Nosocomial outbreak caused by the SARS-CoV-2 Delta variant in a highly vaccinated population, Israel, July 2021

Twenty-Month Monitoring of Humoral Immune Response to BNT162b2 Vaccine: Antibody Kinetics, Breakthrough Infections, and Adverse Effects

BACKGROUND

Vaccination is one of the most effective life-saving medical interventions, and the introduction of SARS-CoV-2 vaccines was intended to prevent the serious implications of COVID-19. The objectives of the study were (i) to observe the humoral immune response to the BNT162b2 vaccine and SARS-CoV-2 infection (mainly breakthrough infections), (ii) to demonstrate the persistence of anti-SARS-CoV-2 antibodies over time in relation to the number of received vaccine doses and the course of infection, and (iii) to determine the adverse effects after primary vaccine doses.

METHODS

To assess the humoral response, IgG and IgA anti-S1 antibodies were quantified by ELISA assays. In total, the tests were carried out seven times in almost two years.

RESULTS

We demonstrated strong immunogenicity (compared to levels before primary vaccination, 150- and 20-fold increases in IgG and IgA, respectively) of the BNT162b2 vaccine. Over time, we observed a systematic decline in antibody levels, which may have contributed to breakthrough infections. Although they caused seroconversion similar to the booster, antibody levels in such patients fell more rapidly than after re-vaccination. On the other hand, in individuals who did not receive booster(s) and who did not present breakthrough infection, anti-SARS-CoV-2 antibodies returned to pre-vaccination levels after 20 months. The most commonly recognized adverse effects were injection site redness and swelling.

CONCLUSION

Vaccination is highly effective in preventing the most severe outcomes of COVID-19 and should be performed regardless of prior infection. Booster doses significantly enhance anti-SARS-CoV-2 antibody levels and, in contrast to those obtained by breakthrough infection, they remain longer.

Whole-genome sequencing to investigate transmission of SARS-CoV-2 in the acute healthcare setting: a systematic review

BACKGROUND

Whole-genome sequencing (WGS) has been used widely to elucidate transmission of SARS-CoV-2 in acute healthcare settings, and to guide infection, prevention, and control (IPC) responses.

AIM

To systematically appraise available literature, published between January 1st, 2020 and June 30th, 2022, describing the implementation of WGS in acute healthcare settings to characterize nosocomial SARS-CoV-2 transmission.

METHODS

Searches of the PubMed, Embase, Ovid MEDLINE, EBSCO MEDLINE, and Cochrane Library databases identified studies in English reporting the use of WGS to investigate SARS-CoV-2 transmission in acute healthcare environments. Publications involved data collected up to December 31st, 2021, and findings were reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

FINDINGS

In all, 3088 non-duplicate records were retrieved; 97 met inclusion criteria, involving 62 outbreak analyses and 35 genomic surveillance studies. No publications from low-income countries were identified. In 87/97 (90%), WGS supported hypotheses for nosocomial transmission, while in 46 out of 97 (47%) suspected transmission events were excluded. An IPC intervention was attributed to the use of WGS in 18 out of 97 (18%); however, only three (3%) studies reported turnaround times ≤7 days facilitating near real-time IPC action, and none reported an impact on the incidence of nosocomial COVID-19 attributable to WGS.

CONCLUSION

WGS can elucidate transmission of SARS-CoV-2 in acute healthcare settings to enhance epidemiological investigations. However, evidence was not identified to support sequencing as an intervention to reduce the incidence of SARS-CoV-2 in hospital or to alter the trajectory of active outbreaks.

Nosocomial outbreak in a respiratory ward caused by the SARS-CoV-2 Omicron BA 5.2.1 subvariant associated with non-severe illness in vaccinated patients

In this short report, we describe an outbreak of COVID-19 caused by Omicron subvariant BA.5.2.1 in highly vaccinated patients in a respiratory ward in a large acute general hospital in North West London, United Kingdom. The attack rate was high (14/33 (42%)) but the clinical impact was relatively non-severe including in patients who were at high risk of severe COVID-19. Twelve of fourteen patients had COVID-19 vaccinations. There was only one death due to COVID-19 pneumonitis. The findings of this outbreak investigation suggest that while the transmissibility of Omicron BA.5.2.1 subvariant is high, infections caused by this strain are non-severe in vaccinated patients, even if they are at high risk of severe COVID-19 infection.

Assessment of Hospital-Onset SARS-CoV-2 Infection Rates and Testing Practices in the US, 2020-2022

Importance

Characterizing the scale and factors associated with hospital-onset SARS-CoV-2 infections could help inform hospital and public health policies regarding prevention and surveillance needs for these infections.

Objective

To evaluate associations of hospital-onset SARS-CoV-2 infection rates with different periods of the COVID-19 pandemic, hospital characteristics, and testing practices.

Design, Setting, and Participants

This cohort study of US hospitals reporting SARS-CoV-2 testing data in the PINC AI Healthcare Database COVID-19 special release files was conducted from July 2020 through June 2022. Data were collected from hospitals that reported at least 1 SARS-CoV-2 reverse transcription-polymerase chain reaction or antigen test during hospitalizations discharged that month. For each hospital-month where the hospital reported sufficient data, all hospitalizations discharged in that month were included in the cohort. SARS-CoV-2 viral tests and results reported in the microbiology files for all hospitalizations in the study period by discharge month were identified. Data analysis was conducted from September 2022 to March 2023.

Exposure

Hospitalizations discharged in an included hospital-month.

Main Outcomes and Measures

Multivariable generalized estimating equation negative-binomial regression models were used to assess associations of monthly rates of hospital-onset SARS-CoV-2 infections per 1000 patient-days (defined as a first positive SARS-CoV-2 test during after hospitalization day 7) with the phase of the pandemic (defined as the predominant SARS-CoV-2 variant in circulation), admission testing rates, and hospital characteristics (hospital bed size, teaching status, urban vs rural designation, Census region, and patient distribution variables).

Results

A total of 5687 hospital-months from 288 distinct hospitals were included, which contributed 4 421 268 hospitalization records. Among 171 564 hospitalizations with a positive SARS-CoV-2 test, 7591 (4.4%) were found to be hospital onset and 6455 (3.8%) were indeterminate onset. The mean monthly hospital-onset infection rate per 1000 patient-days was 0.27 (95 CI, 0.26-0.29). Hospital-onset infections occurred in 2217 of 5687 hospital-months (39.0%). The monthly percentage of discharged patients tested for SARS-CoV-2 at admission varied; 1673 hospital-months (29.4%) had less than 25% of hospitalizations tested at admission; 2199 hospital-months (38.7%) had 25% to 50% of all hospitalizations tested, and 1815 hospital months (31.9%) had more than 50% of all hospitalizations tested at admission. Postadmission testing rates and community-onset infection rates increased with admission testing rates. In multivariable models restricted to hospital-months testing at least 25% of hospitalizations at admission, a 10% increase in community-onset SARS-CoV-2 infection rate was associated with a 178% increase in the hospital-onset infection rate (rate ratio, 2.78; 95% CI, 2.52-3.07). Additionally, the phase of the COVID-19 pandemic, the admission testing rate, Census region, and bed size were all significantly associated with hospital-onset SARS-CoV-2 infection rates.

Conclusions and Relevance

In this cohort study of hospitals reporting SARS-CoV-2 infections, there was an increase of hospital-onset SARS-CoV-2 infections when community-onset infections were higher, indicating a need for ongoing and enhanced surveillance and prevention efforts to reduce in-hospital transmission of SARS-CoV-2 infections, particularly when community-incidence of SARS-CoV-2 infections is high.

