Immune Response 5-7 Months after Vaccination against SARS-CoV-2 in Elderly Nursing Home Residents in the Czech Republic: Comparison of Three Vaccines.

BACKGROUND AND AIMS: Elderly nursing home residents are especially prone to a severe course of SARS-CoV-2 infection. In this study, we aimed to investigate the complex immune response after vaccination depending on the convalescence status and vaccine. METHODS: Sampling took place in September-October 2021. IgG antibodies against spike protein and nucleocapsid protein, the titer of virus neutralization antibodies against delta and (on a subset of patients) omicron, and cellular immunity (interferon-gamma release assay) were tested in nursing home residents vaccinated with Pfizer, Moderna (both 30-31 weeks after the completion of vaccination), or AstraZeneca (23 weeks) vaccines. The prevalence with 95% confidence intervals (CI) was evaluated in Stata version 17. RESULTS: 95.2% (95% CI: 92.5-97.1%) of the 375 participants had positive results of anti-S IgG, 92.8% (95% CI: 89.7-95.2%) were positive in virus neutralization assay against delta, and 89.0% (95% CI: 84.5-92.5%) in the interferon-gamma-releasing assay detecting cellular immunity. Results of the virus neutralization assay against omicron correlated with those against delta but the neutralization capacity was reduced by about half. As expected, the worst results were found for the AstraZeneca vaccine, although the vaccination-to-test period was the shortest for this vaccine. All immune parameters were significantly higher in convalescent residents than in naive residents after vaccination. No case of COVID-19 occurred during the vaccination-to-test period. CONCLUSIONS: A high immune response, especially among vaccinated convalescents (i.e., residents with hybrid immunity), was found in elderly nursing home residents 5-7 months after vaccination against SARS-CoV-2. In view of this, it appears that such residents are much better protected from COVID-19 than those who are only vaccinated and the matter of individual approach to the booster dose in such individuals should be further discussed.

Performance of Seven SARS-CoV-2 Self-Tests Based on Saliva, Anterior Nasal and Nasopharyngeal Swabs Corrected for Infectiousness in Real-Life Conditions: A Cross-Sectional Test Accuracy Study.

Many studies reported good performance of nasopharyngeal swab-based antigen tests for detecting SARS-CoV-2-positive individuals; however, studies independently evaluating the quality of antigen tests utilizing anterior nasal swabs or saliva swabs are still rare, although such tests are widely used for mass testing. In our study, sensitivities, specificities and predictive values of seven antigen tests for detection of SARS-CoV-2 (one using nasopharyngeal swabs, two using anterior nasal swabs and four using saliva) were evaluated. In a setting of a high-capacity testing center, nasopharyngeal swabs for quantitative PCR (qPCR) were taken and, at the same time, antigen testing was performed in accordance with manufacturers' instructions for the respective tests. In samples where qPCR and antigen tests yielded different results, virus culture was performed to evaluate the presence of the viable virus. Sensitivities and specificities of individual tests were calculated using both qPCR and qPCR corrected for viability as the reference. In addition, calculations were also performed for data categorized according to the cycle threshold and symptomatic status. The test using nasopharyngeal swabs yielded the best results (sensitivity of 80.6% relative to PCR and 91.2% when corrected for viability) while none of the remaining tests (anterior nasal swab or saliva-based tests) came even close to the WHO criteria for overall sensitivity. Hence, we advise caution when using antigen tests with alternative sampling methods without independent validation.

Covid-19 antigen testing: better than we know? A test accuracy study.

BACKGROUND: Antigen testing for SARS-CoV-2 is considered to be less sensitive than the standard reference method - real-time PCR (RT-PCR). It has been suggested that many patients with positive RT-PCR 'missed' by antigen testing might be non-infectious. METHODS: In a real-world high-throughput setting for asymptomatic or mildly symptomatic patients, 494 patients were tested using RT-PCR as well as a single lateral flow antigen test (Ecotest, AssureTech, China). Where the results differed, virus viability was evaluated by cell culture. The test parameters were calculated with RT-PCR and RT-PCR adjusted on viability as reference standards. RESULTS: The overall sensitivity of the used antigen test related to the RT-PCR only was 76.2%, specificity was 97.3%. However, 36 out of 39 patients 'missed' by the antigen test contained no viable virus. After adjusting on that, the sensitivity grew to 97.7% and, more importantly for disease control purposes, the negative predictive value reached 99.2%. CONCLUSIONS: We propose that viability testing should be always performed when evaluating a new antigen test. A well-chosen and validated antigen test provides excellent results in identifying patients who are shedding viable virus (although some caveats still remain) in the real-world high-throughput setting of asymptomatic or mildly symptomatic individuals.

Five Antigen Tests for SARS-CoV-2: Virus Viability Matters.

