We studied clinical and immunological outcome of Covid-19 in consecutive CLL patients from a well-defined area during month 1–13 of the pandemic. Sixty patients (median age 71 y, range 43–97) were identified. Median CIRS was eight (4–20). Patients had indolent CLL (n = 38), had completed (n = 12) or ongoing therapy (n = 10). Forty-six patients (77%) were hospitalized due to severe Covid-19 and 11 were admitted to ICU. Severe Covid-19 was equally distributed across subgroups irrespective of age, gender, BMI, CLL status except CIRS (p < 0.05). Fourteen patients (23%) died; age ≥75 y was the only significant risk factor (p < 0.05, multivariate analysis with limited power). Comparing month 1–6 vs 7–13 of the pandemic, deaths were numerically reduced from 32% to 18%, ICU admission from 37% to 15% whereas hospitalizations remained frequent (86% vs 71%). Seroconversion occurred in 33/40 patients (82%) and anti-SARS-CoV-2 antibodies were detectable at six and 12 months in 17/22 and 8/11 patients, respectively. Most (13/17) had neutralizing antibodies and 19/28 had antibodies in saliva. SARS-CoV-2-specific T-cells (ELISpot) were detected in 14/17 patients. Covid-19 continued to result in high admission even among consecutive and young early- stage CLL patients. A robust and durable B and/or T cell immunity was observed in most convalescents.

Background: Patients with immunocompromised disorders have mainly been excluded from clinical trials of vaccination against COVID-19. Thus, the aim of this prospective clinical trial was to investigate the safety and efficacy after two doses of BNT162b2 mRNA vaccination in five selected groups of immunocompromised patients and healthy controls. Methods: 539 study subjects (449 patients and 90 controls) were included in the clinical trial. The patients had either primary (n=90), or secondary immunodeficiency disorders due to human immunodeficiency virus infection (n=90), allogeneic hematopoietic stem cell transplantation/chimeric antigen receptor T cell therapy (n=90), solid organ transplantation (SOT) (n=89), or chronic lymphocytic leukemia (CLL) (n=90). The primary endpoint was seroconversion rate two weeks after the second dose. The secondary endpoints were safety and documented SARS-CoV-2 infection. Findings: Adverse events were generally mild, but one case of fatal suspected unexpected serious adverse reaction occurred. 72.2% of the immunocompromised patients seroconverted compared to 100% of the controls (p=0.004). Lowest seroconversion rates were found in the SOT (43.4%) and CLL (63.3%) patient groups with observed negative impact of treatment with mycophenolate mofetil and ibrutinib, respectively. Interpretation: The results showed that the mRNA BNT162b2 vaccine was safe in immunocompromised patients. The rate of seroconversion was substantially lower than in healthy controls, with a wide range of rates and antibody titres among predefined patient groups and subgroups. This clinical trial highlights the need for additional vaccine doses in certain immunocompromised patient groups and/or subgroups to improve immunity.

The COVID‐19 pandemic poses an immense need for accurate, sensitive and high‐throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high‐throughput multiplex bead‐based serological assay.

We evaluated the performance of 11 SARS-CoV-2 antibody tests using a reference set of heat-inactivated samples from 278 unexposed persons and 258 COVID-19 patients, some of whom contributed serial samples. The reference set included samples with a variation in SARS-CoV-2 IgG antibody titers, as determined by an in-house immunofluorescence assay (IFA). The five evaluated rapid diagnostic tests had a specificity of 99.0% and a sensitivity that ranged from 56.3 to 81.6% and decreased with low IFA IgG titers. The specificity was > 99% for five out of six platform-based tests, and when assessed using samples collected ≥ 22 days after symptom onset, two assays had a sensitivity of > 96%. These two assays also detected samples with low IFA titers more frequently than the other assays. In conclusion, the evaluated antibody tests showed a heterogeneity in their performances and only a few tests performed well with samples having low IFA IgG titers, an important aspect for diagnostics and epidemiological investigations.

