Pertussis and parapertussis in children and adults with a persistent cough: an observational study.

PURPOSE: We aimed to determine the prevalence, symptoms and course of pertussis and parapertussis among patients at any age with a cough of unknown aetiology that had lasted for ≥ 7 days and to assess the diagnostic value of the symptoms included in the World Health Organisations' (WHO) clinical case definition of pertussis. METHODS: Patients were enrolled between the 23 April 2012 and 31 December 2014 at 25 general practitioner (GP) centres and three paediatric hospitals. Pertussis was confirmed by culture and/or polymerase chain reaction (PCR) and/or quantitative serology. Parapertussis was confirmed by culture and/or PCR. RESULTS: Altogether, 549 patients were recruited. Of them, 22 (4.0%; 95% CI 2.5-6.0) had pertussis (predominately diagnosed by positive serology 17/22) and 7 (1.3%; 95% CI 0.5-2.6) had parapertussis. Patients with pertussis were more likely to have inspiratory whooping and posttussive emesis than those with a cough of another/unknown aetiology. However, the presence or absence of these two symptoms did not definitively confirm or exclude pertussis. The sensitivity and specificity of the WHO's clinical definition was 0.77 and 0.38, respectively. CONCLUSIONS: The prevalence of pertussis and parapertussis among patients with a persistent cough of unknown aetiology in Estonia is low. As clinical symptoms alone cannot be used to distinguish pertussis, we recommend that laboratory testing for pertussis is performed in all patients with a persistent cough regardless of age.

Use of oral fluid to examine the molecular epidemiology of varicella zoster virus in the United Kingdom and continental Europe.

We investigated oral fluid (OF) as an alternative to sampling of rashes for varicella zoster virus (VZV) genotyping and further characterized VZV clade prevalence in the United Kingdom and Europe. VZV was detected in up to 91% of OF specimens. Paired OF and vesicle fluid samples contained identical VZV clades. While clades 1 and 3 were the most prevalent across the United Kingdom and Europe, in Western Europe, clade 5 viruses were circulating. Viruses from the same outbreak belonged to different clades, but no clade was associated with a severe-disease phenotype. OF is suitable and convenient for large-scale molecular epidemiological studies of VZV.

Antifungal Drug Usage in European Neonatal Units: A Multicenter Weekly Point Prevalence Study.

BACKGROUND: Data on antifungal prescribing in neonatal patients are limited to either single-center or single-country studies or to 1-day recording. Therefore, we assessed antifungal longitudinal usage in neonatal units (NUs) within Europe. METHODS: CALYPSO, a prospective weekly point prevalence study on antifungal drug usage in NUs in 18 hospitals (8 European countries), was conducted in 2020 during a 12-week period. All patients receiving systemic antifungals were included. Ward demographics were collected at the beginning; ward and patient data including indication, risk factors and antifungal regimen were weekly collected prospectively. RESULTS: Among 27 participating NUs, 15 (56%) practiced antifungal prophylaxis for neonates with birth weight <1000 g or <1500 g and additional risk factors. In total, 174 patients received antifungals with a median frequency per week of 10.5% ranging from 6.9% to 12.6%. Indication for antifungal prescribing was prophylaxis in 135/174 (78%) courses and treatment in 22% [39 courses (69% empirical, 10% preemptive, 21% targeted)]. Fluconazole was the most frequent systemic agent used both for prophylaxis (133/135) and treatment (15/39, 39%). Among neonates receiving prophylaxis, the most common risk factors were prematurity (119/135, 88%), mechanical ventilation (109/135, 81%) and central vascular catheters (89/135, 66%). However, gestational age <28 weeks was only recorded in 55/135 (41%) courses and birth weight <1000 g in 48/135 (35%). Most common reason for empirical treatment was late-onset sepsis; all 8 targeted courses were prescribed for invasive candidiasis. CONCLUSION: Antifungal usage in European NUs is driven by prophylaxis and empirical treatment with fluconazole being the most prescribed agent for both indications.

Seroprevalence and levels of IgG antibodies after COVID-19 infection or vaccination.

