What is the economic benefit of annual COVID-19 vaccination from the adult individual perspective?

BACKGROUND

With COVID-19 vaccination no longer mandated by many businesses/organizations, it is now up to individuals to decide whether to get any new boosters/updated vaccines going forward.

METHODS

We developed a Markov model representing the potential clinical/economic outcomes from an individual perspective in the United States of getting versus not getting an annual COVID-19 vaccine.

RESULTS

For an 18-49-year-old, getting vaccinated at its current price ($60) can save the individual on average $30-$603 if the individual is uninsured and $4-$437 if the individual has private insurance, as long as the starting vaccine efficacy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is ≥50% and the weekly risk of getting infected is ≥0.2%, corresponding to an individual interacting with 9 other people in a day under Winter 2023-2024 Omicron SARS-CoV-2 variant conditions with an average infection prevalence of 10%. For a 50-64-year-old, these cost-savings increase to $111-$1,278 and $119-$1,706, for someone without and with insurance, respectively. The risk threshold increases to ≥0.4% (interacting with 19 people/day), when the individual has 13.4% pre-existing protection against infection (e.g., vaccinated 9 months earlier).

CONCLUSION

There is both clinical and economic incentive for the individual to continue to get vaccinated against COVID-19 each year.

How the Timing of Annual COVID-19 Vaccination of Nursing Home Residents and Staff Affects Its Value

OBJECTIVES

To evaluate the epidemiologic, clinical, and economic value of an annual nursing home (NH) COVID-19 vaccine campaign and the impact of when vaccination starts.

DESIGN

Agent-based model representing a typical NH.

SETTING AND PARTICIPANTS

NH residents and staff.

METHODS

We used the model representing an NH with 100 residents, its staff, their interactions, COVID-19 spread, and its health and economic outcomes to evaluate the epidemiologic, clinical, and economic value of varying schedules of annual COVID-19 vaccine campaigns.

RESULTS

Across a range of scenarios with a 60% vaccine efficacy that wanes starting 4 months after protection onset, vaccination was cost saving or cost-effective when initiated in the late summer or early fall. Annual vaccination averted 102 to 105 COVID-19 cases when 30-day vaccination campaigns began between July and October (varying with vaccination start), decreasing to 97 and 85 cases when starting in November and December, respectively. Starting vaccination between July and December saved $3340 to $4363 and $64,375 to $77,548 from the Centers for Medicare & Medicaid Services and societal perspectives, respectively (varying with vaccination start). Vaccination's value did not change when varying the COVID-19 peak between December and February. The ideal vaccine campaign timing was not affected by reducing COVID-19 levels in the community, or varying transmission probability, preexisting immunity, or COVID-19 severity. However, if vaccine efficacy wanes more quickly (over 1 month), earlier vaccination in July resulted in more cases compared with vaccinating later in October.

CONCLUSIONS AND IMPLICATIONS

Annual vaccination of NH staff and residents averted the most cases when initiated in the late summer through early fall, at least 2 months before the COVID-19 winter peak but remained cost saving or cost-effective when it starts in the same month as the peak. This supports tethering COVID vaccination to seasonal influenza campaigns (typically in September-October) for providing protection against SARS-CoV-2 winter surges in NHs.

Recombinant expression systems for the production of collagen

The ability of triple-helical collagen molecules to assemble into supramolecular structures forms the basis of commercial uses of collagen in the food industry and in medical applications such as cosmetic surgery and tissue repair. We have used cDNA techniques to engineer novel collagens with potentially enhanced biological properties; however, expression of fully functional novel molecules is difficult due to the complex nature of procollagen biosynthesis. This article outlines the application of various expression systems to procollagen production and details the use of the mammary gland as a suitable bioreactor for the synthesis of significant amounts of novel procollagens from cDNA constructs.