Background: Declining humoral immunity in COVID-19 patients and possibility of reinfections has raised concern. Mucosal immunity particularly salivary antibodies could be short-lived. However, long-term studies are sparse. Methods: Using a multiplex bead-based array platform, we investigated antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in 256 saliva samples from convalescent patients 1-9 months after symptomatic COVID-19 (n=74, Cohort 1), undiagnosed individuals with self-reported questionnaires (n=147, Cohort 2), and individuals sampled pre-pandemic time (n= 35, Cohort 3). Results: Salivary IgG antibody responses in Cohort 1 (mainly mild COVID-19) were detectable up to 9 month recovery, with high correlations between spike and nucleocapsid specificity. At 9 months, IgG remained in saliva in majority as seen in blood serology. Salivary IgA was rarely detected at this timepoint. In Cohort 2, salivary IgG and IgA responses were significantly associated with recent history of COVID-19 like symptoms. Salivary IgG also tolerated temperature and detergent pre-treatments. Conclusions: Unlike SARS-CoV-2 salivary IgA that appeared short-lived, the specific IgG in saliva appears stable even after mild COVID-19 as noted for blood serology. The non-invasive saliva-based SARS-Cov-2 antibody testing with self-collection at homes may thus serve as a complementary alternative to conventional blood serology.

We evaluated the performance of 11 SARS-CoV-2 antibody tests using a reference set of heat-inactivated samples from 278 unexposed persons and 258 COVID-19 patients, some of whom contributed serial samples. The reference set included samples with a variation in SARS-CoV-2 IgG antibody titers, as determined by an in-house immunofluorescence assay (IFA). The five evaluated rapid diagnostic tests had a specificity of 99.0% and a sensitivity that ranged from 56.3 to 81.6% and decreased with low IFA IgG titers. The specificity was > 99% for five out of six platform-based tests, and when assessed using samples collected ≥ 22 days after symptom onset, two assays had a sensitivity of > 96%. These two assays also detected samples with low IFA titers more frequently than the other assays. In conclusion, the evaluated antibody tests showed a heterogeneity in their performances and only a few tests performed well with samples having low IFA IgG titers, an important aspect for diagnostics and epidemiological investigations.

The COVID‐19 pandemic poses an immense need for accurate, sensitive and high‐throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high‐throughput multiplex bead‐based serological assay.

Background: Amniocentesis (AC) is the most commonly used invasive prenatal test. The aim of this study was to determine which were the most common indications for AC, chromosomal abnormalities in relation to the age of the mother and complications as a result of AC. Methods: This is a retrospective thirteen-year cohort study including pregnant women who underwent AC in the period from 2008 to 2020. Patients were divided into two groups: below and above 35 years of age of mother at the time of AC. Results: During study period 2213 AC were performed, out of which 759 (34.29%) were in mother below, and 1454 (65.70%) above 35 years of age (p < 0.00001). The most common indication for AC in group above 35 years of age was advanced maternal age (93.9%), in group below 35 years of age was familial chromosomal diseases (29.91%). In all indications there is a statistically significant difference between the two age groups of pregnant women, all these indications are more prevalent in the group of pregnant women younger than 35 years (p < 0.00001). The most common chromosomal abnormalities in both groups was Down syndrome from numerical aberrations, and from structural inversion of chromosome 9. Short term complications were spontaneous abortion in 26 (1.17%), missed abortion in 4 (0.18%) and premature rupture of membranes in 4 (0.18%) cases. Conclusion: Advanced maternal age, demonstrated the strongest association with the uptake of AC, trisomy 21 was the most prevalent abnormal finding. Complications of AC are not significant compared to the general population of pregnant women.

Public health strategies to contain the pandemic continue to vary markedly across the world. In Sweden, compared to most advanced economies, social restrictions have primarily relied upon voluntary adherence to a set of recommendations and strict lockdowns have not been enforced. To better understand the development of humoral immunity to SARS-CoV-2 in the Stockholm population before the start of mass vaccinations, healthy blood donors and pregnant women (n=4,100) were sampled at random between 14th March-11th December 2020. All individuals (n=200/sampling week) were screened for anti-SARS-CoV-2 spike (S) trimer- and RBD-specific IgG responses with highly sensitive and specific ELISA assays, and the results were compared with those from historical controls (n=595). Data were modelled using a probabilistic Bayesian framework that considered individual responses to both antigens. We found that after a steep rise at the start of the pandemic, the seroprevalence trajectory increased steadily in approach to the winter second-wave of infections, approaching 15% of all individuals surveyed by 11th December. In agreement with the high transmission rate observed in the Stockholm area, seroprevalence in this cohort of active adults increased during the 9 months from the start of the outbreak, but was far from that required for herd immunity at the end of 2020.