BACKGROUND: In a country-wide seroprevalence study of COVID-19 in Estonia, we aimed to determine the seroprevalence and the dynamics of IgG against SARS-CoV-2 after vaccination or positive PCR-test. METHODS: Leftover blood samples were selected between 8 February and 25 March 2021, by SYNLAB Estonia from all counties and age groups (0-9, 10-19, 20-59, 60-69, 70-79 and 80-100 years) proportionally to the whole Estonian population and tested for IgG against SARS-CoV-2 spike protein receptor-binding domain (anti-S-RBD IgG) using Abbott SARS-CoV-2 IgG II Quant assay. Antibody levels after positive PCR-test or vaccination were described by exponential increase-decrease models. RESULTS: According to total of 2517 samples, overall seroprevalence (95% confidence interval [CI]) was 20.1% (18.5-21.7%), similar in all age groups, but varied between counties. If individuals vaccinated with the first dose at least 14 d before antibody measurement were assumed to be seronegative, the overall seroprevalence was 15.8% (14.4-17.3%), 4.0-fold larger than the proportion of PCR-confirmed COVID-19 cases. Of seropositive individuals (n = 506) 194 (38.3%; 33.8-43.1%) had not had positive PCR-test or been vaccinated. According to exponential increase-decrease model, the peak of anti-S-RBD IgG in a 52-year-old (median age of PCR-positive and/or vaccinated individuals) was significantly higher after vaccination compared with positive PCR-test (22,082 (12,897-26,875) vs. 6732 (2321-8243) AU/mL), but half-life was similar (26.5 (6.9-46.1) vs. 38.3 (8.2-68.5) d). CONCLUSIONS: One year after the start of COVID-19 pandemic the actual prevalence of infection is still underestimated compared with PCR-confirmed COVID-19 cases. Older compared with younger individuals have lower anti-S-RBD IgG level after vaccination, but similar decline rate.

Long-Term Elevated Inflammatory Protein Levels in Asymptomatic SARS-CoV-2 Infected Individuals.

The clinical features of SARS-CoV-2 infection range from asymptomatic to severe disease with life-threatening complications. Understanding the persistence of immune responses in asymptomatic individuals merit special attention because of their importance in controlling the spread of the infections. We here studied the antibody and T cell responses, and a wide range of inflammation markers, in 56 SARS-CoV-2 antibody-positive individuals, identified by a population screen after the first wave of SARS-CoV-2 infection. These, mostly asymptomatic individuals, were reanalyzed 7-8 months after their infection together with 115 age-matched seronegative controls. We found that 7-8 months after the infection their antibodies to SARS-CoV-2 Nucleocapsid (N) protein declined whereas we found no decrease in the antibodies to Spike receptor-binding domain (S-RBD) when compared to the findings at seropositivity identification. In contrast to antibodies to N protein, the antibodies to S-RBD correlated with the viral neutralization capacity and with CD4+ T cell responses as measured by antigen-specific upregulation of CD137 and CD69 markers. Unexpectedly we found the asymptomatic antibody-positive individuals to have increased serum levels of S100A12, TGF-alpha, IL18, and OSM, the markers of activated macrophages-monocytes, suggesting long-term persistent inflammatory effect associated with the viral infection in asymptomatic individuals. Our results support the evidence for the long-term persistence of the inflammation process and the need for post-infection clinical monitoring of SARS-CoV-2 infected asymptomatic individuals.

Prevalence of SARS-CoV-2 IgG antibodies and their association with clinical symptoms of COVID-19 in Estonia (KoroSero-EST-1 study).