Antigen testing for SARS-CoV-2 (AGT) is generally considered inferior to RT-PCR testing in terms of sensitivity. However, little is known about the infectiousness of RT-PCR positive patients who pass undetected by AGT. In a screening setting for mildly symptomatic or asymptomatic patients with high COVID-19 prevalence (30-40%), 1141 patients were tested using one of five AGTs and RT-PCR. Where the results differed, virus viability in the samples was tested on cell culture (CV-1 cells). The test battery included AGTs by JOYSBIO, Assure Tech, SD Biosensor, VivaChek Biotech and NDFOS. Sensitivities of the ATGs compared to RT-PCR ranged from 42% to 76%. The best test yielded a 76% sensitivity, 97% specificity, 92% positive, and 89% negative predictive values, respectively. However, in the best performing ATG tests, almost 90% of samples with "false negative" AGT results contained no viable virus. Corrected on the virus viability, sensitivities grew to 81-97% and, with one exception, the tests yielded high specificities >96%. Performance characteristics of the best test after adjustment were 96% sensitivity, 97% specificity, 92% positive, and 99% negative predictive values (high prevalence population). We, therefore, believe that virus viability should be considered when assessing the AGT performance. Also, our results indicate that a well-performing antigen test could in a high-prevalence setting serve as an excellent tool for identifying patients shedding viable virus. We also propose that the high proportion of RT-PCR-positive samples containing no viable virus in the group of "false negatives" of the antigen test should be further investigated with the aim of possibly preventing needless isolation of such patients.

[Two case reports of chronic hepatitis C retreatment].

In a group of 211 patients with chronic hepatitis C treated with direct-acting antivirals, four experienced therapy failure. Two patients, one originally treated with dasabuvir/ombitasvir/paritaprevir/ritonavir and the other with glecaprevir/pibrentasvir, received a triple combination of sofosbuvir, velpatasvir and voxilaprevir for 12 weeks. Following the retreatment, both patients were permanently virus-free.

Serological survey of measles immunity in the Czech Republic, 2013.

OBJECTIVES: The aim of the serological survey of measles was to obtain information on the prevalence of antibodies against measles and to verify the effectiveness of vaccination in the Czech population in order to protect public health. METHODS: The serological survey was carried out in the Czech Republic in 2013. Antibodies against measles were tested in 3,111 serum samples of participants aged 1-64 years. Serum samples were tested for the presence of immunoglobulin G (IgG) antibodies by enzyme immunoassay (EIA). The vaccination status assessment was based on the medical documentation. Seroprevalence differences were evaluated by sex and age using the Pearson's χ2 test at 5% significance level. RESULTS: The overall seroprevalence reached 93.0% (2,893/3,111) (95% CI 92.0-93.9). No statistically significant difference was found between men and women (p=0.724). A lower seroprevalence was identified in the first age group (1-year old children) 62% (62/100), as the vaccination has not yet been completed in this age group. The second lowest seroprevalence 80.4% (160/199) was identified in the age group of 35-44 years. The highest seroprevalence 97.7% (387/396) (95% CI 95.7-99.0) was in the population with naturally-induced immunity (age above 45 years). In the individuals with two doses seroprevalence reached 94.1% (2,081/2,212) (95% CI 93.0-95.0). The level of IgG antibodies decreased in persons above 7 years of age. CONCLUSIONS: Based on the results of the serological survey carried out in 2013 in the Czech Republic, it has been decided to postpone the second MMR (measles, mumps and rubella) dose to the age of 5-6 years.

[Vertical hepatitis C transmission - authors' experiences].

BACKGROUND: Vertical hepatitis C virus (HCV) transmission and persistence of anti-HCV antibodies were retrospectively investigated since 1999 in a group of 244 children whose mothers had a history of hepatitis C. MATERIAL AND METHODS: Initial examinations performed in most children at 6 months of age included the determination of anti-HCV antibodies, HCV nucleic acid (HCV RNA), and anti-HIV antibodies, with all children being negative for HIV. Further examinations with investigation of anti-HCV and HCV RNA were performed at half-year intervals until the disappearance of anti-HCV antibodies. Vertical HCV transmission was defined by HCV RNA positivity in at least 2 venous blood samples or at least two positive anti-HCV results in a child over 3 years of age. RESULTS: Vertical HCV transmission was detected in 11 out of 244 children (4.5%). Only 2 children spontaneously cleared HCV; positive anti-HCV antibodies were last detected when they were 8 years old. Chronic hepatitis C developed in 9 children, four of whom were infected with genotype 1b, 3 children with genotype 3a, one with genotype 1a, and the last one with genotypes 1a and 4. Antiviral treatment including conventional or pegylated interferon, or ribavirin, was administered to 3 children, with sustained elimination of the virus in 2 children. Although the proportion of children with positive anti-HCV antibodies declined gradually, anti-HCV positivity was reported in 6 uninfected children at 18 months of age but in none of them at the age of 2 years. CONCLUSIONS: Vertical transmission of HCV was found in 11 out of 244 children; chronic hepatitis C was detected in 9 children; uninfected children cleared anti-HCV antibodies by 2 years of age.

