Waning protection of influenza vaccine against mild laboratory confirmed influenza A(H3N2) and B in Spain, season 2014-15.

INTRODUCTION: The 2014/15 influenza season in Spain was dominated by the circulation of drifted A(H3N2) and co-circulation of B viruses. We present the final estimates of influenza vaccine effectiveness (IVE) against confirmed influenza A(H3N2) and B its evolution along the season and with time since vaccination. METHODS: We used data collected on influenza like illness patients (ILI), systematically swabbed for the presence of influenza viruses within the Spanish Influenza Sentinel Surveillance System (SISS) and a restricted observational study (cycEVA). We used a test negative case-control design to compare influenza confirmed cases with negative controls. We estimated the IVE through a logistic regression model adjusting for potential confounders. The evolution of IVE was studied in early and late stages of the epidemic, and in different time intervals between receiving influenza vaccination and the onset of symptoms. RESULTS: At the end of the season we have found low and moderate IVE point estimates against influenza A(H3N2) and B, respectively, in all ages and target groups for vaccination. An IVE decreased from an early value of 37% to a late of -76% against influenza A(H3N2), and similarly, 84% vs -4% against Influenza B. When the onset of symptoms occurred more than three months after vaccination, the decrease of IVE was slower and milder against influenza B than against influenza A(H3N2). No significant change in the percentage of circulating drifted influenza A(H3N2) strains belonging to the 3c.2a and 3c.3a clades could be identified through the season. CONCLUSIONS: In a season dominated by drifted A(H3N2) circulating virus, the vaccine offered little or no protection against A(H3N2) infection but had a moderate protective effect against influenza B. Efforts should be put in developing influenza vaccines that maintain their protective capabilities throughout the season and could stimulate a potentially broad immune response against diverse influenza strains.

[Monitoring respiratory syncytial virus through the Spanish influenza surveillance system, 2006-2014]. / Vigilancia del virus respiratorio sincitial en el marco del Sistema de Vigilancia de la Gripe en España, 2006-2014.

INTRODUCTION: The aim of the study is to analyze the information on respiratory syncytial virus (RSV) obtained through the Spanish Influenza Surveillance System (SISS) and to study its usefulness as supplementary information for the characterization of influenza epidemics. METHODS: The temporal patterns of both RSV and influenza viruses were analyzed by patterns comparing the weekly viral detection rates from 2006 to 2014. RESULTS: In general, the RSV circulation was characterized by showing a peak between 52-1 weeks, and circulated from 2 to 8 weeks before/prior to influenza viruses. CONCLUSION: RSV information obtained from the SISS is useful for the characterization of influenza epidemics in Spain.

Higher vaccine effectiveness in seasons with predominant circulation of seasonal influenza A(H1N1) than in A(H3N2) seasons: test-negative case-control studies using surveillance data, Spain, 2003-2011.

BACKGROUND: We used data provided by the Spanish influenza surveillance system to measure seasonal influenza vaccine effectiveness (VE) against medically attended cases, laboratory confirmed with the predominately circulating influenza virus over eight seasons (2003-2011). METHODS: Using the test-negative case-control design, we compared the vaccination status of swabbed influenza-like illnesses (ILI) patients who were laboratory confirmed with predominantly circulating influenza strain in the season (cases) to that of ILI patients testing negative for any influenza (controls). Data on age, sex, vaccination status and laboratory results were available for all seasons. We used logistic regression to calculate adjusted influenza VE for age, week of swabbing, Spanish region and season. We calculated the influenza VE by each season and pooling the seasons with the same predominant type/subtype. RESULTS: Overall influenza VE against infection with A(H3N2) subtype (four seasons) was 31 (95% confidence interval (CI):10; 48). For seasonal influenza A(H1N1) (two seasons), the effectiveness was 86% (95% CI: 65; 94). Against B infection (three seasons), influenza VE was 47% (95% CI: 27; 62). CONCLUSIONS: The Spanish influenza surveillance system allowed estimating influenza VE in the studied seasons for the predominant strain. Strengthening the influenza surveillance will result in more precise VE estimates for decision making.

Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011-2012 season in Spain, among population targeted for vaccination.

