Estimating SARS-CoV-2 infections and associated changes in COVID-19 severity and fatality

Outpatient Testing for HIV in Italy, 2018-2023-Preliminary Data

HIV testing is crucial towards the control of the Acquired Immune Deficiency Syndrome (AIDS) epidemic. Monitoring trends of human immunodeficiency virus (HIV) testing over time may help interpret the incidence of new HIV diagnoses and effectiveness of HIV testing strategies. We started a research project aimed at assessing testing rates for HIV infection among Italian outpatients in 2018-2023. Numeric data for screening, confirmatory, and monitoring tests obtained by a national register were compared with the numbers of adult residents, newly diagnosed HIV infections, and patients undergoing treatment. The number of screening tests declined from 1,133,377 in 2018 to 889,972 in 2020 and increased to 1,096,822 in 2023. HIV-RNA tests showed a similar pattern, whereas confirmatory immunoblots did not vary significantly over time. The ratio of screening tests to adult residents was higher in North-West (2.87%) and North-East (2.31%) Italy compared to South Italy and the islands (1.47%), indicating that screening should be enhanced in the latter area. We observed differences between the ratio of screening tests and the incidence of newly diagnosed HIV infections by geographic area. Discrepancies in the number of screening and confirmatory tests needed for each new diagnosis suggest repeated testing on people already diagnosed and possible data reporting issues. The monitoring of HIV screening tests at the national and regional levels can provide essential data to interpret trends in HIV epidemiology and plan relevant testing strategies over time.

Association between long-term exposure to air pollutants with breakthrough SARS-CoV-2 infections and antibody responses among COVID-19 vaccinated older adults in Northern Italy

AIMS

To investigate the association between long-term exposure to PM2.5, PM10, NO2 and O3 with SARS-CoV-2 breakthrough infections and COVID-19 vaccine-induced antibody responses in a northern Italian population-based sample of older adults.

METHODS

Within an ongoing prospective population-based study, we followed-up 1326 vaccinated individuals aged 65-83 years, with no prior SARS-CoV-2 infection, for their first positive SARS-CoV-2 swab until December 31st, 2022. We assessed spike IgG antibody levels in most participants (n = 1206). The 2019 annual mean levels of air pollutants derived from combined use of chemical-transport and random-Forest models (spatial resolution: 1Kmq) were individually assigned based on the latest residence address. We estimated multivariable-adjusted associations (per 1 interquartile range increase, IQR) of air pollutants with breakthrough infections using Cox models with time-dependent vaccine exposure; and with percent change in the IgG geometric mean using generalized additive models.

RESULTS

The mean (SD) age was 74.9 ± 4.1 years, and 50% were women. An IQR (1.2 μg/m3) increase in long-term PM2.5 exposure was associated with a 52% increase in breakthrough infection risk following a second vaccine and a 26% increase following a third vaccine. The effect vanished with the further increment of vaccination doses. Associations for NO2 were inconsistent. Ozone was negatively associated with breakthrough infection risk, but this association reversed in bi-pollutant models adjusting for PM2.5. PM2.5 was associated with a -7.3% (-13.9% to -0.2%) reduction in vaccine-induced IgG levels. The reduction became more pronounced as the time delay from vaccination increased, and with adjustment for NO2 co-exposure.

CONCLUSION

In our population of vaccinated older adults, fine particulate matter exposure was independently associated with a higher risk of SARS-CoV-2 breakthrough infection and a lower antibody response, both effects being influenced by timely and repeated vaccination schedule.

Overview of adult immunization in Italy: Successes, lessons learned and the way forward

The exchange of knowledge and best practices in adult immunization are essential to improve vaccination strategies across the European region. Italy has made groundbreaking progress in the field, being one of the first countries to propose a life-course vaccination schedule, broadening the traditional focus on childhood immunization to include adults. All vaccines included in Italy's vaccination schedule are free of charge. Moreover, the country's National Immunization Plan sets clear coverage targets, immunization priorities, and actions to reduce disparities. However, the fragmentation of its National Health System following the constitutional reform of 2001 has led to an increased complexity and regional inequalities regarding immunization. Other challenges the country faces include growing vaccine hesitancy, data gaps and underserved populations. This review describes Italy's adult immunization system, from policy to implementation. The successes, challenges and lessons learned were shared during the first Adult Immunization Board country meeting in Italy, where local experts, healthcare providers, public health representatives, and policymakers engaged in collaborative discussions and shared insights through case studies and presentations (December 2023). These insights are reviewed and discussed in this manuscript.