[Investigation of autoimmunity markers during interferon alpha therapy of chronic hepatitis B and C - twenty years of experience]. / Sledování autoimunitnich fenoménu pri lécbe chronické hepatitidy B a C interferonem alfa - dvacetileté zkusenosti.

OBJECTIVE: To determine the prevalence of autoimmune parameters in patients with chronic hepatitis B and C (HBV, HCV) treated with conventional or pegylated interferon alpha (IFN) and monitor the development of autoimmune diseases in connection with this treatment. PATIENTS AND METHODS: In the years 1992-2014, autoimmune parameters were evaluated in 324 patients (271 with HCV, 53 with HBV) treated with IFN at the Department of Infectious Diseases in Ostrava. Prior to, during and after completion of IFN treatment, antinuclear antibodies (ANA), antimitochondrial antibodies (AMA), smooth muscle antibodies (SMA), anti-liver/kidney microsomal antibodies (anti-LKM-1), anti-double-stranded DNA antibodies (anti-ds-DNA), antibodies against granulocytes (ANCA), anti-deoxyribonucleoprotein antibodies (anti-DNP), anti-nucleosomes antibodies, rheumatoid factor (RF) and circulating immune complexes (CIC) were determined and clinical manifestations of autoimmune diseases were evaluated. RESULTS: At least one abnormal parameter was present in 267 of 324 patients: ANA in 140, AMA in 13, SMA in 100, RF in 118, ANCA in 11, anti-ds-DNA in 2 and anti-LKM-1 in 1 patient. Increases in CIC were observed in 150 of 227 patients, anti-DNP positivity in 39 of 239 and anti-nucleosomes were positive in none of 43 patients. At least one abnormal parameter was detected in 85 % of patients with HCV and in 89 % of patients with hepatitis B, in 81 % of patients under 40 years of age and in 84 % of older indivi-duals, 90 % of patients with cirrhosis and 80 % without cirrhosis, in 74 % of patients with treatment shorter than 30 weeks and in 87 % of patients with treatment lasting over 50 weeks. Autoimmune diseases - autoimmune hepatitis, autoimmune myositis, myopathy and diabetes - developed in 4 patients while only 3 individuals had ANA, SMA or anti-DNP positivity. CONCLUSIONS: Positivity of ANA and SMA or increased RF and CIC are often found in patients with HBV and HCV treated with IFN, but their presence does not correlate with the development of autoimmune diseases.

[Thyroid dysfunction during interferon alpha therapy for chronic hepatitis B and C - twenty years of experience].

OBJECTIVE: To determine the incidence of thyroid dysfunction in patients with chronic hepatitis B and C (HBV, HCV) who were treated with interferon (IFN) alpha. PATIENTS AND METHODS: In the years 1992-2013, parameters of the thyroid gland were evaluated in 304 patients (256 with HCV, 48 with HBV) who were treated with conventional or pegylated IFN at the Department of Infectious Diseases in Ostrava. Prior to, during and after completion of antiviral treatment, levels of thyroid stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3), including their free fractions fT4 and fT3, and anti-thyroid antibodies (anti-thyroglobulin, anti-microsomal fraction) were determined and clinical manifestations of thyroid dysfunction were evaluated. RESULTS: TSH changes were detected in 75 patients (25 %), of whom 68 had HCV and 7 HBV. Hypothyroidism was detected in 39 patients (34 with HCV), of whom 25 required substitute therapy which was subsequently terminated in 5 patients. Hyperthyroidism with transient suppressive therapy with carbimazole developed in 4 HCV patients. In 32 patients, TSH changes were assessed as subclinical hypothyroidism. Abnormal T3 values were found in 188 (62 %) and T4 in 49 (16 %) patients; these changes practically did not correlate with TSH changes. Autoantibodies were detected in 54 (18 %) patients of whom 30 were also found to have changes in TSH. CONCLUSIONS: In a group of 304 patients treated with IFN alpha for chronic hepatitis, thyroid disease with changes in TSH were observed in a quarter of patients; hypothyroidism clearly prevailed. Thyroid diseases developed in half of the patients with the presence of antithyroid antantibodies.

[Low response rate to a vaccination against hepatitis B in patients with end-stage liver disease]. / Malá úcinnost vakcinace proti virové hepatitide B u pacientu s pokrocilým jaterním onemocnením.

Hepatitis B vaccination was started in 41 patients with end-stage liver disease who were liver transplant candidates. Patients received three 20 microg or, starting from 1999, 40 microg doses of recombinant vaccine at 0, 2 and 4 weeks. Blood samples were obtained 4 weeks after vaccination or each revaccination; patients without protective hepatitis B surface antibodies (anti-HBs) were once or repeatedly revaccinated. Thirty-eight patients received at least 3 doses of vaccine. Protective anti-HBs level (≥ 10 IU/l) was detected in 17 of 34 patients (50 %) after the third up to eight dose. No case of chronic HBsAg carrier status was detected. Immunisation against hepatitis B in persons with liver cirrhosis is associated with a poor response and new vaccines should be considered for these patients.