COVID-19 reinfections.

Reports of SARS-CoV-2 reinfections are on the rise. This study focused on reinfections in patients with confirmed COVID-19 in the Czech Republic. Between 1 March 2020 and 9 November 2020, 362 084 cases with the onset of symptoms before 31 October 2020 were reported. Overall, 28 cases of symptomatic SARS-CoV-2 reinfections were identified, 11 in males and 17 in females, age range 25-80 years, median age 46 years. The interval between the first and second episodes of the disease ranged from 101 to 231 days, and the median interval was 201.5 days. During both symptomatic episodes, all patients have been tested by RT-PCR. Altogether 26 patients (92.9%) have been tested negative after recovery from the first episode of COVID-19. Symptomatic reinfections occurred in nearly 0.2% of all patients at risk. Most patients with reinfection had mild symptoms in both episodes, and only three episodes were moderate to severe. Thus, reinfections may have been underdiagnosed. In summary, COVID-19 reinfections are possible and not exceptional.

Molecular and antigenic characterization of the H3 hemagglutinin of H3N2 influenza A virus strains collected in the Czech Republic during the 2014/2015 epidemic season.

The 2014/2015 influenza epidemic season was characterized by the predominance of the H3N2 subtype. The presented study investigated the genetic and antigenic heterogeneity of the H3N2 strains collected in the Czech Republic from November 2014 to March 2015. Phylogenetic analysis of the representative H3 hemagglutinin sequences was performed and the glycosylation status and crucial antigenic mutations were compared relative to the 2014 and 2015 vaccine strains (A/Texas/50/2012 and A/Switzerland/9715293/2013) and visualized in the H3 crystal structure. The molecular data were further supplemented by hemagglutination-inhibition test (HIT) results on fifteen H3N2 2014/2015 strains by using the A/Texas/50/2012 (H3N2) and A/Switzerland/9715293/13 (H3N2) antisera. Our data on the Czech H3N2 viruses from the 2014/2015 epidemic season could supplement the reports of official authorities with data from a particular geographi-cal area.

[Differential diagnosis of the viral etiology of suspected mumps in a population with high vaccine coverage]. / Diferenciální diagnostika virové etiologie suspektních príusnic ve vysoce proockované populaci.

AIM: In this study, buccal swabs from patients with the clinical picture of parotitis epidemica in whom mumps virus (MV) infection was not confirmed by direct detection or serologically were tested. The aim was to detect by molecular methods nucleic acids (NAs) of other respiratory viruses possibly involved in salivary gland swelling. At the same time, paired sera, if available, were tested. MATERIAL AND METHODS: The study group consisted of 72 buccal swabs from patients of the Clinic of infectious, tropical, and parasitic diseases, Na Bulovce Hospital. Paired sera were available from ten patients. Samples were collected in 2013 to 2015. Buccal swabs were tested by PCR for the presence of NAs of adenoviruses (AdV), bocaviruses (hBoV), parainfluenza viruses of types 1-4 (HPIV), human metapneumovirus (hMPV), coronaviruses (HCoV: NL63, OC43, HKU1, and 229E), respiratory syncytial virus (RSV), influenza A virus, influenza B virus, and Epstein-Barr virus (EBV). Paired sera were screened by the complement fixation test (AdV and influenza A and B viruses), hemagglutination inhibition test (HPIV types 2 and 3), ELISA (AdV, EBV), and immunofluorescence (EBV). RESULTS: NAs from viruses other than the mumps virus were detected in 27 of 72 patients with clinical symptoms of parotitis epidemica, and serological tests revealed etiological links with parainfluenza viruses in three more cases. Overall, 30 (41.7%) of 72 patients with suspected mumps tested positive for one or more viruses from the study panel. The most commonly detected viruses were AdV 11/72 (15.3%), EBV 9/72 (12.5%), and HPIV 3/72 (4.2%), but influenza A virus (H3N2) 1/72 (1.4%) was also found. Some patients tested positive for more than one virus: 2/72 (3%) for AdV plus hBoV and 1/72 (1.4%) for HPIV plus HCoV. In addition, examination of paired sera revealed HPIV positivity in three more patients. PCR and serology detected etiological link with HPIV in six (8.3%) of 72 patients tested. CONCLUSION: In our study group, nearly 42% of patients with the clinical picture of parotitis epidemica in whom mumps virus (MV) infection was not confirmed by direct detection or serologically tested positive for viruses other than the mumps virus. Thorough laboratory diagnosis of suspected mumps in vaccinated persons is important not only for the treatment of patients and adoption of isolation and other measures, but also for a better understanding of the epidemiology of the disease and outcomes of the immunisation programmes.