Confounding amplifies the effect of environmental factors on COVID-19

The global COVID-19 pandemic has severely impacted human health and socioeconomic development, posing an enormous public health challenge. Extensive research has been conducted into the relationship between environmental factors and the transmission of COVID-19. However, numerous factors influence the development of pandemic outbreaks, and the presence of confounding effects on the mechanism of action complicates the assessment of the role of environmental factors in the spread of COVID-19. Direct estimation of the role of environmental factors without removing the confounding effects will be biased. To overcome this critical problem, we developed a Double Machine Learning (DML) causal model to estimate the debiased causal effects of the influencing factors in the COVID-19 outbreaks in Chinese cities. Comparative experiments revealed that the traditional multiple linear regression model overestimated the impact of environmental factors. Environmental factors are not the dominant cause of widespread outbreaks in China in 2022. In addition, by further analyzing the causal effects of environmental factors, it was verified that there is significant heterogeneity in the role of environmental factors. The causal effect of environmental factors on COVID-19 changes with the regional environment. It is therefore recommended that when exploring the mechanisms by which environmental factors influence the spread of epidemics, confounding factors must be handled carefully in order to obtain clean quantitative results. This study offers a more precise representation of the impact of environmental factors on the spread of the COVID-19 pandemic, as well as a framework for more accurately quantifying the factors influencing the outbreak.

Exposure to obinutuzumab does not affect outcomes of SARS-CoV-2 infection in vaccinated patients with newly diagnosed advanced-stage follicular lymphoma

URBAN is a multicentric, ambispective study evaluating the effectiveness and safety of obinutuzumab-based immuno-chemotherapy and maintenance in patients with untreated advanced follicular lymphoma (FL). The study began before the COVID-19 emergency declaration in Italy. It is currently ongoing for follow-up, and the enrolment timeline encompassed different stages of the pandemic, various vaccination roll-out phases and prevalence of SARS-CoV-2 variants. Outcomes of interest of the present sub-analysis included SARS-CoV-2 infection rates and COVID-19-related hospitalizations/deaths. At data cut-off, 86 (28.8%) and 213 patients (71.2%) were treated before and during/after the COVID-19 outbreak respectively; 294 (98.3%) completed the induction, 31 (10.4%) completed maintenance and 170 (56.9%) were still on maintenance. Overall, 245 patients (81.9%) received at least one SARS-CoV-2 vaccine dose: 13.5%, 31.4% and 55.1% received one, two and three doses respectively. We observed a substantial decrease in COVID-19-related mortality rates in pre- versus post-vaccination phases, along with a reduction in COVID-19-related outcomes due to the shift from alpha/delta to omicron variant predominance. No differences emerged between patients given maintenance or not, although the schedule was modified in 65% of cases. To our knowledge, URBAN represents the largest dataset of COVID-19-related outcomes in FL patients extensively exposed to obinutuzumab. ClinicalTrials.gov identifier: NCT04034056.

Incidence and Predictors of Healthcare-Associated Infections in Patients Admitted to a Temporary Intensive Care Unit during the COVID-19 Pandemic Waves: A Two-Year (2021-2023) Retrospective Cohort Study in Rome, Italy