Expression of an engineered form of recombinant procollagen in mouse milk

We have examined the suitability of the mouse mammary gland for expression of novel recombinant procollagens that can be used for biomedical applications. We generated transgenic mouse lines containing cDNA constructs encoding recombinant procollagen, along with the alpha and beta subunits of prolyl 4-hydroxylase, an enzyme that modifies the collagen into a form that is stable at body temperature. The lines expressed relatively high levels (50-200 micrograms/ml) of recombinant procollagen in milk. As engineered, the recombinant procollagen was shortened and consisted of a pro alpha 2(I) chain capable of forming a triple-helical homotrimer not normally found in nature. Analysis of the product demonstrated that (1) the pro alpha chains formed disulphide-linked trimers, (2) the trimers contained a thermostable triple-helical domain, (3) the N-propeptides were aligned correctly, and (4) the expressed procollagen was not proteolytically processed to collagen in milk.

Intracellular dissociation and reassembly of prolyl 4-hydroxylase:the alpha-subunits associated with the immunoglobulin-heavy-chain binding protein (BiP) allowing reassembly with the beta-subunit

Prolyl 4-hydroxylase (P4-H) consists of two distinct polypeptides; the catalytically more important alpha-subunit and the beta-subunit, which is identical to the multifunctional enzyme protein disulphide isomerase. The enzyme appears to be assembled in vivo into an alpha 2 beta 2 tetramer from newly synthesized alpha-subunits associating with an endogenous pool of beta-subunits. Using a cell-free system, we have shown previously that enzyme assembly is redox-dependent and that assembled alpha-subunits are intramolecularly disulphide-bonded [John and Bulleid (1994) Biochemistry 33, 14018-14025]. Here we have studied this assembly process within intact cells by expressing both subunits in COS-1 cells. Newly synthesized alpha-subunits were shown to assemble with the beta-subunit, to form insoluble aggregates, or to remain soluble but not associate with the beta-subunit. Treatment of cells with dithiothreitol (DTT) led to dissociation of P4-H into subunits and on removal of DTT the enzyme reassembled. This reassembly was ATP-dependent, suggesting an interaction with an ATP-dependent chaperone. This was confirmed when immunoglobulin-heavy-chain binding protein (BiP) and alpha-subunits were co-immunoprecipitated with antibodies against the alpha-subunit and BiP, respectively. These results indicate that unassembled alpha-subunits are maintained in an assembly-competent form by interacting with the molecular chaperone BiP.

Prolyl 4-hydroxylase: defective assembly of alpha-subunit mutants indicates that assembled alpha-subunits are intramolecularly disulfide bonded

The vital hydroxylation of peptidyl proline residues in collagens and protein with collagen-like amino acid sequences is catalyzed by the tetrameric enzyme prolyl 4-hydroxylase (P4-H). We have previously detailed [John et al. (1993) EMBO J. 12, 1587-1595] the redox-dependent assembly of the catalytically important alpha-subunit (64 kDa) in a cell-free system containing endogenous beta-subunits (PDI, 60 kDa). To identify the origin of this redox-dependent assembly, we have now shown directly by an electrophoretic mobility shift assay that the assembled wild-type protein possesses at least one intramolecular disulfide bond. We also analyzed five alpha-subunit mutants that have single Cys to Ser mutations in one of the five Cys residues present in the wild-type protein and found that (i) subunits mutated at Cys150 or Cys511 formed intramolecular disulfide bonds, whereas subunits mutated at Cys276, Cys293, or Cys486 did not, (ii) mutation of Cys276, Cys293, or Cys486 led to a large reduction in alpha-beta complex formation, (iii) subunits mutated at Cys276, Cys293, Cys486, or Cys511 were recognized by an antiserum raised against an alpha-subunit C-terminal peptide which failed to recognize the assembled wild-type subunit or the assembled subunit mutated at Cys150, and (iv) the assembled complexes fractionated in a similar position to the purified protein on sucrose gradients whereas the assembly-defective mutants formed higher molecular weight aggregates or complexes with other proteins. On the basis of these results, we propose that P4-H alpha-subunits possess an intramolecular disulfide bond between Cys276 and Cys293 that is essential for alpha-beta complex formation.