[Enterovirus sequencing as a new approach to the laboratory diagnosis for clinical and epidemiological purposes]. / Sekvenace enteroviru jako nový prístup k laboratorní diagnostice pro klinické i epidemiologické úcely.

OBJECTIVE: Introducing enterovirus sequencing as an advanced approach to classify the viruses isolated according to the novel nomenclature and to characterize isolates in detail. MATERIAL AND METHODS: Seventy-five specimens collected from 64 patients in two hospitals, Liberec Regional Hospital, and Plzen University Hospital, were analyzed. The study patients' age ranged from four to 54 years, with a median of 15 years in males and 16 years in females. In most patients, the reasons for admission were intense headache, fever, vomiting, tiredness, meningeal symptoms, intestinal symptoms (in two patients), and skin symptoms (in one patient). The specimens collected were rectal and throat swabs, cerebrospinal fluid (CSF) and stool specimens. Molecular detection and typing were performed using the RT-PCR method. A segment of the 5´non-coding RNA was selected for typing. Specimens were amplified using single-step PCR with external primers and with the same primers extended to include M13 sequences (Generi-Biotech). The LASERGENE software (DIASTAR) was used in sequence editing, alignment, and quality check. The sequences obtained were checked against the central GenBank sequence database using the BLAST algorithm. RESULTS: The identification of the study isolates resulted in 61 ECHO viruses 30, three coxsackie viruses B1, one coxsackie virus B3, one coxsackie virus A9, one enterovirus 86, one enterovirus 71, Two ECHO viruses 13/coxsackie virus B5, one ECHO virus 7/30/coxsackie virus B4, one coxsackie virus B4/enterovirus B, one enterovirus 87/ECHO virus 30/enterovirus B, and one ECHO virus 3. All viruses isolated, except enterovirus 71 classified into group A, were of group B. CONCLUSION: The enteroviruses were identified unambigously, although the sequencing only targeted a short, conserved segment that showed considerable variability. The sequencing was an effective alternative to enterovirus identification by the neutralisation test and allowed for detailed characterization of the isolates. The predominance of ECHO 30 as the cause of aseptic meningitis is in accordance with the literature data.

[Clinical and epidemiological characteristics of patients hospitalized with severe influenza in the season 2012-2013]. / Klinické a epidemiologické charakteristiky pacientu hospitalizovaných pro tezký prubeh chripky v sezone 2012-2013.