Nosocomial outbreak of SARS-CoV-2 delta variant among vaccinated healthcare workers and immunocompromised patients on a solid-organ transplant unit: Complexities of an epidemiologic and genomic investigation

In September 2021, a cluster of 6 patients with nosocomial coronavirus disease 2019 (COVID-19) were identified in a transplant unit. A visitor and 11 healthcare workers also tested positive for severe acute respiratory coronavirus virus 2 (SARS-CoV-2). Genomic sequencing identified 3 separate introductions of SARS-CoV-2 with related transmission among the identified patients and healthcare workers.

Healthcare costs for hospitalized COVID-19 patients in a Japanese university hospital: a cross-sectional study

BACKGROUND

A health-economic evaluation related to COVID-19 is urgently needed to allocate healthcare resources efficiently; however, relevant medical cost data in Japan concerning COVID-19 are scarce.

METHODS

This cross-sectional study investigated the healthcare cost for hospitalized COVID-19 patients in 2021 at Keio University Hospital. We calculated the healthcare costs during hospitalization using hospital claims data and investigated the variables significantly related to the healthcare cost with multivariable analysis.

RESULTS

The median healthcare cost per patient for the analyzed 330 patients was Japanese yen (JPY) 1,304,431 (US dollars ~ 11,871) (interquartile range: JPY 968,349-1,954,093), and the median length of stay was 10 days. The median healthcare cost was JPY 798,810 for mild cases; JPY 1,113,680 for moderate I cases; JPY 1,643,909 for moderate II cases; and JPY 6,210,607 for severe cases. Healthcare costs increased by 4.0% for each additional day of hospitalization; 1.26 times for moderate I cases, 1.64 times for moderate II cases, and 1.84 times for severe cases compared to mild cases; and 2.05 times for cases involving ICU stay compared to those not staying in ICU.

CONCLUSIONS

We clarified the healthcare cost for hospitalized COVID-19 patients by severity in a Japanese university hospital. These costs contribute as inputs for forthcoming health economic evaluations for strategies for preventing and treating COVID-19.

IgG4 Antibodies Induced by Repeated Vaccination May Generate Immune Tolerance to the SARS-CoV-2 Spike Protein

Less than a year after the global emergence of the coronavirus SARS-CoV-2, a novel vaccine platform based on mRNA technology was introduced to the market. Globally, around 13.38 billion COVID-19 vaccine doses of diverse platforms have been administered. To date, 72.3% of the total population has been injected at least once with a COVID-19 vaccine. As the immunity provided by these vaccines rapidly wanes, their ability to prevent hospitalization and severe disease in individuals with comorbidities has recently been questioned, and increasing evidence has shown that, as with many other vaccines, they do not produce sterilizing immunity, allowing people to suffer frequent re-infections. Additionally, recent investigations have found abnormally high levels of IgG4 in people who were administered two or more injections of the mRNA vaccines. HIV, Malaria, and Pertussis vaccines have also been reported to induce higher-than-normal IgG4 synthesis. Overall, there are three critical factors determining the class switch to IgG4 antibodies: excessive antigen concentration, repeated vaccination, and the type of vaccine used. It has been suggested that an increase in IgG4 levels could have a protecting role by preventing immune over-activation, similar to that occurring during successful allergen-specific immunotherapy by inhibiting IgE-induced effects. However, emerging evidence suggests that the reported increase in IgG4 levels detected after repeated vaccination with the mRNA vaccines may not be a protective mechanism; rather, it constitutes an immune tolerance mechanism to the spike protein that could promote unopposed SARS-CoV2 infection and replication by suppressing natural antiviral responses. Increased IgG4 synthesis due to repeated mRNA vaccination with high antigen concentrations may also cause autoimmune diseases, and promote cancer growth and autoimmune myocarditis in susceptible individuals.

Dynamic Evolution of Humoral and T-Cell Specific Immune Response to COVID-19 mRNA Vaccine in Patients with Multiple Sclerosis Followed until the Booster Dose

This study characterizes antibody and T-cell immune responses over time until the booster dose of COronaVIrus Disease 2019 (COVID-19) vaccines in patients with multiple sclerosis (PwMS) undergoing different disease-modifying treatments (DMTs). We prospectively enrolled 134 PwMS and 99 health care workers (HCWs) having completed the two-dose schedule of a COVID-19 mRNA vaccine within the last 2-4 weeks (T0) and followed them 24 weeks after the first dose (T1) and 4-6 weeks after the booster (T2). PwMS presented a significant reduction in the seroconversion rate and anti-receptor-binding domain (RBD)-Immunoglobulin (IgG) titers from T0 to T1 (p < 0.0001) and a significant increase from T1 to T2 (p < 0.0001). The booster dose in PwMS showed a good improvement in the serologic response, even greater than HCWs, as it promoted a significant five-fold increase of anti-RBD-IgG titers compared with T0 (p < 0.0001). Similarly, the T-cell response showed a significant 1.5- and 3.8-fold increase in PwMS at T2 compared with T0 (p = 0.013) and T1 (p < 0.0001), respectively, without significant modulation in the number of responders. Regardless of the time elapsed since vaccination, most ocrelizumab- (77.3%) and fingolimod-treated patients (93.3%) showed only a T-cell-specific or humoral-specific response, respectively. The booster dose reinforces humoral- and cell-mediated-specific immune responses and highlights specific DMT-induced immune frailties, suggesting the need for specifically tailored strategies for immune-compromised patients to provide primary prophylaxis, early SARS-CoV-2 detection and the timely management of COVID-19 antiviral treatments.

Superspreading potentials of SARS-CoV-2 Delta variants across different contact settings in Eastern China: A retrospective observational study

OBJECTIVES

As the genetic variants of SARS-CoV-2 continuously pose threats to global health, evaluating superspreading potentials of emerging genetic variants is of importance for region-wide control of COVID-19 outbreaks.

METHODS

By using detailed epidemiological contact tracing data of test-positive COVID-19 cases collected between July and August 2021 in Nanjing and Yangzhou, China, we assessed the superspreading potential of outbreaks seeded by SARS-CoV-2 Delta variants. The transmission chains and case-clusters were constructed according to the individual-based surveillance data. We modelled the disease transmission as a classic branching process with transmission heterogeneity governed by negative binomial models. Subgroup analysis was conducted by different contact settings and age groups.

RESULTS

We reported a considerable heterogeneity in the contact patterns and transmissibility of Delta variants in eastern China. We estimated an expected 14% (95% CI: 11-16%) of the most infectious cases generated 80% of the total transmission.

CONCLUSIONS

Delta variants demonstrated a significant potential of superspreading under strict control measures and active COVID-19 detecting efforts. Enhancing the surveillance on disease transmissibility especially in high-risk settings, along with rapid contact tracing and case isolations would be one of the key factors to mitigate the epidemic caused by the emerging genetic variants of SARS-CoV-2.

A 16-month longitudinal investigation of risk and protective factors for mental health outcomes throughout three national lockdowns and a mass vaccination campaign: Evidence from a weighted Israeli sample during COVID-19

BACKGROUND

COVID-19 is an ongoing global crisis, with a multitude of factors that affect mental health worldwide. We explored potential predictors for the emergence and maintenance of depression, anxiety, and posttraumatic stress symptoms (PTSS) in the general population in Israel.

