Decreased risk of non-influenza respiratory infection after influenza B virus infection in children.

Previous studies suggest that influenza virus infection may provide temporary non-specific immunity and hence lower the risk of non-influenza respiratory virus infection. In a randomized controlled trial of influenza vaccination, 1 330 children were followed-up in 2009-2011. Respiratory swabs were collected when they reported acute respiratory illness and tested against influenza and other respiratory viruses. We used Poisson regression to compare the incidence of non-influenza respiratory virus infection before and after influenza virus infection. Based on 52 children with influenza B virus infection, the incidence rate ratio (IRR) of non-influenza respiratory virus infection after influenza virus infection was 0.47 (95% confidence interval: 0.27-0.82) compared with before infection. Simulation suggested that this IRR was 0.87 if the temporary protection did not exist. We identified a decreased risk of non-influenza respiratory virus infection after influenza B virus infection in children. Further investigation is needed to determine if this decreased risk could be attributed to temporary non-specific immunity acquired from influenza virus infection.

Effect of metabolic dysfunction-associated steatotic liver disease on BNT162b2 immunogenicity against the severe acute respiratory syndrome coronavirus 2 omicron variant.

BACKGROUND AND AIM: We aimed to investigate the effect of metabolic dysfunction-associated steatotic liver disease (MASLD) on three-dose BNT162b2 immunogenicity to the omicron variant. METHODS: Adult recipients of three doses of BNT162b2 were prospectively recruited between May and December 2021. The serology of the neutralizing antibody by live virus microneutralization (vMN) to the omicron variant was measured at baseline, day 180, and day 360 after the first dose. The primary outcome was seroconversion (vMN titer ≥ 10) at day 360. Exposure of interest was MASLD, defined as hepatic steatosis (controlled attenuation parameter ≥ 248 dB/m on transient elastography) plus at least one of five cardiometabolic risk factors. Subjects with prior COVID-19 were excluded. A multivariable logistic regression model was used to derive the adjusted odds ratio of seroconversion with MASLD by adjusting for age, sex, antibiotic use, and proton pump inhibitor use. RESULTS: One hundred forty-eight BNT162b2 recipients (male: 48 [32.4%]; median age: 51.0 years [interquartile range, IQR: 44.5-57.3]) were recruited. The median time from the first dose to the third dose was 8.5 months (IQR: 7.9-8.9). MASLD subjects had a lower seroconversion rate than non-MASLD ones (89.6% vs 99.0%; P = 0.007). MASLD was the only independent risk factor for seroconversion (adjusted odds ratio: 0.051, 95% confidence interval: 0.002-0.440). Subgroup analysis of immunogenicity at 4 months after the third dose shows significantly lower vMN titer (13.06 [IQR: 7.69-22.20] vs 33.49 [IQR: 24.05-46.53]; P = 0.004) and seroconversion rate (76.9% vs 97.4%; P = 0.016) in MASLD than non-MASLD subjects, but not within 4 months from the third dose (vMN titer: 46.87 [IQR: 33.12-66.02] vs 41.86 [IQR: 34.47-50.91], P = 0.240; seroconversion rate: 94.3% vs 100%, P = 0.131). CONCLUSION: Metabolic dysfunction-associated steatotic liver disease was a risk factor for poorer immunogenicity to the omicron variant, with a more pronounced waning effect compared among three-dose BNT162b2 recipients.

The Predictive Value of Gut Microbiota Composition for Sustained Immunogenicity following Two Doses of CoronaVac.