AIM OF THE STUDY: To characterize the clinical and epidemiological features of patients hospitalized with moderate to severe influenza infection at the infec-tious diseases department of a tertiary care hospital in the epidemic season 2012-2013. MATERIAL AND METHODS: A prospective observational study of patients hospitalized with influenza infection in the season 2012-2013 was carried out at the Infectious Diseases Department, Na Bulovce Hospital in Prague. Influenza infection was diagnosed by real-time quantitative polymerase chain reaction (RT-qPCR) in nasopharyngeal swab or tracheal aspirate specimens. Demographic, clinical, and laboratory data were recorded along with the disease course and outcome. RESULTS: One hundred and ninety-nine patients, 85 females and 114 males (age median 47, range 1-87 years), were hospitalized with confirmed influenza in the epidemic season 2012-2013. Only seven of them got the influenza vaccine. Altogether 136 patients were diagnosed with influenza type A (91 with H1N1pdm, 33 with H3N2, and 12 with an unknown subtype), 66 patients with type B, and three patients with both types A and B. One hundred and eight patients (54%) had an underlying chronic disease, most often cardiovascular or pulmonary. The main symptoms of influenza were fever, cough, headache, myalgia, and arthralgia. Pneumonia was the most common complication: twenty-one patients suffered from primary viral pneumonia and 35 from bacterial pneumonia. Twenty-three patients (12%) needed intensive care. Six patients died and the leading cause of death was heart failure. CONCLUSION: During the epidemic influenza season 2012-2013, more patients were hospitalized than in the pandemic season 2009-2010. Also the proportions of complicated cases and case fatality ratios were fully comparable in both seasons. The fact that most patients were not vaccinated clearly supports the recommendation to vaccinate every year both the individuals at high risk of complications due to comorbidities and the healthy population.

[Phylogenetic and molecular analysis of A/H1N1pdm influenza viruses isolated in the epidemic season 2012/2013 from hospitalised patients with -symptoms of influenza-like illness]. / Fylogenetická a molekulární analýza viru chripky A/H1N1pdm izolovaných v epidemické sezone 2012/2013 od pacientu hospitalizovaných s príznaky ILI.

AIM: To perform phylogenetic and molecular analysis of A/H1N1pdm influenza viruses isolated in the epidemic season 2012/2013 from hospitalised patients with symptoms of influenza-like illness (ILI). MATERIAL AND METHODS: The study set included 34 strains of the A/H1N1pdm influenza virus isolated in the Czech Republic in the epidemic season 2012/2013. The strains were analysed by partial or whole-genome sequencing. The genome segments were compared at the nucleotide and amino acid levels, absolute and percentage sequence identity were determined, and phylogenetic relations were identified. The last steps were the comparison of the H1 molecule with that of the most recent vaccine strain and identification of the genotypic structure and molecular markers linked to the pathogenicity and antiviral resistance. RESULTS: Phylogenetic analysis of the H1 molecule suggested that all 34 A/H1N1pdm isolates from the 2012/2013 season in the Czech Republic should be assigned to H1 group 6 divided into sublineages 6A and 6B. The comparison of the known antigenic regions of the H1 molecule with those in the most recent vaccine strain revealed two stable changes in antigenic regions Sb and Ca1. Furthermore, sporadic mutations were identified in antigenic regions Ca2, Cb, and Sb. Genotyping revealed co-circulation of two related but clearly distiguishable genotypes of A/H1N1pdm. All isolates showed sensitivity to oseltamivir. One strain consisted of two N1 sub-populations, one oseltamivir sensitive and the other oseltamivir resistant, in nearly equimolar proportions. CONCLUSION: All A/H1N1pdm isolates from the epidemic season 2012/2013 in the Czech Republic formed a phenotypically uniform group. At the nucleotide level, the divergence was relatively more pronounced and H1 sublineages and discrete genotypes were possible to identify. H1 molecules were highly identical to those of the vaccine strain A/California/7/2009 (H1N1) which showed that the current vaccine was protective enough. All strains were sensitive to oseltamivir; however, the selection of oseltamivir resistant N1 subpopulations was observed.

Early and unexpectedly severe start of influenza epidemic in the Czech Republic during influenza season 2012-13.

A sudden increase in severe influenza has been registered in the Czech Republic since the end of 2012, with 264 cases requiring intensive care, including 51 deaths. Most patients had at least one risk factor. Severe influenza in patients with obesity, smoking and/or haematological disorders including haematological cancers was more frequent than in the pre-pandemic period. The seasonal influenza vaccination status of the cases indicates indirect efficiency of the current vaccine in preventing severe influenza.