PURPOSE: In Estonia, during the first wave of COVID-19 total number of cases confirmed by PCR was 13.3/10,000, similar in most regions, including capital Tallinn, but in the hotspot of Estonian epidemic, an island Saaremaa, the cumulative incidence was 166.1/10,000. We aimed to determine the prevalence of SARS-CoV-2 IgG antibodies in these two regions, symptoms associated with infection and factors associated with antibody concentrations. METHODS: Participants were selected using stratified (formed by age decades) random sampling and recruited by general practitioners. IgG or neutralizing antibodies were determined from sera by four assays. Symptoms associated with seropositivity were analyzed by multiple correspondence analysis, antibody concentrations by multiple linear regression. RESULTS: Total of 3608 individual were invited and 1960 recruited from May 8 to July 31, 2020. Seroprevalence was 1.5% (95% confidence interval (CI) 0.9-2.5) and 6.3% (95% CI 5.0-7.9), infection fatality rate 0.1% (95% CI 0.0-0.2) and 1.3% (95% CI 0.4-2.1) in Tallinn and Saaremaa, respectively. Of seropositive subjects 19.2% (14/73) had acute respiratory illness. Fever, diarrhea and the absence of cough and runny nose were associated with seropositivity in individuals aged 50 or more years. IgG, but not neutralizing antibodies concentrations were higher if fever, difficulty breathing, shortness of breath, chest pain or diarrhea was present, or hospitalization required. CONCLUSION: Similarly to other European countries the seroprevalence of SARS-CoV-2 in Estonia was low even in the hotspot region Saaremaa suggesting that majority of population is susceptible to SARS-CoV-2. Focusing only on respiratory symptoms may delay accurate diagnosis of SARS-CoV-2 infection.

Dynamics of pertussis toxin IgG after symptomatic pertussis in children and adults.

BACKGROUND AND AIM: The knowledge of dynamics of pertussis toxin (PT)-IgG after pertussis and the appropriate diagnostic cut-off value is limited. We aimed to describe the dynamics of PT-IgG in children and adults up to three years after symptomatic pertussis. METHODS: Patients with persistent cough of unknown aetiology were prospectively enrolled 2012-2014. Pertussis was confirmed by culture, PCR and/or serology. The follow-up samples were taken 4-6 weeks, 1, 2 and 3 years after enrolment. PT-IgG kinetics was described by biexponential model. RESULTS: Pertussis was diagnosed in 22 patients [median (IQR) age 17.7 (8.4-38.6) years]. Adults compared with children had higher peak of the PT-IgG 397 (IQR 374-518) vs 292 (200-363), p = 0.007, longer time to reach peak PT-IgG 16.4 (IQR 15.6-16.8) days vs 13.3 (13.2-13.4) days, p=<0.001 and shorter PT-IgG half-life 24 days (IQR 20-40) and 364 days (IQR 359-486) p < 0.001. CONCLUSION: After symptomatic pertussis, adults and children have different dynamics of PT-IgG. Clinical trial registry: Not applicable.

Evaluation of SARS-CoV-2 IgG antibody response in PCR positive patients: Comparison of nine tests in relation to clinical data.

SARS-CoV-2 antibody tests are available in various formats, detecting different viral target proteins and antibody subclasses. The specificity and sensitivity of SARS-CoV-2 antibody tests are known to vary and very few studies have addressed the performance of these tests in COVID-19 patient groups at different time points. We here compared the sensitivity and specificity of seven commercial (SNIBE, Epitope, Euroimmun, Roche, Abbott, DiaSorin, Biosensor) and two in-house LIPS assays (LIPS N and LIPS S-RBD) IgG/total Ab tests in serum samples from 97 COVID-19 patients and 100 controls, and correlated the results with the patients' clinical data and the time-point the test was performed. We found a remarkable variation in the sensitivity of antibody tests with the following performance: LIPS N (91.8%), Epitope (85.6%), Abbott and in-house LIPS S-RBD (both 84.5%), Roche (83.5%), Euroimmun (82.5%), DiaSorin (81.4%), SNIBE (70.1%), and Biosensor (64.9%). The overall agreement between the tests was between 71-95%, whereas the specificity of all tests was within 98-100%. The correlation with patients' clinical symptoms score ranged from strongest in LIPS N (ρ = 0.41; p<0.001) to nonsignificant in LIPS S-RBD. Furthermore, the time of testing since symptom onset had an impact on the sensitivity of some tests. Our study highlights the importance to consider clinical symptoms, time of testing, and using more than one viral antigen in SARS-CoV-2 antibody testing. Our results suggest that some antibody tests are more sensitive for the detection of antibodies in early stage and asymptomatic patients, which may explain the contradictory results of previous studies and should be taken into consideration in clinical practice and epidemiological studies.