To manage the number of critical COVID-19 patients, Umberto I Teaching Hospital in Rome established a temporary ICU on March 1, 2021. This study investigated the incidence and risk factors of healthcare-associated infections (HAIs) among these patients during various COVID-19 waves. Patients were grouped by admission date according to the dominant SARS-CoV-2 variant prevalent at the time (Alpha, Delta, Omicron BA.1, Omicron BA.2, Omicron BA.5, and Omicron XBB). First-HAI and mortality rates were calculated per 1000 patient-days. Predictors of first-HAI occurrence were investigated using a multivariable Fine-Gray regression model considering death as a competing event. Among 355 admitted patients, 27.3% experienced at least one HAI, and 49.6% died. Patient characteristics varied over time, with older and more complex cases in the later phases, while HAI and mortality rates were higher in the first year. Pathogens responsible for HAIs varied over time, with first Acinetobacter baumannii and then Klebsiella pneumoniae being progressively predominant. Multivariable analysis confirmed that, compared to Alpha, admission during the Omicron BA.1, BA.2, BA.5, and XBB periods was associated with lower hazards of HAI. Despite worsening COVID-19 patient conditions, late-phase HAI rates decreased, likely due to evolving pathogen characteristics, improved immunity, but also better clinical management, and adherence to infection prevention practices. Enhanced HAI prevention in emergency situations is crucial.

Towards the outbreak tail, what is the public opinion about wastewater surveillance in the United States?

National opinions on a wide variety of public health topics can change over time and have highly contextual nuances. This study is a follow-up to prior inquiries into the knowledge of wastewater-based epidemiology, privacy concerns surrounding sample collection, and the use of data acquired, along with privacy awareness from an online survey conducted in the metropolitan United States during the winter of 2023. Mentions of wastewater-surveillance-related terms in the media remained common. Towards the outbreak tail in 2023, public support for surveillance of toxins (91%), diseases (91%), terrorist threats (87%), illicit drugs (70%), prescription medications (69%), and gun residue (60%) remained high. There was less support for surveillance of alcohol consumption (49%), mental illness (46%), healthy eating (37%), and lifestyle behaviors (35%). In terms of geographic scale, most respondents supported citywide surveillance (85%) with markedly lower levels of support for smaller (less anonymous) geographic scales covered by specific locations. Wastewater surveillance does not receive the public pushback that other COVID-19-related health system actors have witnessed. Instead, the public supports the expansion of wastewater surveillance as a standard to complement public health tools in other areas of health protection.

Differences in SARS-CoV-2 antibodies depending on age, blood group, and sex in a Swedish blood donor cohort

This study aimed to describe differences in prevalence and the long-term presence of nucleocapsid antibodies (N-antibodies) elicited by SARS-CoV-2 infection in a Swedish blood donor population not subjected to lockdown. We tested 20,651 blood donor samples for nucleocapsid antibodies from the beginning of March 2020 and 27 months onwards using the Roche Elecsys Anti-SARS-CoV-2 assay. The proportion of positive SARS-CoV-2 antibody samples was determined each week. After the exclusions of one-time donors and subjects with incomplete data, 19,726 samples from 4003 donors remained. Differences in antibody prevalences stratified for age, sex, and blood groups (ABO and RhD) were determined, as well as antibody loss and recovery. Lower antibody prevalence was seen for older donors, blood group AB, and RhD-negative subjects. A significant decrease in antibody titer between the first and the second antibody-positive donation was seen for the whole study group, females, older subjects, blood group O, AB, and RhD-positive subjects. The titer waned below the detection limit in 60 (3.0%) of 1983 N-antibody-positive donors, and for 18 of these donors, a second episode with antibodies was detected. We showed that N-antibodies persist for months or years and that surprisingly few antibody-positive donors lost their antibodies. We also conclude that antibody prevalence in a Swedish population never subject to lockdown did not apparently differ from populations that were subject to stricter regulations.

Complexity and Diversity of the Neurological Spectrum of SARS-CoV-2 over Three Waves of COVID-19

