through in vitro and cell-based studies, RAC3 was shown to exist in a GTP-bound state and act as a ligand specific ERα co-activator of E2-induced transcription. Over expression of RAC3 induced pro-growth and pro-migratory genes that resulted in increased migration of ERα-positive breast cancer cells. Chemical inhibition and genetic knockdown of RAC3 antagonized E2-induced cell proliferation, cell migration, and ERα mediated gene expression, indicating that RAC3 is necessary for full ERα transcriptional activity. In agreement with the molecular and cellular data, RAC3 over expression in ERα-positive breast cancers correlated with a significant decrease in recurrence free survival and a significant increase in the odds ratio of metastasis. In conclusion, RAC3 is novel ERα co-activator that promotes cell migration and has prognostic value for ERα-positive breast cancer metastasis. RAC3 may also be a useful therapeutic target for ERα-positive breast cancers.

Infantile mitochondrial DNA depletion syndrome associated with methylmalonic aciduria and 3-methylcrotonyl-CoA and propionyl-CoA carboxylase deficiencies in two unrelated patients: a new phenotype of mtDNA depletion syndrome

Mitochondrial DNA (mtDNA) depletion refers to a quantitative defect in mtDNA and is heterogeneous with regard to causal genotypes and the associated clinical phenotypes. We report two unrelated infants with mtDNA depletion. A diagnosis of methylmalonic aciduria was initially raised in both on the basis of high urine methylmalonic acid and related organic acids and elevated propionylcarnitine and methylmalonylcarnitine. Carboxylase assay with skin fibroblasts revealed low propionyl-CoA and 3-methylcrotonyl-CoA carboxylase and normal pyruvate carboxylase activities. Quantitative Southern blot analysis of mitochondrial and nuclear DNA with muscle tissues revealed the patients' mtDNA to be depleted to 24% and 39% of normal controls. Our two patients showed multiple mitochondrial dysfunction including respiratory chain defects and deficiencies in the two nuclear DNA encoded carboxylases resulting in abnormal urine organic acids. To our knowledge, there is no obvious connection between the defective pathways other than their mitochondrial locations. These two cases may represent a new entity of mitochondrial disease that might be due to a defective common mechanism, such as assembly, maintenance and transport, affecting various mitochondrial enzymes and functions. Mitochondrial depletion should be considered in infants with atypical organic aciduria that may resemblemethylmalonicaciduria, propionicacidaemia, or 3-methylcrotonyl-CoA carboxylase deficiency.

Empirical therapy for uncomplicated urinary tract infections in an era of increasing antimicrobial resistance: a decision and cost analysis

Infectious Diseases Society of America guidelines state that uncomplicated urinary tract infections (UTIs) should be treated empirically with trimethoprim-sulfamethoxazole (TMP-SMZ), unless the community resistance among uropathogens exceeds 10%-20%, in which case a fluoroquinolone (FQ) should be used. However, the data to support this threshold are limited. We performed a cost-minimization and sensitivity analysis to determine what level of TMP-SMZ resistance in a community should trigger FQ use. The mean cost of empirical treatment with TMP-SMZ was US$92 when the proportion of resistant Escherichia coli was 0%, $106 when it was 20%, and $120 when it was 40%. The mean cost of empirical FQ treatment was $107 at current levels of FQ resistance. When >22% of E. coli in a community are TMP-SMZ-resistant, empirical FQ therapy becomes less costly than TMP-SMZ therapy. Treatment guidelines for empirical treatment of UTIs may need modification, and the threshold trigger for empirical FQ use should be raised to >20% TMP-SMZ resistance.

HLA-A*01-restricted cytotoxic T-lymphocyte epitope from the Plasmodium falciparum circumsporozoite protein

Here, we report the identification of a novel CD8+ cytotoxic T-lymphocyte epitope on the Plasmodium falciparum circumsporozoite protein (3D7; amino acids 310 to 319 [EPSDKHIKEY]) that is restricted by HLA-A*01 and is recognized by human volunteers immunized with irradiated P. falciparum sporozoites. HLA-A*01 is the second most common HLA allele among Caucasians.

