Dispersion of SARS-CoV-2 in air surrounding COVID-19-infected individuals with mild symptoms.

Since the beginning of the pandemic, the transmission modes of SARS-CoV-2-particularly the role of aerosol transmission-have been much debated. Accumulating evidence suggests that SARS-CoV-2 can be transmitted by aerosols, and not only via larger respiratory droplets. In this study, we quantified SARS-CoV-2 in air surrounding 14 test subjects in a controlled setting. All subjects had SARS-CoV-2 infection confirmed by a recent positive PCR test and had mild symptoms when included in the study. RT-PCR and cell culture analyses were performed on air samples collected at distances of one, two, and four meters from test subjects. Oronasopharyngeal samples were taken from consenting test subjects and analyzed by RT-PCR. Additionally, total aerosol particles were quantified during air sampling trials. Air viral concentrations at one-meter distance were significantly correlated with both viral loads in the upper airways, mild coughing, and fever. One sample collected at four-meter distance was RT-PCR positive. No samples were successfully cultured. The results reported here have potential application for SARS-CoV-2 detection and monitoring schemes, and for increasing our understanding of SARS-CoV-2 transmission dynamics. Practical implications. In this study, quantification of SARS-CoV-2 in air was performed around infected persons with mild symptoms. Such persons may go longer before they are diagnosed and may thus be a disproportionately important epidemiological group. By correlating viral concentrations in air with behavior and symptoms, we identify potential risk factors for viral dissemination in indoor environments. We also show that quantification of total aerosol particles is not a useful strategy for monitoring SARS-CoV-2 in indoor environments.

Simultaneous Targeting of Multiple Hemagglutinins to APCs for Induction of Broad Immunity against Influenza.

There is a need for vaccines that can confer broad immunity against highly diverse pathogens, such as influenza. The efficacy of conventional influenza vaccines is dependent on accurate matching of vaccines to circulating strains, but slow and limited production capacities increase the probability of vaccine mismatches. In contrast, DNA vaccination allows for rapid production of vaccines encoding novel influenza Ags. The efficacy of DNA vaccination is greatly improved if the DNA-encoded vaccine proteins target APCs. In this study, we have used hemagglutinin (HA) genes from each of six group 1 influenza viruses (H5, H6, H8, H9, H11, and H13), and inserted these into a DNA vaccine format that induces delivery of the HA protein Ags to MHC class II molecules on APCs. Each of the targeted DNA vaccines induced high titers of strain-specific anti-HA Abs. Importantly, when the six HA vaccines were mixed and injected simultaneously, the strain-specific Ab titers were maintained. In addition, the vaccine mixture induced Abs that cross-reacted with strains not included in the vaccine mixture (H1) and could protect mice against a heterosubtypic challenge with the H1 viruses A/Puerto Rico/8/1934 (H1N1) and A/California/07/2009 (H1N1). The data suggest that vaccination with a mixture of HAs could be useful for induction of strain-specific immunity against strains represented in the mixture and, in addition, confer some degree of cross-protection against unrelated influenza strains.

Applying valency-based immuno-selection to generate broadly cross-reactive antibodies against influenza hemagglutinins.

Conserved epitopes shared between virus subtypes are often subdominant, making it difficult to induce broadly reactive antibodies by immunization. Here, we generate a plasmid DNA mix vaccine that encodes protein heterodimers with sixteen different influenza A virus hemagglutinins (HA) representing all HA subtypes except H1 (group 1) and H7 (group 2). Each single heterodimer expresses two different HA subtypes and is targeted to MHC class II on antigen presenting cells (APC). Female mice immunized with the plasmid mix produce antibodies not only against the 16 HA subtypes, but also against non-included H1 and H7. We demonstrate that individual antibody molecules cross-react between different HAs. Furthermore, the mix vaccine induces T cell responses to conserved HA epitopes. Immunized mice are partially protected against H1 viruses. The results show that application of valency-based immuno-selection to diversified antigens can be used to direct antibody responses towards conserved (subdominant) epitopes on viral antigens.

Humoral and cellular immune responses to two and three doses of SARS-CoV-2 vaccines in rituximab-treated patients with rheumatoid arthritis: a prospective, cohort study.

BACKGROUND: In rituximab-treated patients with rheumatoid arthritis, humoral and cellular immune responses after two or three doses of SARS-CoV-2 vaccines are not well characterised. We aimed to address this knowledge gap. METHODS: This prospective, cohort study (Nor-vaC) was done at two hospitals in Norway. For this sub-study, we enrolled patients with rheumatoid arthritis on rituximab treatment and healthy controls who received SARS-CoV-2 vaccines according to the Norwegian national vaccination programme. Patients with insufficient serological responses to two doses (antibody to the receptor-binding domain [RBD] of the SARS-CoV-2 spike protein concentration <100 arbitrary units [AU]/mL) were allotted a third vaccine dose. Antibodies to the RBD of the SARS-CoV-2 spike protein were measured in serum 2-4 weeks after the second and third doses. Vaccine-elicited T-cell responses were assessed in vitro using blood samples taken before and 7-10 days after the second dose and 3 weeks after the third dose from a subset of patients by stimulating cryopreserved peripheral blood mononuclear cells with spike protein peptides. The main outcomes were the proportions of participants with serological responses (anti-RBD antibody concentrations of ≥70 AU/mL) and T-cell responses to spike peptides following two and three doses of SARS-CoV-2 vaccines. The study is registered at ClinicalTrials.gov, NCT04798625, and is ongoing. FINDINGS: Between Feb 9, 2021, and May 27, 2021, 90 patients were enrolled, 87 of whom donated serum and were included in our analyses (69 [79·3%] women and 18 [20·7%] men). 1114 healthy controls were included (854 [76·7%] women and 260 [23·3%] men). 49 patients were allotted a third vaccine dose. 19 (21·8%) of 87 patients, compared with 1096 (98·4%) of 1114 healthy controls, had a serological response after two doses (p<0·0001). Time since last rituximab infusion (median 267 days [IQR 222-324] in responders vs 107 days [80-152] in non-responders) and vaccine type (mRNA-1273 vs BNT162b2) were significantly associated with serological response (adjusting for age and sex). After two doses, 10 (53%) of 19 patients had CD4+ T-cell responses and 14 (74%) had CD8+ T-cell responses. A third vaccine dose induced serological responses in eight (16·3%) of 49 patients, but induced CD4+ and CD8+ T-cell responses in all patients assessed (n=12), including responses to the SARS-CoV-2 delta variant (B.1.617.2). Adverse events were reported in 32 (48%) of 67 patients and in 191 (78%) of 244 healthy controls after two doses, with the frequency not increasing after the third dose. There were no serious adverse events or deaths. INTERPRETATION: This study provides important insight into the divergent humoral and cellular responses to two and three doses of SARS-CoV-2 vaccines in rituximab-treated patients with rheumatoid arthritis. A third vaccine dose given 6-9 months after a rituximab infusion might not induce a serological response, but could be considered to boost the cellular immune response. FUNDING: The Coalition for Epidemic Preparedness Innovations, Research Council of Norway Covid, the KG Jebsen Foundation, Oslo University Hospital, the University of Oslo, the South-Eastern Norway Regional Health Authority, Dr Trygve Gythfeldt og frues forskningsfond, the Karin Fossum Foundation, and the Research Foundation at Diakonhjemmet Hospital.