Background/Objectives: SARS-CoV-2 continually mutates, with five identified variants. Many neurological manifestations were observed during the COVID-19 pandemic, with differences between virus variants. The aim of this study is to assess the frequency and characteristics of neurological manifestations during COVID-19 in hospitalized patients over three waves in Poland with comparison and analysis correlation with the course of infection. Methods: This retrospective single-center study included 600 consecutive adults with confirmed COVID-19, hospitalized during 3 waves (pre-Delta, Delta and Omicron) in Poland. Demographic and clinical information and neurological manifestations were collected and compared across three periods. Results: The median age of the study group was 68, lower during the Delta wave. In the Omicron period, the disease severity at admission and inflammatory markers concentration were the lowest. Neurological manifestations were observed in 49%. The most common were altered mentation, headache, myalgia, mood disorder, ischemic stroke and encephalopathy. Smell and taste disturbances (STDs) were less frequent in the Omicron period. Neurological complications were predominant in the pre-Delta and Omicron periods. Ischemic stroke was observed more often in pre-Delta period. Altered mentation was related to higher severity at admission, worse lab test results, higher admission to ICU and mortality, while headache reduced mortality. Pre-existing dementia was related to higher mortality. Conclusions: Neurological manifestations of COVID-19 are frequent, with a lower rate of STDs in the Omicron period and more often cerebrovascular diseases in the pre-Delta period. Headache improves the course of COVID-19, while altered mentation, stroke and neurological comorbidities increase severity and mortality.

Risk of breakthrough infection and hospitalisation after COVID-19 primary vaccination by HIV status in four Italian regions during 2021

BACKGROUND

As of 2024, vaccination remains the main mitigation measure against COVID-19, but there are contradictory results on whether people living with HIV (PLWH) are less protected by vaccines than people living without HIV (PLWoH). In this study we compared the risk of SARS-CoV-2 infection and COVID-19 hospitalisation following full vaccination in PLWH and PLWoH.

METHODS

We linked data from the vaccination registry, the COVID-19 surveillance system and from healthcare/pharmacological registries in four Italian regions. We identified PLWH fully vaccinated (14 days post completion of the primary cycle) and matched them at a ratio of 1:4 with PLWoH by week of vaccine administration, age, sex, region of residence and comorbidities. Follow-up started on January 24, 2021, and lasted for a maximum of 234 days. We used the Kaplan-Meier estimator to calculate the cumulative incidence of infection and COVID-19 hospitalisation in both groups, and we compared risks using risk differences and ratios taking PLWoH as the reference group.

RESULTS

We matched 42,771 PLWH with 171,084 PLWoH. The overall risk of breakthrough infection was similar in both groups with a rate ratio (RR) of 1.10 (95% confidence interval (CI):0.80-1.53). The absolute difference between groups at the end of the study period was 8.28 events per 10,000 person-days in the PLWH group (95%CI:-18.43-40.29). There was a non-significant increase the risk of COVID-19 hospitalisation among PLWH (RR:1.90; 95%CI:0.93-3.32) which corresponds to 6.73 hospitalisations per 10,000 individuals (95%CI: -0.57 to 14.87 per 10,000).

CONCLUSIONS

Our findings suggest PLWH were not at increased risk of breakthrough SARS-CoV-2 infection or COVID-19 hospitalisation following a primary cycle of mRNA vaccination.

Examining potential Long COVID effects through utilization of healthcare resources: a retrospective, population-based, matched cohort study comparing individuals with and without prior SARS-CoV-2 infection

BACKGROUND

A significant proportion of individuals reports persistent clinical manifestations following SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) acute infection. Nevertheless, knowledge of the burden of this condition-often referred to as 'Long COVID'-on the health care system remains limited. This study aimed to evaluate healthcare utilization potentially related to Long COVID.

METHODS

Population-based, retrospective, multi-center cohort study that analyzed hospital admissions and utilization of outpatient visits and diagnostic tests between adults aged 40 years and older recovered from SARS-CoV-2 infection occurred between February 2020 and December 2021 and matched unexposed individuals during a 6-month observation period. Healthcare utilization was analyzed by considering the setting of care for acute SARS-CoV-2 infection [non-hospitalized, hospitalized and intensive care unit (ICU)-admitted] as a proxy for the severity of acute infection and epidemic phases characterized by different SARS-CoV-2 variants. Data were retrieved from regional health administrative databases of three Italian Regions.