Nucleotide oxidation mediated by naphthalimide excited states with covalently attached viologen cosensitizers

The ground- and excited-state interactions of polymethylene-linked 1,8-naphthalimide-viologen dyads with calf-thymus DNA have been investigated. By virtue of the covalently attached viologen, the compounds represent the first example of linked chromophore/cosensitizer systems in the photooxidation of duplex DNA. The compounds associate strongly with DNA. Analysis of ground-state spectral changes yield binding constants of 0.7-2.5 x 10(6) M-1. Upon 355 nm pulsed irradiation of the compounds in the presence of calf-thymus DNA, reduced viologen is observed within the laser pulse. Photoproducts are not observed on this time scale in the absence of DNA. Since ground-state bleaching of the naphthalimide was not observed, the results suggest that DNA nucleobases are the species being oxidized. The quantum efficiency of radical production increases with the extent of binding to DNA. Under conditions where the compounds are bound predominantly to DNA, the quantum efficiencies were found to range from 0.02 to 0.03. Although small, the values represent a substantial increase in charge-separation yield compared to 1,8-naphthalimide compounds that lack the covalently attached viologen. The mechanism of radical production and effect of number of intervening methylenes are discussed.

Safety, tolerability and humoral immune responses after intramuscular administration of a malaria DNA vaccine to healthy adult volunteers

DNA-based vaccines are considered to be potentially revolutionary due to their ease of production, low cost, long shelf life, lack of requirement for a cold chain and ability to induce good T-cell responses. Twenty healthy adult volunteers were enrolled in a Phase I safety and tolerability clinical study of a DNA vaccine encoding a malaria antigen. Volunteers received 3 intramuscular injections of one of four different dosages (20, 100, 500 and 2500 microg) of the Plasmodium falciparum circumsporozoite protein (PfCSP) plasmid DNA at monthly intervals and were followed for up to twelve months. Local reactogenicity and systemic symptoms were few and mild. There were no severe or serious adverse events, clinically significant biochemical or hematologic changes, or detectable anti-dsDNA antibodies. Despite induction of excellent CTL responses, intramuscular DNA vaccination via needle injection failed to induce detectable antigen-specific antibodies in any of the volunteers.

Induction of antigen-specific cytotoxic T lymphocytes in humans by a malaria DNA vaccine

CD8+ cytotoxic T lymphocytes (CTLs) are critical for protection against intracellular pathogens but often have been difficult to induce by subunit vaccines in animals. DNA vaccines elicit protective CD8+ T cell responses. Malaria-naïve volunteers who were vaccinated with plasmid DNA encoding a malaria protein developed antigen-specific, genetically restricted, CD8+ T cell-dependent CTLs. Responses were directed against all 10 peptides tested and were restricted by six human lymphocyte antigen (HLA) class I alleles. This first demonstration in healthy naïve humans of the induction of CD8+ CTLs by DNA vaccines, including CTLs that were restricted by multiple HLA alleles in the same individual, provides a foundation for further human testing of this potentially revolutionary vaccine technology.

Double-helix coil for occlusion of large patent ductus arteriosus: evaluation in a chronic lamb model

OBJECTIVES

We sought to evaluate the efficacy and tissue reaction of a new miniature interventional device for occlusion of large patent ductus arteriosus (PDA) in a neonatal lamb model.

BACKGROUND

A variety of devices are used to close PDAs by interventional measures. Spring coils found to have a high cumulative occlusion rate have thus far been limited to smaller PDAs because of the physical limitation of grip forces.

METHODS

Memory-shaped double-cone stainless steel coils with enhanced stiffness of the outer rings by a double-helix configuration were mounted on a titanium/nickel core wire. A snap-in mechanism attaches the coil to the delivery wire, allowing intravascular coil retrieval and repositioning. The system was placed through a 4F or 5F Teflon catheter. A chronic lamb model (n = 8) of PDA (>5 mm) was used in which ductus patency was secured by a protocol of repetitive angioplasty procedures. The animals were killed after 1 to 181 days, and the ductal region was examined by inspection as well as by light and electron microscopy.