METHODS

Across the span of 16 months, 2478 people completed a repeated self-report survey which inquired psychiatric symptoms and pandemic related stress factors (PRSF). We applied mixed-effects models to assess how each stressor contributes to depression, anxiety and PTSS at each time point, and longitudinally assessed participants who completed at least two consecutive surveys (n = 400). We weighted our sample to increase representativeness of the population.

RESULTS

Fatigue was the strongest predictor for depression, anxiety and PTSS at all time points, and predicted deterioration overtime. Financial concerns associated with depression and anxiety at all time points, and with their deterioration overtime. Health related concerns were uniquely associated with anxiety and PTSS at all time points and their deterioration, but not with depression. Improvement in sense of protection overtime associated with decrease in depression and anxiety. Hesitancy towards vaccination was associated to higher financial concerns and lower sense of protection by the authorities.

CONCLUSIONS

Our findings accentuate the multitude of risk factors for psychiatric morbidity during COVID-19, and the centrality of fatigue in determining mental health outcomes.

Environmental Dissemination of SARS-CoV-2 in a University Hospital during the COVID-19 5th Wave Delta Variant Peak in Castile-León, Spain

The dominant SARS-CoV-2 Delta variant (B.1.617.2) became the main circulating variant among countries by mid 2021. Attention was raised to the increased risk of airborne transmission, leading to nosocomial outbreaks even among vaccinated individuals. Considering the increased number of COVID-19 hospital admissions fueled by the spread of the variant, with Spain showing the highest COVID-19 rates in mainland Europe by July 2021, the aim of this study was to assess SARS-CoV-2 environmental contamination in different areas of a University Hospital in the region of Castile-León, Spain, during the peak of the 5th wave of COVID-19 in the country (July 2021). Air samples were collected from sixteen different areas of the Hospital using a Coriolis® μ air sampler. Surface samples were collected in these same areas using sterile flocked plastic swabs. RNA extraction followed by a one-step RT-qPCR were performed for detection of SARS-CoV-2 RNA. Of the 21 air samples, only one was positive for SARS-CoV-2 RNA, from the emergency waiting room. Of the 40 surface samples, 2 were positive for SARS-CoV-2 RNA, both from the microbiology laboratory. These results may be relevant for risk assessment of nosocomial infection within healthcare facilities, thus helping prevent and minimize healthcare staff's exposure to SARS-CoV-2, reinforcing the importance of always wearing appropriate and well-fit masks at all times and proper PPE when in contact with infected patients.

A two-ward acute care hospital outbreak of SARS-CoV-2 delta variant including a point-source outbreak associated with the use of a mobile vital signs cart and sub-optimal doffing of personal protective equipment

BACKGROUND

The arrival of the Delta variant of SARS-CoV-2 was associated with increased transmissibility and illness of greater severity. Reports of nosocomial outbreaks of Delta variant COVID-19 in acute care hospitals have been described but control measures varied widely.

AIM

Epidemiological investigation of a linked two-ward COVID-19 Delta variant outbreak was conducted to elucidate its source, risk factors, and control measures.

METHODS

Investigations included epidemiologic analysis, detailed case review serial SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) testing of patients and healthcare workers (HCWs), viral culture, environmental swabbing, HCW-unaware personal protective equipment (PPE) audits, ventilation assessments, and the use of whole genome sequencing (WGS).

FINDINGS

This linked two-ward outbreak resulted in 17 patient and 12 HCW cases, despite an 83% vaccination rate. In this setting, suboptimal adherence and compliance to PPE protocols, suboptimal hand hygiene, multi-bedded rooms, and a contaminated vital signs cart with potential fomite or spread via the hands of HCWs were identified as significant risk factors for nosocomial COVID-19 infection. Sudden onset of symptoms, within 72 h, was observed in 79% of all Ward 2 patients, and 93% of all cases (patients and HCWs) on Ward 2 occurred within one incubation period, consistent with a point-source outbreak. RT-PCR assays showed low cycle threshold (C_T) values, indicating high viral load from environmental swabs including the vital signs cart. WGS results with ≤3 SNP differences between specimens were observed.

CONCLUSION

Outbreaks on both wards settled rapidly, within 3 weeks, using a `back-to-basics' approach without extraordinary measures or changes to standard PPE requirements. Strict adherence to recommended PPE, hand hygiene, education, co-operation from HCWs, including testing and interviews, and additional measures such as limiting movement of patients and staff temporarily were all deemed to have contributed to prompt resolution of the outbreak.

Mandatory vaccinations, the segregation of citizens, and the promotion of inequality in the modern democracy of Greece and other democratic countries in the era of COVID-19

During the COVID-19 pandemic, the Greek authorities enforced a vaccination mandate for healthcare workers (HCWs). At the same time, multiple concerns were raised about the epidemiological profile of Greece in addition to the ethical status of the harsh measures and their impact on employees, organizations, society, and public health. According to the World Health Organization (WHO), considerations regarding the evidence of vaccine safety and effectiveness, necessity, and proportionality should be clearly evaluated by before imposing mandatory vaccination policies. We discuss the issues regarding the mechanics of the transmission and contraction of SARS-CoV-2, the toxicity of COVID-19 vaccines, and the impact of the suspension of HCWs who did not vaccinate versus the potential expected benefits in addition to whether the vaccine mandates were justified considering the overall epidemiological context.

The Association Between Clinical Severity and Incubation Period of SARS-CoV-2 Delta Variants: Retrospective Observational Study

BACKGROUND

As of August 25, 2021, Jiangsu province experienced the largest COVID-19 outbreak in eastern China that was seeded by SARS-CoV-2 Delta variants. As one of the key epidemiological parameters characterizing the transmission dynamics of COVID-19, the incubation period plays an essential role in informing public health measures for epidemic control. The incubation period of COVID-19 could vary by different age, sex, disease severity, and study settings. However, the impacts of these factors on the incubation period of Delta variants remains uninvestigated.

OBJECTIVE

The objective of this study is to characterize the incubation period of the Delta variant using detailed contact tracing data. The effects of age, sex, and disease severity on the incubation period were investigated by multivariate regression analysis and subgroup analysis.

METHODS

We extracted contact tracing data of 353 laboratory-confirmed cases of SARS-CoV-2 Delta variants' infection in Jiangsu province, China, from July to August 2021. The distribution of incubation period of Delta variants was estimated by using likelihood-based approach with adjustment for interval-censored observations. The effects of age, sex, and disease severity on the incubation period were expiated by using multivariate logistic regression model with interval censoring.

RESULTS

The mean incubation period of the Delta variant was estimated at 6.64 days (95% credible interval: 6.27-7.00). We found that female cases and cases with severe symptoms had relatively longer mean incubation periods than male cases and those with nonsevere symptoms, respectively. One-day increase in the incubation period of Delta variants was associated with a weak decrease in the probability of having severe illness with an adjusted odds ratio of 0.88 (95% credible interval: 0.71-1.07).

CONCLUSIONS

In this study, the incubation period was found to vary across different levels of sex, age, and disease severity of COVID-19. These findings provide additional information on the incubation period of Delta variants and highlight the importance of continuing surveillance and monitoring of the epidemiological characteristics of emerging SARS-CoV-2 variants as they evolve.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Outbreak at a College With High Coronavirus Disease 2019 (COVID-19) Vaccination Coverage-Connecticut, August 2021-September 2021

BACKGROUND

During August 2021-September 2021, a Connecticut college experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant outbreak despite high (99%) vaccination coverage, indoor masking policies, and twice-weekly testing. The Connecticut Department of Public Health investigated characteristics associated with infection and phylogenetic relationships among cases.

