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.

Effect of stress on clinical reasoning during simulated ambulatory consultations

BACKGROUND

The goal of this study was to examine the impact of subjective and physiological stress responses on medical students' diagnostic reasoning and communication skills.

METHOD

A prospective randomized quantitative study was undertaken, looking at ambulatory consultations in internal medicine. On the first day (baseline day), volunteer year 6 students (n = 41) participated in a simulated ambulatory consultation with standardized patients (SPs). On the second day (study day), one week later, they were randomly assigned to two groups: a low stress (n = 20) and a high stress (n = 21) simulated ambulatory consultation. Stress was measured using validated questionnaires and salivary cortisol. The SPs assessed the students' reasoning and communication. The students completed assessments of their clinical reasoning after the consultations.

RESULTS

Although stress measures were all significantly higher in the high-stress condition (all p < 0.05), no differences were found in diagnostic accuracy and justification scores. However, correlational analyses revealed a negative correlation between multiple-stress measures and the students' ability to generate arguments for differential diagnoses.

CONCLUSION

Stress was associated with impairments in clinical reasoning, of a nature typically suggestive of premature closure.

YKL-40 (cartilage gp-39) induces proliferative events in cultured chondrocytes and synoviocytes and increases glycosaminoglycan synthesis in chondrocytes

YKL-40 (cartilage gp-39), is a mammalian glycoprotein related in sequence to chitinases. Its function is unknown, but it is thought to be involved in tissue remodeling. Immunocytochemical staining of YKL-40 in guinea pig chondrocytes (GPC), rabbit chondrocytes (RC), and rabbit synoviocytes (RS) was higher in dividing cells than in confluent cells, suggesting a participation of YKL-40 in cell cycle events. As assessed by the MTT assay, YKL-40 at 1.9-7.6 nM had dose-dependent mitogenic activity toward the three cell types. At 7.6 nM, YKL-40 increased the number of cells of 42% in GPC, 75% in RC, and 86% in RS after 72 h. YKL-40 also stimulated total proteoglycan synthesis by chondrocytes in a dose-dependent manner as assessed by Na[35SO4] incorporation and cetylpyridinium chloride precipitation. At 9.4 nM, YKL-40 increased proteoglycan synthesis of 42% in GPC and 58% in RC after 24 h. The growth factor properties of YKL-40 may explain the increased tissue remodeling associated with high levels of YKL-40 in joint diseases, and possibly, in malignant pathologies such as breast cancer or colorectal cancer.

[Cellular changes at the level of the outer enamel epithelium during vascularization of the enamel organ in the rat]

In the albinos rat, at day 20 in utero, the outer epithelial layer of the first molar is depressed by numerous capillaries. The mesenchymal cells of the follicle present cytoplasmic extensions which are in close relationship with the basement lamina of the external epithelial layer with fibrillar material adherent to the basement lamina. The endothelial cells of the capillaries also present cytoplasmic extensions in contact with the basement lamina. At day 21 in utero, the capillaries penetrate deeply into the stellate reticulum. The fact that the epithelium which surrounds the capillaries is separated from the latter by a basement membrane indicates that the vascular penetration induces a very deep invagination of the epithelium and the basement membrane. This vascular penetration could play a role in the transport of precursors towards the secretory ameloblasts. The mesenchymal and endothelial tissues of the capillaries could have an inductive role on the external epithelial layer through the basement membrane, leading to a disorganization of the enamel organ.

[Oral nerve endings in the cat]

The oral nerve endings of the palate, the buccal mucosa and the periodontal ligament of the cat canine were characterized by the presence of a cellular envelope which is the final form of the Henle sheath. The structures described as end-rings in the periodontal ligament are more probably subterminal nervous structures rather then receptors. They are not specific to the ligament. They can be observed in the palate and in the buccal mucosa where, as in the periodontal ligament, mechano-receptors of the Vater-Pacini type can be seen.