CoronaVac immunogenicity decreases with time, and we aimed to investigate whether gut microbiota associate with longer-term immunogenicity of CoronaVac. This was a prospective cohort study recruiting two-dose CoronaVac recipients from three centres in Hong Kong. We collected blood samples at baseline and day 180 after the first dose and used chemiluminescence immunoassay to test for neutralizing antibodies (NAbs) against the receptor-binding domain (RBD) of wild-type SARS-CoV-2 virus. We performed shotgun metagenomic sequencing performed on baseline stool samples. The primary outcome was the NAb seroconversion rate (seropositivity defined as NAb ≥ 15AU/mL) at day 180. Linear discriminant analysis [LDA] effect size analysis was used to identify putative bacterial species and metabolic pathways. A univariate logistic regression model was used to derive the odds ratio (OR) of seropositivity with bacterial species. Of 119 CoronaVac recipients (median age: 53.4 years [IQR: 47.8-61.3]; male: 39 [32.8%]), only 8 (6.7%) remained seropositive at 6 months after vaccination. Bacteroides uniformis (log10LDA score = 4.39) and Bacteroides eggerthii (log10LDA score = 3.89) were significantly enriched in seropositive than seronegative participants. Seropositivity was associated with B. eggerthii (OR: 5.73; 95% CI: 1.32-29.55; p = 0.022) and B. uniformis with borderline significance (OR: 3.27; 95% CI: 0.73-14.72; p = 0.110). Additionally, B. uniformis was positively correlated with most enriched metabolic pathways in seropositive vaccinees, including the superpathway of adenosine nucleotide de novo biosynthesis I (log10LDA score = 2.88) and II (log10LDA score = 2.91), as well as pathways related to vitamin B biosynthesis, all of which are known to promote immune functions. In conclusion, certain gut bacterial species (B. eggerthii and B. uniformis) and metabolic pathways were associated with longer-term CoronaVac immunogenicity.

Autoantibodies against angiotensin-converting enzyme 2 (ACE2) after COVID-19 infection or vaccination.

Autoantibodies against angiotensin-converting enzyme 2 (ACE2) are frequently reported in patients during coronavirus disease 2019 (COVID-19) with evidence for a pathogenic role in severe infection. However, little is known of the prevalence or clinical significance of ACE2 autoantibodies in late convalescence or following COVID-19 vaccination. In this study, we measured ACE2 autoantibodies in a cohort of 182 COVID-19 convalescent patients, 186 COVID-19 vaccine recipients, and 43 adolescents with post-mRNA vaccine myopericarditis using two ACE2 enzymatic immunoassays (EIAs). ACE2 IgM autoantibody EIA median optical densities (ODs) were lower in convalescent patients than pre-COVID-19 control samples with only 2/182 (1.1%) convalescents testing positive. Similarly, only 3/182 (1.6%) convalescent patients tested positive for ACE2 IgG, but patients with history of moderate-severe COVID-19 tended to have significantly higher median ODs than controls and mild COVID-19 patients. In contrast, ACE2 IgG antibodies were detected in 10/186 (5.4%) COVID-19 vaccine recipients after two doses of vaccination. Median ACE2 IgG EIA ODs of vaccine recipients were higher than controls irrespective of the vaccine platform used (inactivated or mRNA). ACE2 IgG ODs were not correlated with surrogate neutralizing antibody levels in vaccine recipients. ACE2 IgG levels peaked at day 56 post-first dose and declined within 12 months to baseline levels in vaccine recipients. Presence of ACE2 antibodies was not associated with adverse events following immunization including myopericarditis. One convalescent patient with ACE2 IgG developed Guillain-Barre syndrome, but causality was not established. ACE2 autoantibodies are observed in COVID-19 vaccine recipients and convalescent patients, but are likely innocuous.

Satisfaction with government recommended pre-procedural mouth rinses in the mitigation of Covid-19 in Hong Kong SAR: A triple blind randomized controlled clinical trial.