METHODS

A case was a SARS-CoV-2 infection diagnosed by a viral test during August 2021-September 2021 in a student. College staff provided enrollment and case information. An anonymous online student survey collected demographics, SARS-CoV-2 case and vaccination history, and activities preceding the outbreak. Multivariate logistic regression identified characteristics associated with infection. Phylogenetic analyses compared 115 student viral genome sequences with contemporaneous community genomes.

RESULTS

Overall, 199 of 1788 students (11%) had laboratory-confirmed SARS-CoV-2 infection; most were fully vaccinated (194 of 199, 97%). Attack rates were highest among sophomores (72 of 414, 17%) and unvaccinated students (5 of 18, 28%). Attending in-person classes with an infectious student was not associated with infection (adjusted odds ratio [aOR], 1.0; 95% confidence interval [CI], .5-2.2). Compared with uninfected students, infected students were more likely to be sophomores (aOR, 3.3; 95% CI, 1.1-10.7), attend social gatherings before the outbreak (aOR, 2.8; 95% CI, 1.3-6.4), and complete a vaccine series ≥180 days prior (aOR, 5.5; 95% CI, 1.8-16.2). Phylogenetic analyses suggested a common viral source for most cases.

CONCLUSIONS

SARS-CoV-2 infection in this highly vaccinated college population was associated with unmasked off-campus social gatherings, not in-person classes. Students should stay up to date on vaccination to reduce infection.

Explosive COVID-19 outbreak in a German nursing home and the possible role of the air ventilation system

Background

Most COVID-19 outbreaks in nursing homes are explained by transmission of SARS-CoV-2 from nurses or visitors.

Methods and results

We describe an outbreak with 64 of the 67 residents identified as COVID-19 cases within two weeks (34 in nursing block 1, 30 in nursing block 2), at least 32 of them had relevant symptoms of COVID-19. Thirteen of the residents’ deaths were associated with COVID-19. In addition, 27 of approximately 60 staff members were identified as COVID-19 cases, 23 of them had relevant symptoms. In none of the samples from residents or staff was a mutation of SARS-CoV-2 detected. Quarantine of the residents was already in force at the beginning of the outbreak. A common source among the staff was considered to be unlikely because the two nursing home blocks had no staff rotation and the staff had to wear FFP2 masks during contact with residents. Three months after the outbreak the RNA of SARS-CoV-2 was detected on 14 of 39 sampled indoor surfaces of the air ventilation system with Ct values between 34.9 and 41.9, but only at the air supply in the corridor (11 of 24 samples) and the air overflow in the door between the corridor and the residents’ rooms (three of 11 samples) but not at the air exhaust in the residents’ bathrooms.

Conclusions

The air ventilation system and an inversion weather situation three days before the first confirmed case may have enhanced viral spread inside the nursing home assuming that a common source with a high viral load had existed at the time of outbreak.

Six-month humoral and cellular immune response to the third dose of BNT162b2 anti-SARS-CoV-2 vaccine in the patients with solid tumors: a longitudinal cohort study with a focus on the variants of concern

Background

The role and the durability of the immunogenicity of the third dose of vaccine against COVID-19 variants of concern in cancer patients have to be elucidated.

Patients and methods

We have prospectively evaluated the immunogenicity of the third dose of the SARS-CoV-2 BNT162b2 messenger RNA vaccine in triggering both humoral and cell-mediated immune response in patients with solid tumors undergoing active treatment 6 months after the booster. Neutralizing antibody (NT Ab) titers and total anti-spike immunoglobulin G concentrations were measured in serum. Heparinized whole blood samples were used for the SARS-CoV-2 interferon-γ release assay (IGRA).

Results

Six months after the third dose only two patients (2.4%) showed negative spike-specific immunoglobulin G antibody levels (<33.8 BAU/ml). The median level of SARS-CoV-2 NT Abs decreased and only 39/83 (47%) subjects showed maximum levels of NT Abs. T-cellular positive response was observed in 38/61 (62.3%) patients; the highest median level of response was observed 21 days after the third dose (354 mIU/ml, interquartile range 83.3-846.3 mIU/ml). The lowest median level of NT Ab response was observed against the Omicron variant (1 : 10, interquartile range 1 : 10-1 : 40) with a significant reduced rate of responder subjects with respect to the wild-type strain (77.5% versus 95%; P = 0.0022) and Delta variant (77.5% versus 93.7%; P = 0.0053). During the follow-up period, seven patients (8%) had a confirmed post-vaccination infection, but none of them required hospitalization or oxygen therapy.

Conclusions

Our work highlights a significant humoral and cellular immune response among patients with solid tumors 6 months after the third BNT162b2 vaccine dose, although a reduction in neutralizing activity against Omicron was observed.

•

Only two patients (2.4%) showed negative spike-specific IgG antibody levels (<33.8 BAU/ml)

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Only 39/83 (47%) subjects showed maximum level of neutralizing antibodies (NT Abs).

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T-cellular positive response was observed in 38/61 (62.3%) analyzed patients.

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The lowest median level of NT Ab response was observed against the Omicron variant.

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Seven patients (8%) had a post-vaccination infection; none of them required hospitalization or oxygen therapy.

Prevention of SARS-CoV-2 and respiratory viral infections in healthcare settings: current and emerging concepts

PURPOSE OF REVIEW

COVID-19 has catalyzed a wealth of new data on the science of respiratory pathogen transmission and revealed opportunities to enhance infection prevention practices in healthcare settings.

RECENT FINDINGS

New data refute the traditional division between droplet vs airborne transmission and clarify the central role of aerosols in spreading all respiratory viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), even in the absence of so-called 'aerosol-generating procedures' (AGPs). Indeed, most AGPs generate fewer aerosols than talking, labored breathing, or coughing. Risk factors for transmission include high viral loads, symptoms, proximity, prolonged exposure, lack of masking, and poor ventilation. Testing all patients on admission and thereafter can identify early occult infections and prevent hospital-based clusters. Additional prevention strategies include universal masking, encouraging universal vaccination, preferential use of N95 respirators when community rates are high, improving native ventilation, utilizing portable high-efficiency particulate air filters when ventilation is limited, and minimizing room sharing when possible.

SUMMARY

Multifaceted infection prevention programs that include universal testing, masking, vaccination, and enhanced ventilation can minimize nosocomial SARS-CoV-2 infections in patients and workplace infections in healthcare personnel. Extending these insights to other respiratory viruses may further increase the safety of healthcare and ready hospitals for novel respiratory viruses that may emerge in the future.

COVID-19 and plasma cells: Is there long-lived protection?

Infection with SARS-CoV-2, the etiology of the ongoing COVID-19 pandemic, has resulted in over 450 million cases with more than 6 million deaths worldwide, causing global disruptions since early 2020. Memory B cells and durable antibody protection from long-lived plasma cells (LLPC) are the mainstay of most effective vaccines. However, ending the pandemic has been hampered by the lack of long-lived immunity after infection or vaccination. Although immunizations offer protection from severe disease and hospitalization, breakthrough infections still occur, most likely due to new mutant viruses and the overall decline of neutralizing antibodies after 6 months. Here, we review the current knowledge of B cells, from extrafollicular to memory populations, with a focus on distinct plasma cell subsets, such as early-minted blood antibody-secreting cells and the bone marrow LLPC, and how these humoral compartments contribute to protection after SARS-CoV-2 infection and immunization.

