Probability of exposure to the wild measles virus in adult population - Estimation from seroepidemiology and historical data

Vaccination against measles is one of the most effective public health interventions which has saved millions of lives and interrupted circulation of the natural virus in the population. However, it is widely accepted that the immunity after vaccination can wane, especially in those who have had no contact with the virus. This study aimed to classify the particular birth cohorts of adults with regard to their exposure to the wild measles virus in the population with a long history of mandatory vaccination. We introduced two methods. In the first, we estimated the probability of exposure to the wild virus through an analysis of antibody levels from the Immunologic Survey performed in the Slovak Republic in 2018, while the second was based on historical epidemiological data. Both methods resulted in similar estimations. Cohorts born in Slovakia before 1964 can be considered to be cohorts in which most people were exposed to the wild measles virus. Cohorts born after 1977 can be designated as cohorts that most likely did not come into the contact with the wild virus. Cohorts born between 1965 and 1976 are composed of a mixture, with a decreasing proportion of people exposed to the wild virus with increasing year of birth. The proposed methods can help identify potential immunity gaps in the adult population. They can be applied in other countries with high measles vaccination coverage to estimate the probability of exposure to the wild measles virus in particular birth cohorts.

Quantification of Waning Immunity After Measles Vaccination-Evidence From a Seroprevalence Study

We aimed to quantify rates of waning immunity after measles vaccination from seroprevalence data collected in a study of a population with high vaccination coverage and a fixed vaccination schedule. Data were collected during a national survey (the Immunological Survey) carried out in the Slovak Republic in 2018. The average rate of waning immunity against measles after the first dose of measles, mumps, and rubella (MMR) vaccine (ages 1.5-10 years) was 9.7% per year from the geometric mean titer value of 2,634 mUI/mL. The average waning rate after the second dose of MMR vaccine (ages 10-33 years) was significantly lower: 4.8% per year from the lower geometric mean titer of 1,331 mUI/mL. This decline in antibody levels suggests that vaccine-induced protection may be compromised and results in an increase in the proportion of seronegative/borderline individuals. These outcomes may provide a valuable source for critical assessment of direct and indirect effects of MMR vaccination.

The first laboratory confirmed invasive meningococcal disease of serogroup C with abdominal clinical presentation in Slovakia, 2019

Acute abdominal clinical presentations as initial manifestation of meningococcal infection are uncommon and frequently provoked by hyperinvasive isolates of meningococci. 10% of patients infected by the meningococcal strain, that is on the rise in Europe, suffer from abdominal pain. We hereby report the first laboratory confirmed fatal case of an otherwise healthy adult male presented with acute abdominal pain during first 24-48 hours, masking Neisseria meningitidis (N. meningitidis) infection. In the National Reference Center for meningococci, in the blood of a man post-mortem, we identified N. meningitidis serogroup C using real time polymerase chain reaction (PCR). Subsequently, massivelly-parallel sequencing (MPS) was performed on isolated total DNA for pathogen confirmation and further investigation.

Determinants of Fatal Outcome in Patients Admitted to Intensive Care Units With Influenza, European Union 2009-2017

Background

Morbidity, severity, and mortality associated with annual influenza epidemics are of public health concern. We analyzed surveillance data on hospitalized laboratory-confirmed influenza cases admitted to intensive care units to identify common determinants for fatal outcome and inform and target public health prevention strategies, including risk communication.

Methods

We performed a descriptive analysis and used Poisson regression models with robust variance to estimate the association of age, sex, virus (sub)type, and underlying medical condition with fatal outcome using European Union data from 2009 to 2017.

Results

Of 13 368 cases included in the basic dataset, 2806 (21%) were fatal. Age ≥40 years and infection with influenza A virus were associated with fatal outcome. Of 5886 cases with known underlying medical conditions and virus A subtype included in a more detailed analysis, 1349 (23%) were fatal. Influenza virus A(H1N1)pdm09 or A(H3N2) infection, age ≥60 years, cancer, human immunodeficiency virus infection and/or other immune deficiency, and heart, kidney, and liver disease were associated with fatal outcome; the risk of death was lower for patients with chronic lung disease and for pregnant women.

Conclusions

This study re-emphasises the importance of preventing influenza in the elderly and tailoring strategies to risk groups with underlying medical conditions.

Risk factors for severe outcome of cases with pandemic influenza A(H1N1)pdm09

OBJECTIVES

The aim of this study is to describe demographic, clinical and epidemiological characteristics of cases with laboratory-confirmed pandemic influenza virus A(H1N1)pdm09 reported in Slovakia from May 28, 2009 to December 30, 2009 and analyse the association between risk factors and severe outcome of these cases.

BACKGROUND

In the spring of 2009, an outbreak of a pandemic influenza virus A(H1N1)pdm09, emerged in Mexico and spread globally. Until December 2009, 1,014 cases were notified in Slovakia.

METHODS

The data were collected within national influenza surveillance system. Odds ratios (95% CI) were calculated. Associations were found to be significantly associated with the worse outcome (p < 0.05) in the univariate analysis and were adjusted for possible effects of age and sex by using a logistic regression model.

RESULTS

Out of the total number of 1,014 cases, 131 (12.9 %) cases were hospitalized, and 43 (4.2 %) of those were admitted to intensive care units. During the reporting period, 38 deaths were reported, representing a case fatality rate of 3.75 %. The median age of severe cases (35 years, IQR = 29 y) was significantly higher than the median age of mild cases (24 years, IQR = 19 y; p < 0.001). By using a logistic regression, we found out that chronic obstructive pulmonary disease (COPD) (aOR = 9.2; 95%CI: 1.42-59.98), cardiovascular diseases (aOR = 14.97; 95%CI: 5.49-40.79), malignity (aOR = 7.6; 95%CI: 1.95-29.37) and gravidity (aOR = 55.21; 95% CI: 14.40-211.58) were significantly associated with severe outcomes of the cases.

CONCLUSION

The fact, that 35% of severely ill patients did not report any risk factor suggests the importance of vaccination as a prevention of influenza (Tab. 2, Fig. 1, Ref. 18). Text in PDF www.elis.sk.

Evaluation of clinical specimens for influenza A virus positivity using various diagnostic methods

The diagnostic method for Influenza A virus, utilizing the SERION ELISA Antigen kit (SERION EIA), if results were evaluated according to the manufacturer's instructions, has repeatedly failed to detect a great number of clinical samples positive by virus isolation and RT-PCR. Therefore we compared the SERION EIA with the one-step 44/107L-Px immunocapture enzyme immunoassay (44/107L-Px EIA), developed in our laboratory (Tkácová and Varecková, J. Virol. Methods 60, 65-71, 1996). Seventy-three clinical specimens, of which 65 were positive by virus isolation (used as reference method), were tested by both EIAs. By the SERION EIA, out of the 65 reference-positive samples only 8 (12%) were positive, 5 (8%) were ambiguous, and 52 (80%) were negative, which corresponded to the sensitivity of 12%. On the contrary, the sensitivity of the 44/107L-Px EIA was 74%. However, the calculation of cut-off values for the evaluation of positivity of clinical specimens in these two assays were not the same. If the evaluation procedure used for the 44/107L-Px EIA was applied to the SERION EIA, the sensitivity and the specificity of both EIAs became comparable, namely 71% and 100% for the SERION EIA and 74% and 100% for the 44/107L-Px EIA, respectively. From these results it follows that not the detection ability of the SERION EIA, but the evaluation procedure recommended by its manufacturer led to a loss of large number of positive specimens.