Abstract Serology is critical for understanding pathogen-specific immune responses, but is fraught with difficulty, not least because the strength of antibody (Ab) response varies greatly between individuals and mild infections generally generate lower Ab titers1–3. We used robust IgM, IgG and IgA Ab tests to evaluate anti-SARS-CoV-2 responses in individuals PCR+ for virus RNA (n=105) representing different categories of disease severity, including mild cases. All PCR+ individuals in the study became IgG-positive against pre-fusion trimers of the virus spike (S) glycoprotein, but titers varied greatly. Elevated IgA, IL-6 and neutralizing responses were present in intensive care patients. Additionally, blood donors and pregnant women (n=2,900) sampled throughout the first wave of the pandemic in Stockholm, Sweden, further demonstrated that anti-S IgG titers differed several orders of magnitude between individuals, with an increase of low titer values present in the population at later time points4,5. To improve upon current methods to identify low titers and extend the utility of individual measures6,7, we used our PCR+ individual data to train machine learning algorithms to assign likelihood of past infection. Using these tools that assigned probability to individual responses against S and the receptor binding domain (RBD), we report SARS-CoV-2-specific IgG in 13.7% of healthy donors five months after the peak of spring COVID-19 deaths, when mortality and ICU occupancy in the country due to the virus were at low levels. These data further our understanding of antibody responses to the virus and provide solutions to problems in serology data analysis. Significance statement Antibody testing provides critical clinical and epidemiological information during an emerging disease pandemic. We developed robust SARS-CoV-2 IgM, IgG and IgA antibody tests and profiled COVID-19 patients and exposed individuals throughout the outbreak in Stockholm, Sweden, where full societal lockdown was not employed. As well as elucidating several disease immunophenotypes, our data highlight the challenge of identifying low IgG titer individuals, who comprise a significant proportion of the population following mild/asymptomatic infection, especially as antibody titers wane following peak responses. To provide a solution to this, we used SARS-CoV-2 PCR+ individual data to develop machine learning approaches that assigned likelihood of past infection to blood donors and pregnant women, improving the accuracy and utility of individual and population-level Ab measures.

Background: The aim of this study is to compare the antenatal care, body weight, and weight gain in pregnancy between the adolescent and adult pregnancies and, thus, examine the impact of adolescence on the studied parameters. Methods: This prospective study includes 300 pregnant women who were the patients of University Clinical Center Tuzla, Clinic for Gynecology and Obstetrics from January 2011 to December 2014. The women were divided into two groups: an experimental group consisted of 150 adolescent pregnant women aged 13–19 years and a control group consisted of 150 adult pregnant women aged 20–35 years. The following parameters were analyzed: age of pregnant women, number of antenatal controls in pregnancy, prepregnancy body weight, weight gain in pregnancy, parity, and obstetric history data. Results: A significantly higher number of adolescent pregnant women belongs to a subgroup from one to two examinations during pregnancy (P < 0.000013) and to subgroups from three to five examinations (P < 0.000001). A significantly smaller number of adolescent pregnant women performed their first antenatal control in the first 2 lunar months (P < 0.01). A subgroup with optimal body weight (from 51 to 69 kg) are the most prevalent among adolescent pregnant women (P < 0.000001). A significantly larger number of adolescent pregnant women had an optimal weight gain of 7.8 to 12.99 kg (P < 0.001). Conclusions: The adolescent pregnant women have suboptimal antenatal care, which could lead to adverse maternal and birth outcomes, but have optimal body weight and weight gain during pregnancy.