Humoral response and breakthrough infections with SARS-CoV-2 B.1.617.2 variant in vaccinated maintenance hemodialysis patients

INTRODUCTION

Breakthrough COVID-19 may occur in vaccinated people, and may result from declining vaccine effectiveness or highly transmittable SARS-CoV-2 variants, such as the B.167.2 (delta) variant. We investigated risk factors and outcomes for infection with the delta variant among vaccinated hemodialysis patients.

METHODS

Patients on maintenance hemodialysis who received two doses of the BNT162b2 (Pfizer-BioNTech) vaccine were analysed according to having developed COVID-19 (study group) or not (control group), in a retrospective, observational, comparative study. We compared risk-factors for developing breakthrough COVID-19 and assessed clinical outcomes, including 30-day mortality rates.

RESULTS

Twenty-four cases of breakthrough SARS-CoV-2 infection were compared to 91 controls without infection. Breakthrough infection was associated with chronic immunosuppressive treatment, hematological malignancies, and low antibody levels against SARS-CoV-2 spike protein. All COVID-19 cases occurred at least 5 months after vaccination, and most were caused by the B.1.617.2 variant (at least 23/24 cases). COVID-19 was categorized as severe or critical disease in 11/24 patients (46%), and 54% required hospitalization and COVID-19-directed treatment. The source of infection was nosocomial in 6/24 cases (25%), and healthcare-related in 3/24 (12.5%). Mortality rate was 21%. Overall mortality was significantly higher in patients who developed COVID-19 than in controls (odds ratio for all-cause mortality 7.6, 95% CI 1.4-41, p = 0.002).

CONCLUSIONS

Breakthrough COVID-19 with the B.1.617.2 variant can occur in vaccinated hemodialysis patients and is associated with immunosuppression and weaker humoral response to vaccination. Infections may be nosocomial and result in significant morbidity and mortality.

Innate immune suppression by SARS-CoV-2 mRNA vaccinations: The role of G-quadruplexes, exosomes, and MicroRNAs

The mRNA SARS-CoV-2 vaccines were brought to market in response to the public health crises of Covid-19. The utilization of mRNA vaccines in the context of infectious disease has no precedent. The many alterations in the vaccine mRNA hide the mRNA from cellular defenses and promote a longer biological half-life and high production of spike protein. However, the immune response to the vaccine is very different from that to a SARS-CoV-2 infection. In this paper, we present evidence that vaccination induces a profound impairment in type I interferon signaling, which has diverse adverse consequences to human health. Immune cells that have taken up the vaccine nanoparticles release into circulation large numbers of exosomes containing spike protein along with critical microRNAs that induce a signaling response in recipient cells at distant sites. We also identify potential profound disturbances in regulatory control of protein synthesis and cancer surveillance. These disturbances potentially have a causal link to neurodegenerative disease, myocarditis, immune thrombocytopenia, Bell's palsy, liver disease, impaired adaptive immunity, impaired DNA damage response and tumorigenesis. We show evidence from the VAERS database supporting our hypothesis. We believe a comprehensive risk/benefit assessment of the mRNA vaccines questions them as positive contributors to public health.

Immunogenicity and Reactogenicity of the Booster Dose of COVID-19 Vaccines and Related Factors: A Panel Study from the General Population in Serbia

The Republic of Serbia applied the booster dose of the following COVID-19 vaccines: BNT162b2 mRNA (Pfizer-BioNTech), Sinopharm BBIBP-CorV (Vero Cell®), Gam-COVID-Vac (Sputnik V) and ChAdOk1 nCoV-19 (AstraZeneca). We aimed to examine the immunogenicity and reactogenicity of the booster dose and identify factors related to immune response and adverse events. Panel study, conducted during August and September 2021, included 300 persons receiving the booster dose at the Institute of Public Health of Serbia. Blood samples were taken on the day of receiving the booster dose, and after 7 and 28 days. When applying homologous regimen, the average increase in anti-spike immunoglobulin G was 8782.2 (after 7 days), 1213.9 after 28 days, while 9179.5 (after 7 days) and 16,728.1 after 28 days of heterologous regimen. Sinopharm BBIBP-CorV (p < 0.001) and Sputnik V (p < 0.001), age 65 and over (p = 0.001) and currently smoking (p < 0.001) were independently associated with lower levels of anti-spike immunoglobulin G. Female sex (OR = 1.77; 95%CI = 1.01−3.12), previous COVID-19 infection (OR = 3.62; 95%CI = 1.13−11.63) and adverse events after the second dose (OR = 2.66; 95%CI = 1.33−5.32) were independently associated with intense systemic adverse events 7 days after. Booster dose significantly increased antibodies titers, especially 28 days after heterologous regimen, without a significant increase in reactogenicity.

A SARS-CoV-2 outbreak associated with vaccine breakthrough in an acute care hospital

BACKGROUND

We aimed to analyze an outbreak caused by a vaccine breakthrough infection in a hospital with an active infection control program where 91.9% of health care workers were vaccinated.

METHODS

We investigated a SARS-CoV-2 outbreak between September 9 and October 2, 2021, in a referral teaching hospital in Korea. We retrospectively collected data on demographics, vaccination history, transmission, and clinical features of confirmed coronavirus disease 2019 (COVID-19) in patients, health care workers, and caregivers.

RESULTS

During the outbreak, 94 individuals tested positive for SARS-CoV-2 using reverse transcription-polymerase chain reaction testing. There were infections in 61 health care workers, 18 patients, and 15 caregivers; 74.5% (70/94) were vaccine breakthrough infections. Most transmissions appeared to be caused by three index cases, which accounted for 86.2% (81/94) of transmissions. Forty-seven (58.0%, 47/81) cases were associated with the hospital staff cafeteria and offices located in the basement. Among health care workers and caregivers, only one required oxygen supplementation. In contrast, among patients, there were four fatal cases (22.2%, 4/18), 3 of which were unvaccinated.

CONCLUSIONS

Superspreading infection among fully vaccinated individuals occurred in an acute care hospital while the delta variant was dominant. Given the potential for severe complications, as this outbreak demonstrated, preventive measures including adequate ventilation should be emphasized to minimize transmission in hospitals.

It Takes Two to Tango: How the COVID-19 Vaccination Campaign in Israel Was Framed by the Health Ministry vs. the Television News

Background

The internet has become a major resource in information transfer during COVID-19, and traditional means of communication are digitized and accessible online to the public at large.

Objectives

This study seeks to examine how Israel's two main television news channels (Channel 12 and Channel 13) covered the Covid-19 vaccination campaign, compared to how the Ministry of Health ran the campaign.

Methods

A qualitative study based on triangulation of online content analyses from three different sources: advertising campaigns, social media posts and reports on television news channels. The research sample included 252 reports from the newsrooms of Channel 13 (n = 151) and Channel N12 (n = 101), Israel's two leading news channels, all broadcast between December 1, 2020 and November 30, 2021. The sample also included posts from Israel Ministry of Health Facebook page and advertising campaigns from the Facebook page of the Israel Government Advertising Agency (LAPAM), which constructs advertising campaigns for the MOH (113 items).

