Characterizing the transmission patterns of seasonal influenza in Italy: lessons from the last decade

BACKGROUND

Despite thousands of influenza cases annually recorded by surveillance systems around the globe, estimating the transmission patterns of seasonal influenza is challenging.

METHODS

We develop an age-structured mathematical model to influenza transmission to analyze ten consecutive seasons (from 2010 to 2011 to 2019-2020) of influenza epidemiological and virological data reported to the Italian surveillance system.

RESULTS

We estimate that 18.4-29.3% of influenza infections are detected by the surveillance system. Influenza infection attack rate varied between 12.7 and 30.5% and is generally larger for seasons characterized by the circulation of A/H3N2 and/or B types/subtypes. Individuals aged 14 years or less are the most affected age-segment of the population, with A viruses especially affecting children aged 0-4 years. For all influenza types/subtypes, the mean effective reproduction number is estimated to be generally in the range 1.09-1.33 (9 out of 10 seasons) and never exceeding 1.41. The age-specific susceptibility to infection appears to be a type/subtype-specific feature.

CONCLUSIONS

The results presented in this study provide insights on type/subtype-specific transmission patterns of seasonal influenza that could be instrumental to fine-tune immunization strategies and non-pharmaceutical interventions aimed at limiting seasonal influenza spread and burden.

The early phase of the COVID-19 epidemic in Lombardy, Italy

Background

In the night of February 20, 2020, the first epidemic of the novel coronavirus disease (COVID-19) outside Asia was uncovered by the identification of its first patient in Lombardy region, Italy. In the following weeks, Lombardy experienced a sudden increase in the number of ascertained infections and strict measures were imposed to contain the epidemic spread.

Methods

We analyzed official records of cases occurred in Lombardy to characterize the epidemiology of SARS-CoV-2 during the early phase of the outbreak. A line list of laboratory-confirmed cases was set up and later retrospectively consolidated, using standardized interviews to ascertained cases and their close contacts. We provide estimates of the serial interval, of the basic reproduction number, and of the temporal variation of the net reproduction number of SARS-CoV-2.

Results

Epidemiological investigations detected over 500 cases (median age: 69, IQR: 57–78) before the first COVID-19 diagnosed patient (February 20, 2020), and suggested that SARS-CoV-2 was already circulating in at least 222 out of 1506 (14.7%) municipalities with sustained transmission across all the Lombardy provinces. We estimated the mean serial interval to be 6.6 days (95% CrI, 0.7–19). Our estimates of the basic reproduction number range from 2.6 in Pavia (95% CI, 2.1–3.2) to 3.3 in Milan (95% CI, 2.9–3.8). A decreasing trend in the net reproduction number was observed following the detection of the first case.

Conclusions

At the time of first case notification, COVID-19 was already widespread in the entire Lombardy region. This may explain the large number of critical cases experienced by this region in a very short timeframe. The slight decrease of the reproduction number observed in the early days after February 20, 2020 might be due to increased population awareness and early interventions implemented before the regional lockdown imposed on March 8, 2020.

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Over 500 cases (median age: 69, IQR: 57–78) declaring symptom onset before the notification of the first case (20 February 2020) were retrospectively detected.

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SARS-CoV-2 was already circulating in at least 222 out of 1506 (14.7%) municipalities of Lombardy.

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The estimated mean serial interval was 6.6 days (95% CrI, 0.7–19).

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The basic reproduction number in the 12 provinces of Lombardy ranged from 2.6 (95% CI, 2.1–3.2) to 3.3 (95% CI, 2.9–3.8).

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A decreasing trend in the net reproduction number following the detection of the epidemic and the introduction of the first restrictive measures.

Potential short-term outcome of an uncontrolled COVID-19 epidemic in Lombardy, Italy, February to March 2020

Sustained coronavirus disease (COVID-19) transmission is ongoing in Italy, with 7,375 reported cases and 366 deaths by 8 March 2020. We provide a model-based evaluation of patient records from Lombardy, predicting the impact of an uncontrolled epidemic on the healthcare system. It has the potential to cause more than 250,039 (95% credible interval (CrI): 147,717-459,890) cases within 3 weeks, including 37,194 (95% CrI: 22,250-67,632) patients requiring intensive care. Aggressive containment strategies are required.

Drinking water quality: results from the data analysis in Lombardy region

Background

Ensuring access to safe and quality drinking water is an essential aspect of public health, as well as a fundamental human right as an extension of the right to life affirmed by the Universal Declaration of Human Rights. Previously in Lombardy, the reporting of water sampling control activities was prepared only by the local health authorities (LHAs). Recently, however, the activation of a data centralization information system allows the monitoring of the whole regional territory and the elaboration of a periodic report.

Methods

The data relating to the analytical checks on drinking water in the Lombardy Region were extracted from the regional database for 2014, 2015 and 2016 and grouped by ’Chemical’, ’Microbiological’ and ’Indicators’ parameters.

The analysis focused on the number and analytical compliance of all the samples performed. All the results considered both the overall regional data and each LHA.

Results

From a quantitative point of view, the activity of entering the sampling data seems to progressively improve, remaining rather heterogeneous among the various LHAs.

From a qualitative point of view drinking water in Lombardy is to be considered good overall: both the chemical and microbiological non-compliant samples in Lombardy are lower than 10% for the years 2014 and 2015 and lower than 5% in 2016 thus indicating an apparently improving trend.

Conclusions

For a better evaluation of the numerical appropriateness of the controls carried out, an update of the registry system of the supply areas and a more uniform LHA programming is necessary.

For a better assessment of the quality of water destined for human consumption oriented to the conformity of parameters, it is necessary to adopt an analytical judgment system on individual parameters instead of on the entire sample. A further improvement will be the inclusion in the database of the data of the aqueduct managers included in the Water Safety Plans (WSPs).

Key messages

Water quality assessment and its control activity reporting is an essential aspect in public health prevention. It is essential to strive for continuous improvement in the data collection method to better monitor potential risks and to evaluate the best future safe water supply strategies.