OBJECTIVE: To evaluate satisfaction and acceptability with three pre-procedural mouthrinses recommended by the Government of Hong Kong Special Administrative Region (HKSAR) during the COVID-19 pandemic. MATERIAL AND METHODS: A triple-blind parallel-arm randomised controlled clinical trial was conducted. Following eligibility assessment, participants were block-randomised to the three intervention pre-procedural mouthrinses groups: Povidone-iodine, Hydrogen Peroxide and Chlorhexidine Digluconate. Participants rinsed with one of the mouthrinses assigned prior to any dental treatment. Participants, operators and assessors were blind to the assigned mouthrinses (triple blind). Satisfaction ratings were assessed on a 10 cm visual analogue scale (VAS) and acceptability of the mouthrinses were determined. RESULTS: Following clinical screening, 228 participants were involved in the trial. The mean overall VAS satisfaction was 7.35 (SD 1.68). There was no significant difference in VAS satisfaction ratings among the three groups (p>0.05) nor in between groups. Acceptability of the mouthrinses was high with the vast majority (89.5 %, 204) willing to use the mouthrinses again if pre-procedural mouthrinsing is required. There was no significant difference in acceptability ratings (p>0.05). There were some aspects such as taste and smell that participants commented on (on average, 24.6 %, 56), although no significant difference in prevalence of reports among groups (p>0.05). CONCLUSIONS: There were high rates of satisfaction and acceptability of the HKSAR Government recommended pre-procedural mouthrinses for the mitigation of COVID-19 transmission in the dental setting. There was no significant difference in satisfaction and acceptability rates among the three recommended pre-procedural mouthrinses. CLINICAL RELEVANCE: The high satisfaction and acceptability rates of the HKSAR Government recommended pre-procedural mouthrinses in the mitigation of COVID-19 in this clinical trial lends support for the HKSAR's policy on pre-procedural mouthrinses in the dental setting and this has implications for practice and policy during pandemics.

Human-induced pluripotent stem cell-derived hepatocyte platform in modeling of SARS-CoV-2 infection.

Background and Aim: Currently, SARS-CoV-2 is still spreading rapidly and globally. A large proportion of patients with COVID-19 developed liver injuries. The human-induced pluripotent stem cell (iPSC)-derived hepatocytes recapitulate primary human hepatocytes and have been widely used in studies of liver diseases. Methods: To explore the susceptibility of hepatocytes to SARS-CoV-2, we differentiated iPSCs to functional hepatocytes and tried infecting them with different MOI (1, 0.1, 0.01) of SARS-CoV-2. Results: The iPSC-derived hepatocytes are highly susceptible to virus infection, even at 0.01 MOI. Other than the ancestral strain, iHeps also support the replication of SARS-CoV-2 variants including alpha, beta, theta, and delta. More interestingly, the ACE2 expression significantly upregulated after infection, suggesting a vicious cycle between virus infection and liver injury. Conclusions: The iPSC-derived hepatocytes can support the replication of SARS-CoV-2, and this platform could be used to investigate the SARS-CoV-2 hepatotropism and hepatic pathogenic mechanisms.

Interaction and antiviral treatment of coinfection between SARS-CoV-2 and influenza in vitro.

BACKGROUND: The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has lasted for three years. Coinfection with seasonal influenza may occur resulting in more severe diseases. The interaction between these two viruses for infection and the effect of antiviral treatment remains unclear. METHODS: A SARS-CoV-2 and influenza H1N1 coinfection model on Calu-3 cell line was established, upon which the simultaneous and sequential coinfection was evaluated by comparing the viral load. The efficacy of molnupiravir and baloxavir against individual virus and coinfection were also studied. RESULTS: The replication of SARS-CoV-2 was significantly interfered when the influenza virus was infected simultaneously or in advance (p < 0.05). On the contrary, the replication of the influenza virus was not affected by the SARS-CoV-2. Molnupiravir monotherapy had significant inhibitory effect on SARS-CoV-2 when the concentration reached to 6.25 µM but did not show any significant anti-influenza activity. Baloxavir was effective against influenza within the dosage range and showed significant effect of anti-SARS-CoV-2 at 16 µM. In the treatment of coinfection, molnupiravir had significant effect for SARS-CoV-2 from 6.25 µM to 100 µM and inhibited H1N1 at 100 µM (p < 0.05). The tested dosage range of baloxavir can inhibit H1N1 significantly (p < 0.05), while at the highest concentration of baloxavir did not further inhibit SARS-CoV-2, and the replication of SARS-CoV-2 significantly increased in lower concentrations. Combination treatment can effectively inhibit influenza H1N1 and SARS-CoV-2 replication during coinfection. Compared with molnupiravir or baloxavir monotherapy, combination therapy was more effective in less dosage to inhibit the replication of both viruses. CONCLUSIONS: In coinfection, the replication of SARS-CoV-2 would be interfered by influenza H1N1. Compared with molnupiravir or baloxavir monotherapy, treatment with a combination of molnupiravir and baloxavir should be considered for early treatment in patients with SARS-CoV-2 and influenza coinfection.