Results

The research findings reveal congruence between the way the MOH framed its vaccination campaign and news coverage of the vaccination issue. The vaccination campaign used three primary framing strategies: (1) positive framing (emphasizing the vaccine's advantages and stressing that the vaccine is safe and effective based on cost-benefit calculations and public health perspectives); (2) fear appeal strategy (conveying persuasive messages that seek to arouse fear through threats of impending danger or harm); (3) attribution of responsibility strategy (blaming the unvaccinated and targeting all those who criticized Israel's generic vaccination policy).

Conclusion

As the watchdog of democracy, the news should function as a professional and objective source that criticizes government systems if necessary and strives to uncover the truth throughout the crisis. Public trust, which is so essential during such a crisis, can be achieved only if the news channels provide reports and meaningful journalistic investigations that challenge the system. By doing so, they can help fight conflicts of interest that divert management of the crisis from the professional health field to the political-economic arena.

Nosocomial Outbreak by Delta Variant From a Fully Vaccinated Patient

BACKGROUND

The potential for a nosocomial outbreak of coronavirus disease 2019 (COVID-19) from a fully vaccinated individual is largely unknown.

METHODS

In October 2021, during the time when the delta variant was dominant, a nosocomial outbreak of COVID-19 occurred in two wards in a tertiary care hospital in Seoul, Korea. We performed airflow investigations and whole-genome sequencing (WGS) of the virus.

RESULTS

The index patient developed symptoms 1 day after admission, and was diagnosed with COVID-19 on day 4 post-admission. He was fully vaccinated (ChAdOx1 nCoV-19) 2 months before the diagnosis. Three inpatients and a caregiver in the same room, two inpatients in an adjacent room, two inpatients in rooms remote from the index room, and one nurse on the ward tested positive. Also, two resident doctors who stayed in an on-call room located on the same ward tested positive (although they had no close contact), as well as a caregiver who stayed on an adjacent ward, and a healthcare worker who had casual contact with this caregiver. Samples from five individuals were available for WGS, and all showed ≤ 1 single-nucleotide polymorphism difference. CCTV footage showed that the index case walked frequently in the corridors of two wards. An airflow study showed that the air from the corridor flowed into the resident on-call room, driven by an air circulator that was always turned on.

CONCLUSION

Transmission of severe acute respiratory syndrome coronavirus 2 from a fully vaccinated index occurred rapidly via the wards and on-call room. Care must be taken to not use equipment that can change the airflow.

Biocompatible Films of Calcium Alginate Inactivate Enveloped Viruses Such as SARS-CoV-2

The current pandemic is urgently demanding the development of alternative materials capable of inactivating the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus 2019 (COVID-19) disease. Calcium alginate is a crosslinked hydrophilic biopolymer with an immense range of biomedical applications due to its excellent chemical, physical, and biological properties. In this study, the cytotoxicity and antiviral activity of calcium alginate in the form of films were studied. The results showed that these films, prepared by solvent casting and subsequent crosslinking with calcium cations, are biocompatible in human keratinocytes and are capable of inactivating enveloped viruses such as bacteriophage phi 6 with a 1.43-log reduction (94.92% viral inactivation) and SARS-CoV-2 Delta variant with a 1.64-log reduction (96.94% viral inactivation) in virus titers. The antiviral activity of these calcium alginate films can be attributed to its compacted negative charges that may bind to viral envelopes inactivating membrane receptors.

How to Deal With Vaccine Breakthrough Infection With SARS-CoV-2 Variants

Novel Coronary Pneumonia is the most infectious disease with the highest number of morbidity and mortality in 100 years. Despite aggressive and effective COVID-19 prevention and control measures, countries have been unable to stop its outbreaks. With the widespread use of vaccines, the occurrence of COVID-19 has declined markedly. April 21, 2021, New York scholars reported Vaccine Breakthrough Infections with SARS-CoV-2 Variants, which immediately attracted widespread attention. In this mini-review, we focus on the characteristics of SARS-CoV-2 and its mutant strains and vaccine breakthrough infections. We have found that outbreaks of vaccine-breaking SARS-CoV-2 Delta infections in many countries are primarily the result of declining vaccine-generated antibody titers and relaxed outbreak management measures. For this reason, we believe that the main response to vaccine-breaking infections with the SARS-CoV-2 variant is to implement a rigorous outbreak defense policy and vaccine application. Only by intensifying the current vaccination intensity, gradually improving the vaccine and its application methods, and strengthening non-pharmaceutical measures such as travel restrictions, social distancing, masking and hand hygiene, can the COVID-19 outbreak be fully controlled at an early date.

Sporadic outbreaks of healthcare-associated COVID-19 infection in a highly-vaccinated inpatient population during a community outbreak of the B.1.617.2 variant: The role of enhanced infection-prevention measures

Sporadic clusters of health care-associated COVID-19 infection occurred in a highly vaccinated health care-workers and patient population, over a 3-month period during ongoing community transmission of the B.1.617.2 variant. Enhanced infection-prevention measures and robust surveillance systems, including routine-rostered-testing of all inpatients and staff and usage of N95-respirators in all clinical areas, were insufficient in achieving zero health care-associated transmission. The unvaccinated and immunocompromised remain at-risk and should be prioritized for enhanced surveillance.

Risk Stratification of SARS-CoV-2 Breakthrough Infections Based on an Outbreak at a Student Festive Event

In early 2022, the Coronavirus disease 2019 (COVID-19) remains a global challenge. COVID-19 is caused by an increasing number of variants of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Here, we report an outbreak of SARS-CoV-2 breakthrough infections related to a student festive event with 100 mostly vaccinated guests, which took place in Northern Bavaria, Germany, in October 2021. The data were obtained by retrospective guest interviews. In total, 95 students participated in the study, with 94 being fully vaccinated and 24 reporting infection by the delta variant. Correlation analyses among 15 examined variables revealed that time spent at the event, conversation with the supposed index person, and a homologous viral vector vaccination regime were significant risk factors for infection. Non-significant observations related to higher rates of infection included time since last vaccination, shared use of drinking vessels, and number of individual person-to-person contacts at the event. Our data suggest that a high rate of breakthrough infections with the delta variant occurs if no preventive measures are practiced. To limit infection risk, high-quality testing of participants should be considered a mandatory measure at gatherings, irrespective of the participants’ vaccination status.

Increment of immunogenicity after third dose of a homologous inactivated SARS-CoV-2 vaccine in a large population of patients with autoimmune rheumatic diseases

Objective

To determine the immunogenicity of the third dose of CoronaVac vaccine in a large population of patients with autoimmune rheumatic diseases (ARD) and the factors associated with impaired response.

Methods

Adult patients with ARD and age-balanced/sex-balanced controls (control group, CG) previously vaccinated with two doses of CoronaVac received the third dose at D210 (6 months after the second dose). The presence of anti-SARS-CoV-2 S1/S2 IgG and neutralising antibodies (NAb) was evaluated previously to vaccination (D210) and 30 days later (D240). Patients with controlled disease suspended mycophenolate mofetil (MMF) for 7 days or methotrexate (MTX) for 2 weekly doses after vaccination.