RESULTS

Placement of the coils within the PDA was possible in all lambs. Before final detachment, the coils were retrieved or repositioned, or both, up to 12 times. In all but one animal the ductus was closed within 6 days after the procedure. The coils caused no infections or aortic and pulmonary artery obstruction. Histologic and electron microscopic studies revealed endothelial coverage of the implants but no foreign body reaction or local or systemic inflammation or erosion of the implant.

CONCLUSIONS

The device effectively closed large PDAs in our model and may overcome the previous limitations of coils. Clinical trials are indicated.

Immunogenicity of Plasmodium falciparum circumsporozoite protein multiple antigen peptide vaccine formulated with different adjuvants

Only low antibody levels were obtained from vaccinating human volunteers with single-chain peptide from the Plasmodium falciparum circumsporozoite protein (PfCSP). This resulted in modest protection against sporozoite challenge. In addition, HLA restriction limits the probability of synthesis of a vaccine effective for a diverse population. We report immunization studies with a multiple antigen peptide (MAP) system consisting of multiple copies of a B-cell epitope from the central repeat region of the PfCSP in combination with a universal T-cell epitope, the P2P30 portion of tetanus toxin. This MAP4(NANP)6P2P30 vaccine was highly immunogenic in four different strains of mice when used with various safe and nontoxic adjuvants. When this MAP vaccine was encapsulated in liposomes with lipid A and adsorbed to aluminium hydroxide and given three times at 4-week intervals, the resultant antibody prevented 100% of sporozoites from invading and developing into liver stage infection. This high degree of immunogenicity of MAP4(NANP)6P2P30 vaccine formulated in liposomes, lipid A and aluminum hydroxide provides the foundation for consideration of human trials with this formulation.

Toward clinical trials of DNA vaccines against malaria

In mid 1997 the first malaria DNA vaccine will enter clinical trials. This single gene DNA vaccine encoding the Plasmodium falciparum circumsporozoite protein (PfCSP) will be studied for safety and immunogenicity. If these criteria are met, a multi-gene DNA vaccine designed to induce protective CD8+ T cell responses against P. falciparum infected hepatocytes will be subsequently assessed for safety, immunogenicity and capacity to protect immunized volunteers against experimental challenge with P. falciparum sporozoites. Our perspectives on malaria vaccine development in general, and on a multi-gene DNA vaccine in particular, have been recently reviewed. Herein, we review the rationale and experimental foundation for the anticipated P. falciparum DNA vaccine trials.

Short courses of ofloxacin for the treatment of enteric fever

Typhoid fever continues to be a major public health problem in tropical countries, exacerbated in recent years by the spread of multi-drug resistant strains of Salmonella typhi. Short treatment courses of fluoroquinolones are effective, and have the advantage of reduced cost and increased compliance, but the optimal length of treatment is unknown. In an open, randomized comparison, 107 adults with uncomplicated enteric fever (95 of whom had positive blood cultures for S. typhi and 5 for S. paratyphi) were treated with oral ofloxacin, 15 mg/kg/d for 2 d or 10 mg/kg/d for 3 d. Mean fever clearance times were the same in the 2 treatment groups (97 h). There were 7 treatment failures, one in the 2 d group and 6 in the 3 d group (P = 0.07). Three of the 5 patients infected with nalidixic acid resistant strains of S. typhi had treatment failures, compared with 4 of 90 with nalidixic acid sensitive isolates (P < 0.0001; relative risk 13.5, 95% confidence interval 4.1-43%). Treatment with ofloxacin for 2 or 3 d is equally effective in adults with uncomplicated enteric fever caused by nalidixic acid sensitive strains of S. typhi. The epidemiology and management of nalidixic acid resistent typhoid needs further investigation.