Estimated and reported incidence of pertussis in Estonian adults: A seroepidemiological study.

OBJECTIVES: Rates of pertussis immunisation among children in Estonia are high (∼95%), but pertussis is still the most common vaccine preventable childhood disease. Adults are suspected to be sources of pertussis in children. We aimed to measure pertussis toxin (PT) IgG in adults to estimate pertussis infection activity and compare estimated and reported pertussis incidences. METHODS: In a cross-sectional serosurvey, consecutive leftover blood sera (n=3327) from subjects aged 20-99 years old were collected at Quattromed HTI laboratories between the 7th January and 27th February 2013. Anti-PT IgG concentration was measured by ELISA (Euroimmun, Lübeck, Germany). Estimated annual pertussis incidence was calculated for 10-year age classes using de Melker et al. (2006. J Infect. 53(2):106-13) formula. RESULTS: The mean number of samples in each 10-year age class was 466 (SD 20.5), except for 90-99 year olds which contained 65 samples. More than half of all subjects (58.1%) had anti-PT IgG <5.0IU/mL, 2.7% had 62.5 to <125IU/mL and 0.6% ≥125IU/mL; no differences occurred between 10-year age classes. Estimated incidence of pertussis infection was 5.8% (95% CI 4.8-7.0) in 2012, with peaks observed in 20-29 year olds (11.0%; 95% CI 7.4-15.6) and 90-99 year olds (10.8%; 95% CI 3.0-26.2). Estimated pertussis incidence rate was 915 times higher than reported. Of 80 subjects with anti-PT IgG ≥62.5IU/mL, 25 (31.3%) had complained of coughing to their GP during the previous six months. CONCLUSION: The frequency of pertussis infection was similar for all ages, suggesting similar Bordetella pertussis activity in adults and children. The wide gap between reported and estimated incidence indicates poor recognition of pertussis, likely owing to it being an asymptomatic or mild disease.

Seroprevalence of IgG antibodies to pertussis toxin in children and adolescents in Estonia.

BACKGROUND AND AIMS: Despite high immunisation coverage and frequent booster doses, the national notification rates of pertussis in Estonia have been increasing. The peak of 97/100,000 was reached in 2010 which is the highest incidence rate since 1962 (210/100,000). We aimed to measure the prevalence of pertussis toxin (PT) IgG type antibodies in subjects of <18 years and to estimate the pertussis infection activity in a recently non-immunised cohort. METHODS: In a cross-sectional serosurvey, all consecutive leftover sera were collected in the Tartu University Hospital during April-August 2012. Anti-PT IgG concentration was measured by commercial ELISA and analysed in yearly cohorts. The antibody concentrations ≥62.5 IU/mL was considered suggestive to pertussis in the last year among 9- to 14-year-olds. RESULTS: The GMC of the anti-PT-IgG was 7.4 IU/mL (95% CI 6.9-8.0). In the total of 1053 serum samples, the highest proportion of sera with high antibody titres ≥125 IU/mL and ≥62.5 IU/mL were at the ages when pertussis vaccine boosters were given: 7 years 10.9% (95% CI 4.1-22.3) and 2 years 36.9% (95% CI 25.3-49.8), respectively. Approximately half of all sera had undetectable anti-PT IgG levels. The estimated incidence of Bordetella pertussis infection among 9- to 14-year-olds in the year before serum sampling was 6.3% (95% CI 3.3-10.8), which is at least 60 times higher than the officially reported incidence of pertussis disease in respective years. CONCLUSIONS: The serologic method is not suitable for diagnosing pertussis in instances when the last pertussis immunisation was less than one year ago. The relatively high proportion of subjects with undetectable anti-PT IgG levels and the relatively low rate of officially reported pertussis cases suggest that low antibody levels do not necessarily indicate the absence of protection. The estimated incidence rate of pertussis is much higher than officially reported figures, which suggests that asymptomatic/mild B. pertussis infection remains unrecognised and unreported.