RESULTS

The final cohort consisted of 307 994 previously SARS-CoV-2 infected matched with 307 994 uninfected individuals. Among exposed individuals, 92.2% were not hospitalized during the acute infection, 7.3% were hospitalized in a non-ICU ward and 0.5% were admitted to ICU. Individuals previously infected with SARS-CoV-2 (vs. unexposed), especially those hospitalized or admitted to ICU, reported higher utilization of outpatient visits (range of pooled Incidence Rate Ratios across phases; non-hospitalized: 1.11-1.33, hospitalized: 1.93-2.19, ICU-admitted: 3.01-3.40), diagnostic tests (non-hospitalized: 1.35-1.84, hospitalized: 2.86-3.43, ICU-admitted: 4.72-7.03) and hospitalizations (non-hospitalized: 1.00-1.52, hospitalized: 1.87-2.36, ICU-admitted: 4.69-5.38).

CONCLUSIONS

This study found that SARS-CoV-2 infection was associated with increased use of health care in the 6 months following infection, and association was mainly driven by acute infection severity.

Decoding the historical tale: COVID-19 impact on haematological malignancy patients-EPICOVIDEHA insights from 2020 to 2022

Background

The COVID-19 pandemic heightened risks for individuals with hematological malignancies due to compromised immune systems, leading to more severe outcomes and increased mortality. While interventions like vaccines, targeted antivirals, and monoclonal antibodies have been effective for the general population, their benefits for these patients may not be as pronounced.

Methods

The EPICOVIDEHA registry (National Clinical Trials Identifier, NCT04733729) gathers COVID-19 data from hematological malignancy patients since the pandemic's start worldwide. It spans various global locations, allowing comprehensive analysis over the first three years (2020-2022).

Findings

The EPICOVIDEHA registry collected data from January 2020 to December 2022, involving 8767 COVID-19 cases in hematological malignancy patients from 152 centers across 41 countries, with 42% being female. Over this period, there was a significant reduction in critical infections and an overall decrease in mortality from 29% to 4%. However, hospitalization, particularly in the ICU, remained associated with higher mortality rates. Factors contributing to increased mortality included age, multiple comorbidities, active malignancy at COVID-19 onset, pulmonary symptoms, and hospitalization. On the positive side, vaccination with one to two doses or three or more doses, as well as encountering COVID-19 in 2022, were associated with improved survival.

Interpretation

Patients with hematological malignancies still face elevated risks, despite reductions in critical infections and overall mortality rates over time. Hospitalization, especially in ICUs, remains a significant concern. The study underscores the importance of vaccination and the timing of COVID-19 exposure in 2022 for enhanced survival in this patient group. Ongoing monitoring and targeted interventions are essential to support this vulnerable population, emphasizing the critical role of timely diagnosis and prompt treatment in preventing severe COVID-19 cases.

Funding

Not applicable.

The impact of underreported infections on vaccine effectiveness estimates derived from retrospective cohort studies

BACKGROUND

Surveillance data and vaccination registries are widely used to provide real-time vaccine effectiveness (VE) estimates, which can be biased due to underreported (i.e. under-ascertained and under-notified) infections. Here, we investigate how the magnitude and direction of this source of bias in retrospective cohort studies vary under different circumstances, including different levels of underreporting, heterogeneities in underreporting across vaccinated and unvaccinated, and different levels of pathogen circulation.

METHODS

We developed a stochastic individual-based model simulating the transmission dynamics of a respiratory virus and a large-scale vaccination campaign. Considering a baseline scenario with 22.5% yearly attack rate and 30% reporting ratio, we explored fourteen alternative scenarios, each modifying one or more baseline assumptions. Using synthetic individual-level surveillance data and vaccination registries produced by the model, we estimated the VE against documented infection taking as reference either unvaccinated or recently vaccinated individuals (within 14 days post-administration). Bias was quantified by comparing estimates to the known VE assumed in the model.

RESULTS

VE estimates were accurate when assuming homogeneous reporting ratios, even at low levels (10%), and moderate attack rates (<50%). A substantial downward bias in the estimation arose with homogeneous reporting and attack rates exceeding 50%. Mild heterogeneities in reporting ratios between vaccinated and unvaccinated strongly biased VE estimates, downward if cases in vaccinated were more likely to be reported and upward otherwise, particularly when taking as reference unvaccinated individuals.

CONCLUSIONS

In observational studies, high attack rates or differences in underreporting between vaccinated and unvaccinated may result in biased VE estimates. This study underscores the critical importance of monitoring data quality and understanding biases in observational studies, to more adequately inform public health decisions.