Association between Gut Microbiota Composition and Long-Term Vaccine Immunogenicity following Three Doses of CoronaVac.

BACKGROUND: Neutralizing antibody level wanes with time after COVID-19 vaccination. We aimed to study the relationship between baseline gut microbiota and immunogenicity after three doses of CoronaVac. METHODS: This was a prospective cohort study recruiting three-dose CoronaVac recipients from two centers in Hong Kong. Blood samples were collected at baseline and one year post-first dose for virus microneutralization (vMN) assays to determine neutralization titers. The primary outcome was high immune response (defined as with vMN titer ≥ 40). Shotgun DNA metagenomic sequencing of baseline fecal samples identified potential bacterial species and metabolic pathways using Linear Discriminant Analysis Effect Size (LEfSe) analysis. Univariate and multivariable logistic regression models were used to identify high response predictors. RESULTS: In total, 36 subjects were recruited (median age: 52.7 years [IQR: 47.9-56.4]; male: 14 [38.9%]), and 18 had low immune response at one year post-first dose vaccination. Eubacterium rectale (log10LDA score = 4.15, p = 0.001; relative abundance of 1.4% vs. 0, p = 0.002), Collinsella aerofaciens (log10LDA score = 3.31, p = 0.037; 0.39% vs. 0.18%, p = 0.038), and Streptococcus salivarius (log10LDA score = 2.79, p = 0.021; 0.05% vs. 0.02%, p = 0.022) were enriched in low responders. The aOR of high immune response with E. rectale, C. aerofaciens, and S. salivarius was 0.03 (95% CI: 9.56 × 10-4-0.32), 0.03 (95% CI: 4.47 × 10-4-0.59), and 10.19 (95% CI: 0.81-323.88), respectively. S. salivarius had a positive correlation with pathways enriched in high responders like incomplete reductive TCA cycle (log10LDA score = 2.23). C. aerofaciens similarly correlated with amino acid biosynthesis-related pathways. These pathways all showed anti-inflammation functions. CONCLUSION: E. rectale,C. aerofaciens, and S. salivarius correlated with poorer long-term immunogenicity following three doses of CoronaVac.

The impact of vaccine type and booster dose on the magnitude and breadth of SARS-CoV-2-specific systemic and mucosal antibodies among COVID-19 vaccine recipients.

The COVID-19 pandemic has had a major impact on global health and economy, which was significantly mitigated by the availability of COVID-19 vaccines. The levels of systemic and mucosal antibodies against SARS-CoV-2 correlated with protection. However, there is limited data on how vaccine type and booster doses affect mucosal antibody response, and how the breadth of mucosal and systemic antibodies compares. In this cross-sectional study, we compared the magnitude and breadth of mucosal and systemic antibodies in 108 individuals who received either the BNT162b2 (Pfizer) or CoronaVac (SinoVac) vaccine. We found that BNT162b2 (vs CoronaVac) or booster doses (vs two doses) were significantly associated with higher serum IgG levels, but were not significantly associated with salivary IgA levels, regardless of prior infection status. Among non-infected individuals, serum IgG, serum IgA and salivary IgG levels were significantly higher against the ancestral strain than the Omicron BA.2 sublineage, but salivary IgA levels did not differ between the strains. Salivary IgA had the weakest correlation with serum IgG (r = 0.34) compared with salivary IgG (r = 0.63) and serum IgA (r = 0.60). Our findings suggest that intramuscular COVID-19 vaccines elicit a distinct mucosal IgA response that differs from the systemic IgG response. As mucosal IgA independently correlates with protection, vaccine trials should include mucosal IgA as an outcome measure.