Results

ARD (n=597) and CG (n=199) had comparable age (p=0.943). Anti-S1/S2 IgG seropositivity rates significantly increased from D210 (60%) to D240 (93%) (p<0.0001) in patients with ARD. NAb positivity also increased: 38% (D210) vs 81.4% (D240) (p<0.0001). The same pattern was observed for CG, with significantly higher frequencies for both parameters at D240 (p<0.05). Multivariate logistic regression analyses in the ARD group revealed that older age (OR=0.98, 95% CI 0.96 to 1.0, p=0.024), vasculitis diagnosis (OR=0.24, 95% CI 0.11 to 0.53, p<0.001), prednisone ≥5 mg/day (OR=0.46, 95% CI 0.27 to 0.77, p=0.003), MMF (OR=0.30, 95% CI 0.15 to 0.61, p<0.001) and biologics (OR=0.27, 95% CI 0.16 to 0.46, p<0.001) were associated with reduced anti-S1/S2 IgG positivity. Similar analyses demonstrated that prednisone ≥5 mg/day (OR=0.63, 95% CI 0.44 to 0.90, p=0.011), abatacept (OR=0.39, 95% CI 0.20 to 0.74, p=0.004), belimumab (OR=0.29, 95% CI 0.13 to 0.67, p=0.004) and rituximab (OR=0.11, 95% CI 0.04 to 0.30, p<0.001) were negatively associated with NAb positivity. Further evaluation of COVID-19 seronegative ARD at D210 demonstrated prominent increases in positivity rates at D240 for anti-S1/S2 IgG (80.5%) and NAb (59.1%) (p<0.0001).

Conclusions

We provide novel data on a robust response to the third dose of CoronaVac in patients with ARD, even in those with prevaccination COVID-19 seronegative status. Drugs implicated in reducing immunogenicity after the regular two-dose regimen were associated with non-responsiveness after the third dose, except for MTX.

Trial registration numberNCT04754698.

The Effect of COVID-19 Endemicity on the Mental Health of Health Workers

Objectives

A major surge in COVID-19 cases despite Singapore's high vaccination has strained the health care system in October 2021. Our aim was to assess and compare Healthcare Worker (HCW) mental well-being in 2021 against a previously published cohort in 2020.

Design

Cross-sectional survey study.

Setting and Participants

HCWs from 4 public hospitals and a primary health care system over a 4-week duration in 2021 coinciding with a major surge compared with a similar period in 2020.

Methods

A survey comprising of the Oldenburg Burnout Inventory (OLBI), Hospital Anxiety and Depression Scale (HADS), and Safety Attitudes Questionnaire (SAQ) was distributed via email. Primary endpoints were the proportion meeting OLBI thresholds for both disengagement and exhaustion and being at risk for both Anxiety and Depression using HADS. Multivariate analysis identified significant predictors among demographic, workplace, and SAQ data. Subgroup analysis of overseas HCWs was performed.

Results

We surveyed 1475 HCWs. Significantly more HCWs met primary outcomes using OLBI and HADS than in 2020 (84.1% and 39.6% vs 68.2% and 23.3%, respectively; P < .001). Burnout levels were uniformly high. A HADS score ≥8 in either subscale was significantly associated with meeting burnout thresholds (P < .001). Overseas HCWs (P = .002), South Asian ethnicity (P = .004), preuniversity educational qualifications (P = .026), and longer shift workhours of 8 to <12 (P = .015) and ≥12 (P = .001) were significantly associated with meeting HADS thresholds. Among overseas HCWs (n=407), seeing family more than a year ago was significantly associated with worse OLBI disengagement scores and a greater proportion meeting HADS thresholds vs seeing them within a year or being local HCWs (47.2% vs 37.2% and 35.6%, respectively; P = .001).

Conclusions and Implications

HCW mental health has objectively worsened between 2020 and 2021 in the pandemic’s second year. Avoiding prolonged shifts, adopting preventive mental health strategies, improving patient safety, and attention to HCWs of minority ethnicity, from overseas, and with preuniversity education may help.

Genomic epidemiology of SARS-CoV-2 under an elimination strategy in Hong Kong

Hong Kong employed a strategy of intermittent public health and social measures alongside increasingly stringent travel regulations to eliminate domestic SARS-CoV-2 transmission. By analyzing 1899 genome sequences (>18% of confirmed cases) from 23-January-2020 to 26-January-2021, we reveal the effects of fluctuating control measures on the evolution and epidemiology of SARS-CoV-2 lineages in Hong Kong. Despite numerous importations, only three introductions were responsible for 90% of locally-acquired cases. Community outbreaks were caused by novel introductions rather than a resurgence of circulating strains. Thus, local outbreak prevention requires strong border control and community surveillance, especially during periods of less stringent social restriction. Non-adherence to prolonged preventative measures may explain sustained local transmission observed during wave four in late 2020 and early 2021. We also found that, due to a tight transmission bottleneck, transmission of low-frequency single nucleotide variants between hosts is rare.

Rapid control of hospital-based SARS-CoV-2 Omicron clusters through daily testing and universal use of N95 respirators

The highly contagious SARS-CoV-2 Omicron variant increases risk for nosocomial transmission despite universal masking, admission testing, and symptom screening. We report large increases in hospital-onset infections and 2 unit-based clusters. The clusters rapidly abated after instituting universal N95 respirators and daily testing. Broader use of these strategies may prevent nosocomial transmissions.

Fending off Delta - Hospital measures to reduce nosocomial transmission of COVID-19

Objectives

Following the emergence of the Delta variant of SARS-CoV-2 in Singapore, our hospital experienced a Delta-linked ward cluster. In this study, we review the enhanced strategies in preventing nosocomial transmission of COVID-19 following widespread community transmission of the Delta variant.

Methods

We conducted a cohort study on exposures to unexpected COVID-19 cases for which contact tracing was initiated from June 2021 to October 2021. Strategies evaluated included upgraded personal protective equipment (PPE) and rostered routine testing (RRT) for staff and patients, surveillance of staff with acute respiratory illness (ARI), and expanded quarantining and testing for contacts of identified cases.

Results

From 193 unexpected COVID-19 exposures, 2,573 staff, 542 patients, and 128 visitor contacts were traced. Four staff contacts subsequently had SARS-CoV-2 infection. Two were likely from exposure in community settings, whereas 2 had exposure to the same COVID-19 positive staff in the hospital, forming the only hospital cluster. One inpatient had a nosocomial infection, possibly from visitors. The SARS-CoV-2 detection rate among staff was 0.3% (of 11,200 staff) from biweekly RRT and 2.5% (of 3,675 staff) from ARI surveillance.

Conclusion

Enhanced hospital measures, including upgraded PPE and RRT for staff and patients, staff sickness surveillance, and more rigorous management of contacts of COVID-19 cases, were likely to have reduced nosocomial transmission amid the Delta variant.

New Insights into the Prevention of Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia Caused by Viruses

A fifth or more of hospital-acquired pneumonias may be attributable to respiratory viruses. The SARS-CoV-2 pandemic has clearly demonstrated the potential morbidity and mortality of respiratory viruses and the constant threat of nosocomial transmission and hospital-based clusters. Data from before the pandemic suggest the same can be true of influenza, respiratory syncytial virus, and other respiratory viruses. The pandemic has also helped clarify the primary mechanisms and risk factors for viral transmission. Respiratory viruses are primarily transmitted by respiratory aerosols that are routinely emitted when people exhale, talk, and cough. Labored breathing and coughing increase aerosol generation to a much greater extent than intubation, extubation, positive pressure ventilation, and other so-called aerosol-generating procedures. Transmission risk is proportional to the amount of viral exposure. Most transmissions take place over short distances because respiratory emissions are densest immediately adjacent to the source but then rapidly dilute and diffuse with distance leading to less viral exposure. The primary risk factors for transmission then are high viral loads, proximity, sustained exposure, and poor ventilation as these all increase net viral exposure. Poor ventilation increases the risk of long-distance transmission by allowing aerosol-borne viruses to accumulate over time leading to higher levels of exposure throughout an enclosed space. Surgical and procedural masks reduce viral exposure but do not eradicate it and thus lower but do not eliminate transmission risk. Most hospital-based clusters have been attributed to delayed diagnoses, transmission between roommates, and staff-to-patient infections. Strategies to prevent nosocomial respiratory viral infections include testing all patients upon admission, preventing healthcare providers from working while sick, assuring adequate ventilation, universal masking, and vaccinating both patients and healthcare workers.