Aim To investigate clinical and obstetrical characteristics, an outcome and a prognosis for pregnant women with diagnosed and treated genital or extragenital cancer and their newborns. Methods This retrospective cohort study included pregnant and childbearing women with a history of cancer diagnosed before pregnancy during the period between 1 January 2014 and 31 December 2018. Data related to the course of pregnancy and childbirth were collected from medical records (mothers' disease history and partogram). The analysis covered clinical and histopathological characteristics of cancers, type of the treatment (surgery, chemotherapy, radiotherapy), demographic data, obstetric characteristics, comorbidities of women, and outcome of the newborns. Results The study recorded 18 414 deliveries, of which 30 (0.16%) were pregnancies in women who had been diagnosed and treated earlier for genital or extragenital cancer. The average age of the women at the time of delivery was 29.43±5.97 years. There were six (20%) women with genital and 24 (80%) with extragenital cancer. The most frequent extra genital cancer was Hodgkin lymphoma, in eight (26.6%) cases; ovarian cancer was the most frequent genital cancer, in four (13.3%) cases. The average time span from the cancer diagnosis and start of the treatment to the delivery was 59.2±44.4 months (5 years) (range 12 months - 15 years). Two (6.6%) women died. Conclusion Our data demonstrate a favourable obstetric and neonatal outcome for women who have survived cancer.

Antibody responses vary widely between individuals1, complicating the correct classification of low-titer measurements using conventional assay cut-offs. We found all participants in a clinically diverse cohort of SARS-CoV-2 PCR+ individuals (n=105) – and n=33 PCR+ hospital staff – to have detectable IgG specific for pre-fusion-stabilized spike (S) glycoprotein trimers, while 98% of persons had IgG specific for the receptor-binding domain (RBD). However, anti-viral IgG levels differed by several orders of magnitude between individuals and were associated with disease severity, with critically ill patients displaying the highest anti-viral antibody titers and strongest in vitro neutralizing responses. Parallel analysis of random healthy blood donors and pregnant women (n=1,000) of unknown serostatus, further demonstrated highly variable IgG titers amongst seroconverters, although these were generally lower than in hospitalized patients and included several measurements that scored between the classical 3 and 6SD assay cut-offs. Since the correct classification of seropositivity is critical for individual- and population-level metrics, we compared different probabilistic algorithms for their ability to assign likelihood of past infection. To do this, we used tandem anti-S and -RBD IgG responses from our PCR+ individuals (n=138) and a large cohort of historical negative controls (n=595) as training data, and generated an equal-weighted learner from the output of support vector machines and linear discriminant analysis. Applied to test samples, this approach provided a more quantitative way to interpret anti-viral titers over a large continuum, scrutinizing measurements overlapping the negative control background more closely and offering a probability-based diagnosis with potential clinical utility. Especially as most SARS-CoV-2 infections result in asymptomatic or mild disease, these platform-independent approaches improve individual and epidemiological estimates of seropositivity, critical for effective management of the pandemic and monitoring the response to vaccination.

Serological studies are critical for understanding pathogen-specific immune responses and informing public health measures (1,2). By developing highly sensitive and specific trimeric spike (S)-based antibody tests, we report IgM, IgG and IgA responses to SARS-CoV-2 in COVID-19 patients (n=105) representing different categories of disease severity. All patients surveyed were IgG positive against S. Elevated anti-SARS-CoV-2 antibody levels were associated with hospitalization, with IgA titers, increased circulating IL-6 and strong neutralizing responses indicative of intensive care status. Antibody-positive blood donors and pregnant women sampled during the pandemic in Stockholm, Sweden (weeks 14-25), displayed on average lower titers and weaker neutralizing responses compared to patients; however, inter-individual anti-viral IgG titers differed up to 1,000-fold. To provide more accurate estimates of seroprevalence, given the frequency of weak responders and the limitations associated with the dichotomization of a continuous variable (3,4), we used a Bayesian approach to assign likelihood of past infection without setting an assay cut-off. Analysis of blood donors (n=1,000) and pregnant women (n=900) sampled weekly demonstrated SARS-CoV-2-specific IgG in 7.2% (95% Bayesian CI [5.1-9.5]) of individuals two months after the peak of spring 2020 COVID-19 deaths. Seroprevalence in these otherwise healthy cohorts increased steeply before beginning to level-off, following the same trajectory as the Stockholm region deaths over this time period.

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. We systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in a large cohort of unexposed individuals as well as exposed family members and individuals with acute or convalescent COVID-19. Acute phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative family members and individuals with a history of asymptomatic or mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits robust memory T cell responses akin to those observed in the context of successful vaccines, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19 also in seronegative individuals.