Clinical manifestations of Plasmodium falciparum malaria experimentally induced by mosquito challenge

To determine the characteristics of clinical illness accompanying Plasmodium falciparum infection induced by controlled exposure to infected mosquitoes, records of 118 volunteers participating in studies conducted between 1985 and 1992 were reviewed. One hundred fourteen volunteers (97%) reported at least one symptom attributable to malaria, with fatigue, myalgias or arthralgias, headache, and chills most commonly reported. The median duration of symptoms was 3 days. Fever was recorded in 61% of volunteers; 4 volunteers had temperatures >40 degrees C. Neutropenia and thrombocytopenia were present in 9% and 12% of volunteers, respectively. Despite counts as low as 658/microL (neutrophils) or 73,000/microL (platelets), no secondary infectious or hemorrhagic complications occurred. In all cases, volunteers recovered completely and laboratory values returned to baseline after specific antimalarial therapy. Recrudescence did not occur in any volunteer. In this model, mosquito inoculation of P. falciparum is a reliable, safe, and well-tolerated method of experimental challenge.

Occlusion of the neonatal patent ductus arteriosus with a simple retrievable device: a feasibility study

PURPOSE

To examine the feasibility of transvenous placement of a new memory-shaped, small, retrievable coil that has a smaller-caliber delivery system than currently available devices, for closure of the patent ductus arteriosus (PDA).

METHODS

Through 4 or 5 Fr vascular sheaths and 4 or 5 Fr end-hold catheters, the coils were delivered and placed in piglets (n = 10) with PDA. The coils were made from 0.018" (0.46 mm) or 0.028" (0.71 mm) stainless steel guidewire. Mounted for delivery, the new device has the appearance of a conventional guidewire. This neonatal PDA model was created without major surgery or drugs by stenting the ductus arteriosus.

RESULTS

The memory-shaped coils were easily delivered. Coils not optimally placed were retrieved and repositioned. Occlusion of the ductus arteriosus as early as a half-hour after delivery was shown angiographically and confirmed by histopathology.

CONCLUSION

This new, small-caliber, simple device was found to be effective for closure of the PDA in this animal model. Longer-term observations are needed.

Short course of ofloxacin for treatment of multidrug-resistant typhoid

In recent years, multiresistant strains of Salmonella typhi have emerged in many tropical countries. These strains remain highly sensitive to the fluoroquinolone antibiotics, although use of these drugs by children is considered contraindicated because of their reported toxicity in the cartilage of experimental animals. In a paired, open, randomized study during an epidemic of multidrug-resistant typhoid in southern Vietnam, two short-course ofloxacin regimens (15 mg/kg daily for 3 days and 10 mg/kg daily for 5 days) were compared for the treatment of uncomplicated typhoid fever. Of 438 patients enrolled (of whom 286 were < or = 14 years old), 228 had blood cultures positive for Salmonella species (S. typhi, 207; S. paratyphi A, 19; and S. choleraesuis, 2). There was one treatment failure in a patient who took only one dose of ofloxacin. Otherwise, both regimens were completely effective; there were no proven carriers, and there was no evidence of toxicity, particularly in children. A 3-day course of ofloxacin proved to be safe and highly effective in the treatment of uncomplicated, multidrug-resistant typhoid fever.

Long-term evaluation of immune status in leprosy patients undergoing multiple drug therapy

A long-term survey of leprosy patients of all clinical types, starting at the time of diagnosis, was carried out to monitor clinical, bacteriological and immunological parameters at regular intervals during multiple drug therapy (MDT). The patients were assigned to two groups for treatment following WHO guidelines: paucibacillary (PB) and multibacillary (MB). Immunoglobulin levels, specific antibodies, skin-test responses to different soluble mycobacterial antigens (new tuberculins), and in vitro proliferative responses to mitogens and to antigens were measured during treatment, as were clinical changes, the bacterial index, and clinical improvement. No exact relations between disease activity and IgM antibody levels, both IgM immunoglobulin and specific IgM antibody to a species-specific antigen (ND-O-BSA), could be seen for MB patients. Changes in in vitro cell-mediated immunity and skin-test response seemed to be more directly related to the bacterial load and could reflect the improvement of bacteriological and clinical parameters during MDT.