Reconstruction of transmission chains of SARS-CoV-2 amidst multiple outbreaks in a geriatric acute-care hospital: a combined retrospective epidemiological and genomic study

Background

There is ongoing uncertainty regarding transmission chains and the respective roles of healthcare workers (HCWs) and elderly patients in nosocomial outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in geriatric settings.

Methods

We performed a retrospective cohort study including patients with nosocomial coronavirus disease 2019 (COVID-19) in four outbreak-affected wards, and all SARS-CoV-2 RT-PCR positive HCWs from a Swiss university-affiliated geriatric acute-care hospital that admitted both Covid-19 and non-Covid-19 patients during the first pandemic wave in Spring 2020. We combined epidemiological and genetic sequencing data using a Bayesian modelling framework, and reconstructed transmission dynamics of SARS-CoV-2 involving patients and HCWs, to determine who infected whom. We evaluated general transmission patterns according to case type (HCWs working in dedicated Covid-19 cohorting wards: HCW_covid; HCWs working in non-Covid-19 wards where outbreaks occurred: HCW_outbreak; patients with nosocomial Covid-19: patient_noso) by deriving the proportion of infections attributed to each case type across all posterior trees and comparing them to random expectations.

Results

During the study period (1 March to 7 May 2020), we included 180 SARS-CoV-2 positive cases: 127 HCWs (91 HCW_covid, 36 HCW_outbreak) and 53 patients. The attack rates ranged from 10% to 19% for patients, and 21% for HCWs. We estimated that 16 importation events occurred with high confidence (4 patients, 12 HCWs) that jointly led to up to 41 secondary cases; in six additional cases (5 HCWs, 1 patient), importation was possible with a posterior probability between 10% and 50%. Most patient-to-patient transmission events involved patients having shared a ward (95.2%, 95% credible interval [CrI] 84.2%-100%), in contrast to those having shared a room (19.7%, 95% CrI 6.7%-33.3%). Transmission events tended to cluster by case type: patient_noso were almost twice as likely to be infected by other patient_noso than expected (observed:expected ratio 2.16, 95% CrI 1.17-4.20, p=0.006); similarly, HCW_outbreak were more than twice as likely to be infected by other HCW_outbreak than expected (2.72, 95% CrI 0.87-9.00, p=0.06). The proportion of infectors being HCW_covid was as expected as random. We found a trend towards a greater proportion of high transmitters (≥2 secondary cases) among HCW_outbreak than patient_noso in the late phases (28.6% vs. 11.8%) of the outbreak, although this was not statistically significant.

Conclusions

Most importation events were linked to HCW. Unexpectedly, transmission between HCW_covid was more limited than transmission between patients and HCW_outbreak. This finding highlights gaps in infection control and suggests the possible areas of improvements to limit the extent of nosocomial transmission.

Funding

This study was supported by a grant from the Swiss National Science Foundation under the NRP78 funding scheme (Grant no. 4078P0_198363).

mRNA COVID-19 Vaccines and Long-Lived Plasma Cells: A Complicated Relationship

mRNA COVID-19 vaccines have hegemonized the world market, and their administration to the population promises to stop the pandemic. However, the waning of the humoral immune response, which does not seem to last so many months after the completion of the vaccination program, has led us to study the molecular immunological mechanisms of waning immunity in the case of mRNA COVID-19 vaccines. We consulted the published scientific literature and from the few articles we found, we were convinced that there is an immunological memory problem after vaccination. Although mRNA vaccines have been demonstrated to induce antigen-specific memory B cells (MBCs) in the human population, there is no evidence that these vaccines induce the production of long-lived plasma cells (LLPCs), in a SARS-CoV-2 virus naïve population. This obstacle, in our point of view, is caused by the presence, in almost all subjects, of a cellular T and B cross-reactive memory produced during past exposures to the common cold coronaviruses. Due to this interference, it is difficult for a vaccination with the Spike protein alone, without adjuvants capable of prolonging the late phase of the generation of the immunological memory, to be able to determine the production of protective LLPCs. This would explain the possibility of previously and completely vaccinated subjects to become infected, already 4-6 months after the completion of the vaccination cycle.

Current Insights Into Respiratory Virus Transmission and Potential Implications for Infection Control Programs : A Narrative Review

Policies to prevent respiratory virus transmission in health care settings have traditionally divided organisms into Droplet versus Airborne categories. Droplet organisms (for example, influenza) are said to be transmitted via large respiratory secretions that rapidly fall to the ground within 1 to 2 meters and are adequately blocked by surgical masks. Airborne pathogens (for example, measles), by contrast, are transmitted by aerosols that are small enough and light enough to carry beyond 2 meters and to penetrate the gaps between masks and faces; health care workers are advised to wear N95 respirators and to place these patients in negative-pressure rooms. Respirators and negative-pressure rooms are also recommended when caring for patients with influenza or SARS-CoV-2 who are undergoing "aerosol-generating procedures," such as intubation. An increasing body of evidence, however, questions this framework. People routinely emit respiratory particles in a range of sizes, but most are aerosols, and most procedures do not generate meaningfully more aerosols than ordinary breathing, and far fewer than coughing, exercise, or labored breathing. Most transmission nonetheless occurs at close range because virus-laden aerosols are most concentrated at the source; they then diffuse and dilute with distance, making long-distance transmission rare in well-ventilated spaces. The primary risk factors for nosocomial transmission are community incidence rates, viral load, symptoms, proximity, duration of exposure, and poor ventilation. Failure to appreciate these factors may lead to underappreciation of some risks (for example, overestimation of the protection provided by medical masks, insufficient attention to ventilation) or misallocation of limited resources (for example, reserving N95 respirators and negative-pressure rooms only for aerosol-generating procedures or requiring negative-pressure rooms for all patients with SARS-CoV-2 infection regardless of stage of illness). Enhanced understanding of the factors governing respiratory pathogen transmission may inform the development of more effective policies to prevent nosocomial transmission of respiratory pathogens.

The Global Epidemic of the SARS-CoV-2 Delta Variant, Key Spike Mutations and Immune Escape

During the COVID-19 pandemic, SARS-CoV-2 variants have emerged and spread worldwide. The Delta (B.1.617.2) variant was first reported in India in October 2020 and was classified as a "variant of concern (VOC)" by the WHO on 11 May, 2021. Compared to the wild-type strain, several studies have shown that the Delta variant is more transmissible and has higher viral loads in infected samples. COVID-19 patients infected with the Delta variant have a higher risk of hospitalization, intensive care unit (ICU) admission, and mortality. The Delta variant is becoming the dominant strain in many countries around the world. This review summarizes and analyses the biological characteristics of key amino acid mutations, the epidemic characteristics, and the immune escape of the Delta variant. We hope to provide scientific reference for the monitoring and prevention measures of the SARS-CoV-2 Delta variant and the development strategy of a second-generation vaccine.