[Infection fatality rate (IFR) during the course of COVID-19 pandemic in Upper Silesia Metropolitan Area (Poland) in 2020]. / Wskaznik smiertelnosci infekcji (IFR) w przebiegu pandemii COVID-19 w Aglomeracji Górnoslaskiej w 2020 r.

BACKGROUND: During the course of COVID-19 pandemic, a wide range of scientific projects was implemented worldwide, including studies focusing on infection fatality rate (IFR). The value of IFR depends on the number of COVID-19 deaths in a population in a given period and the number of infected people in this population, usually provided by seropepidemiological studies (anti-SARS-CoV-2 IgG in the case of COVID-19). The objective of our study was to estimate IFR in the course of COVID-19 pandemic in 2020, in the general population of Upper Silesia Metropolitan Area (USMA). MATERIAL AND METHODS: The seroepidemiological study was conducted in October-November 2020. Among randomly selected inhabitants of Katowice, Gliwice, and Sosnowiec (N = 1167), the presence of SARS-CoV-2 virus infection was assessed based on a positive IgG test result performed with the ELISA method. Data on deaths due to COVID-19 were obtained from the Registry Offices of each city. The infection fatality rate was calculated using the formula IFR (%) = [number of deaths/number of infected] × 100. RESULTS: Results of our study showed the prevalence of infection at 11.4% (95% CI: 9.5-13.2). In three examined towns, in the period January-November 2020, there was a total of 516 COVID-19 deaths. The resulting crude IFR was 0.65% (95% CI: 0.56-0.78). The IgG test had 88% sensitivity and 99% specificity and these figures were used to adjust IFR. The adjusted IFR value was similar to the crude value: IFR = 0.62% (95% CI: 0.53-0.74). CONCLUSIONS: The value of IFR estimated for the USMA population was similar to average values obtained in other countries and can be used as the background for monitoring the course and impact of COVID-19 pandemic in the Upper Silesian Industrial Area. Med Pr. 2021;72(6):671-6.

Association between Influenza Vaccination and Positive SARS-CoV-2 IgG and IgM Tests in the General Population of Katowice Region, Poland.

The explanation of the potential interaction between the influenza vaccine and SARS-CoV-2 infection is urgently needed in the public health. The objective of the study is to compare the occurrence of positive SARS-CoV-2 IgG and IgM tests in subjects with and without recent (last year) seasonal influenza vaccinations. In a cross-sectional study located in three large towns of Silesian Voivodeship (Poland), we studied 5479 subjects in which 1253 (22.9%) had a positive anti-SARS-CoV-2 IgG test and 400 (7.3%) had a positive anti-SARS-CoV-2 IgM test. Seasonal influenza vaccination remains an independent factor protecting against positive IgG tests (OR = 0.68; 0.55-0.83). The effect is not apparent with IgM antibodies. The obtained results confirmed that the serological status of SARS-CoV-2 infection depends on vaccination against seasonal influenza.

SARS-CoV-2 Antibody Seroprevalence in Wuhan, China, from 23 April to 24 May 2020.

The outbreak of coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, in December 2019. To investigate the prevalence of COVID-19 in Wuhan, we conducted serologic tests on 35,326 individuals from four different communities to estimate cumulative incidence of infection. Our results showed that 1,332 individuals (3.77%) showed positive COVID-19 antibody (either IgM or IgG). Males had a lower positivity rate than females (3.02% versus 4.52%). The antibody positivity rates showed a clear trend of increase according to patients' ages and varied among different communities. The results indicate that public health interventions may play important roles in the control of COVID-19.IMPORTANCE Coronavirus disease 2019 (COVID-19) was first detected in December 2019 in Wuhan, China. Afterwards, a number of public health interventions were implemented, including lock-down, face mask ordinances, and social distancing. Studies that rely on viral RNA testing of symptomatic patients have shown that these multifaceted interventions contributed to the control of the COVID-19 outbreak in Wuhan and delayed the epidemic's progression. However, these estimates of confirmed cases may miss large numbers of asymptomatic patients and recovered symptomatic patients who were not tested. To investigate the prevalence of COVID-19 in Wuhan, we conducted serologic tests on 35,326 individuals to estimate the cumulative incidence of infection. The results suggest that public health interventions may play important roles in the control of COVID-19.

COVID-19-related risk of in-hospital death in Silesia, Poland.

INTRODUCTION: The situation regarding COVID­19 in Poland is rapidly evolving. Because of this, it is important to investigate COVID­19 mortality and its predictors in one of the most densely populated regions of the country, Silesia Province. OBJECTIVES: The goals of this study were to assess in­hospital mortality due to COVID­19 and the impact of sex, age, and coexisting diseases on the risk of death. PATIENTS AND METHODS: The data analysis was based on discharge reports of patients with COVID­19 hospitalized between March and June 2020 in all hospitals in the region. Age, sex, hospital discharge status, and the presence of coexisting diseases were abstracted from the charts. RESULTS: In a group of 2830 in­patients with COVID­19, 325 died during hospitalization. COVID­19 deaths were associated with male sex (odds ratio [OR], 1.52; 95% CI, 1.17-1.96), older age (OR, 6.11; 95% CI, 4.5-8.31), and the presence of 3 or more coexisting diseases (OR, 4.78; 95% CI, 3.52-6.49). The most prevalent comorbidities were chronic cardiovascular and respiratory diseases. CONCLUSIONS: The estimated in­hospital fatality rate for COVID­19 was 11.5%, which is lower than the average COVID­19 fatality rate in other European countries. The risk of in­hospital death was associated with sex, age, and the number of coexisting diseases, such as chronic cardiovascular and respiratory diseases.

Seroprevalence of Anti-SARS-CoV-2 Antibodies in a Random Sample of Inhabitants of the Katowice Region, Poland.

Lack of knowledge around seroprevalence levels of COVID-19 in Poland was the reason for the implementation of a seroepidemiological study in the Katowice Region (2,100,000 inhabitants). In October-November 2020, a questionnaire examination and measurement of anti-SARS-CoV-2 IgG and IgM antibodies were performed in a random sample of the general population (n = 1167). The objectives of the study were to estimate the prevalence of IgG and IgM antibodies and to assess their host-related correlates. The prevalence of IgG seropositivity was 11.4% (95% CI: 9.5-13.2%) and IgM seropositivity was 4.6% (95% CI: 3.5-5.8%). Diagnosis of COVID-19 was found in 4.8% of subjects. A positive IgG test was statistically significantly associated with age (inverse relationship), a person's contact with a COVID-19 patient, quarantine, and two symptoms in the past: fever and loss of smell/taste. Positive IgG tests were less prevalent in subjects who had diagnoses of arterial hypertension, diabetes, or rheumatologic disorders. IgM test positivity was associated with quarantine and loss of smell/taste only with no effect of chronic diseases found. In Poland, in the period October-November 2020, the prevalence of SARS-CoV-2 infection was larger than earlier estimates obtained in other European countries, probably reflecting the measurements obtained during the "second wave" of the epidemic.