Cell-free synthesis and assembly of prolyl 4-hydroxylase: the role of the beta-subunit (PDI) in preventing misfolding and aggregation of the alpha-subunit

Prolyl 4-hydroxylase (P4-H) catalyses a vital post-translational modification in the biosynthesis of collagen. The enzyme consists of two distinct polypeptides forming an alpha 2 beta 2 tetramer (alpha = 64 kDa, beta = 60 kDa), the beta-subunit being identical to the multifunctional enzyme protein disulfide isomerase (PDI). By studying the cell-free synthesis of the rat alpha-subunit of P4-H we have shown that the alpha-subunit can be translocated, glycosylated and the signal peptide cleaved by dog pancreatic microsomal membranes to yield both singly and doubly glycosylated forms. When translations were carried out under conditions which prevent disulfide bond formation, the product synthesized formed aggregates which were associated with the immunoglobulin heavy chain binding protein (BiP). Translations carried out under conditions that promote disulfide bond formation yielded a product that was not associated with BiP but formed a complex with the endogenous beta-subunit (PDI). Complex formation was detected by co-precipitation of the newly synthesized alpha-subunit with antibodies raised against PDI, by sucrose gradient centrifugation and by chemical cross-linking. When microsomal vesicles were depleted of PDI, BiP and other soluble endoplasmic reticulum proteins, no complex formation was observed and the alpha-subunit aggregated even under conditions that promote disulfide bond formation. We have therefore demonstrated that the enzyme P4-H can be assembled at synthesis in a cell-free system and that the solubility of the alpha-subunit is dependent upon its association with PDI.

Sequence-dependent reactivity of linear DNA to chemical cleavage by Cu(II):thiol combinations including cysteine or glutathione

The chemical cleavage of linear DNA by Cu(II):thiol combinations was investigated using end-labelled double-stranded restriction fragments. Single-strand cleavage of the target DNA occurred with apparent sequence preference, but there appeared to be no apparent consensus sequence for such preferentially cleaved sites based on studies of three different restriction fragments. For any given restriction fragment, the observed Cu(II):thiol DNA-cleavage sequence preference was found to be independent of the nature of the thiol used. Cleavage of 3'-end-labelled DNA generated fragments bearing 5'-phosphoryl termini, and cleavage of 5'-end-labelled DNA gave rise to fragments bearing 3'-phosphoryl and 3'-'phosphatase-inert' termini in equal proportions. No appreciable amounts of fragments bearing 3'- or 5'-hydroxy termini were detected. This pattern of cleavage products is similar to that observed using the hydroxyl-radical-generating systems, 60Co gamma-irradiation or methidium propyl EDTA:Fe(II), but is dissimilar to that found with the Cu(II):phenanthroline or bleomycin systems. Cu(II):thiol cleavage of DNA fragments containing inserts of repeated dinucleotide sequence showed alternating patterns of relative cleavage intensities within the insert-sequence regions which were not seen in the sequences flanking the insert sequence. The assembled experimental data indicate that a reaction product of the Cu(II):thiol interaction, probably the hydroxyl radical, causes DNA cleavage. The Cu(II):thiol interaction may occur free in solution or via a copper species which is bound non-specifically to DNA. The observed low sequence-dependence of the cleavage reaction probably reflects the nature of the DNA structure itself, the Cu(II):thiol system serving as a structural probe of sequence-dependent structural variations in the DNA structure.

Apparent sequence preference in cleavage of linear B-DNA by the Cu(II):thiol system

Cleavage of a linear tyr T fragment of duplex DNA by Cu(II):thiol combinations occurs with apparent sequence preference. The sequence selectivity was unaffected by the size, chirality or substitution pattern of the monothiol partner, presumably indicating that the Cu(II):RSH system is probing some local conformational/dynamic aspect of the DNA.

Tight binding of a copper (II) phthalocyanine (cuprolinic blue) to DNA

The binding of a cationic phthalocyanine (Cuprolinic Blue) to calf thymus DNA, indicated by the increase in the DNA melting temperature and spectroscopic titration (Kaff greater than 10(7)M-1), was characterised by at least two distinct DNA-bound ligand forms possibly arising from intercalated and externally bound species each with Kaff values in the region 10(7) M-1. Evidence of strong intercalation was provided by gel electrophoresis of plasmid DNA in the presence of Cuprolinic Blue. The anionic phthalocyanine (copper phthalocyanine 3,4',4", 4"'-tetrasulfonic acid) does not bind to DNA by spectral criteria, reflecting electrostatic contributions to binding.