BACKGROUND: In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza-like illness (ILI) among the target groups for vaccination in Spain in the 2011-2012 season. We also studied influenza VE in the early (weeks 52/2011-7/2012) and late (weeks 8-14/2012) phases of the epidemic and according to time since vaccination. METHODS: Medically attended patients with ILI were systematically swabbed to collect information on exposure, laboratory outcome and confounding factors. Patients belonging to target groups for vaccination and who were swabbed <8 days after symptom onset were included. Cases tested positive for influenza and controls tested negative for any influenza virus. To examine the effect of a late season, analyses were performed according to the phase of the season and according to the time between vaccination and symptoms onset. RESULTS: The overall adjusted influenza VE against A(H3N2) was 45% (95% CI, 0-69). The estimated influenza VE was 52% (95% CI, -3 to 78), 40% (95% CI, -40 to 74) and 22% (95% CI, -135 to 74) at 3.5 months, 3.5-4 months, and >4 months, respectively, since vaccination. A decrease in VE with time since vaccination was only observed in individuals aged ≥ 65 years. Regarding the phase of the season, decreasing point estimates were only observed in the early phase, whereas very low or null estimates were obtained in the late phase for the shortest time interval. CONCLUSIONS: The 2011-2012 influenza vaccine showed a low-to-moderate protective effect against medically attended, laboratory-confirmed influenza in the target groups for vaccination, in a late season and with a limited match between the vaccine and circulating strains. The suggested decrease in influenza VE with time since vaccination was mostly observed in the elderly population. The decreasing protective effect of the vaccine in the late part of the season could be related to waning vaccine protection because no viral changes were identified throughout the season.

Influenza-related mortality in Spain, 1999-2005.

OBJECTIVE: To estimate the excess deaths attributed to influenza in Spain, using age-specific generalized linear models (GLM) and the Serfling model for the period 1999-2005. METHOD: We reviewed mortality from influenza and pneumonia and all-cause deaths. We used an additive GLM procedure, including the numbers of weekly deaths as a response variable and the number of influenza virus and respiratory syncytial virus weekly isolates, the population and two variables to adjust for annual fluctuations as covariates. Using the Serfling model, we removed the trend and applied a temporal regression model, excluding data from December to April to account for the expected baseline mortality in the absence of influenza activity. RESULTS: Globally, the excess mortality attributable to influenza was 1.1 deaths per 100,000 for influenza and pneumonia and 11 all-cause deaths per 100,000 using the GLM model. The highest mortality rates were obtained with the Serfling model in adults older than 64 years, with an excess mortality attributable to influenza of 57 and 164 deaths per 100,000 for influenza and pneumonia and all-cause, respectively. CONCLUSIONS: The GLM model, which takes viral activity into account, yields systematically lower estimates of excess mortality than the Serfling model. The GLM model provides independent estimates associated with the activity of different viruses and even with other factors, which is a significant advantage when trying to understand the impact of viral respiratory infections on mortality in the Spanish population.

Using surveillance data to estimate pandemic vaccine effectiveness against laboratory confirmed influenza A(H1N1)2009 infection: two case-control studies, Spain, season 2009-2010.

BACKGROUND: Physicians of the Spanish Influenza Sentinel Surveillance System report and systematically swab patients attended to their practices for influenza-like illness (ILI). Within the surveillance system, some Spanish regions also participated in an observational study aiming at estimating influenza vaccine effectiveness (cycEVA study). During the season 2009-2010, we estimated pandemic influenza vaccine effectiveness using both the influenza surveillance data and the cycEVA study. METHODS: We conducted two case-control studies using the test-negative design, between weeks 48/2009 and 8/2010 of the pandemic season. The surveillance-based study included all swabbed patients in the sentinel surveillance system. The cycEVA study included swabbed patients from seven Spanish regions. Cases were laboratory-confirmed pandemic influenza A(H1N1)2009. Controls were ILI patients testing negative for any type of influenza. Variables collected in both studies included demographic data, vaccination status, laboratory results, chronic conditions, and pregnancy. Additionally, cycEVA questionnaire collected data on previous influenza vaccination, smoking, functional status, hospitalisations, visits to the general practitioners, and obesity. We used logistic regression to calculate adjusted odds ratios (OR), computing pandemic influenza vaccine effectiveness as (1-OR)*100. RESULTS: We included 331 cases and 995 controls in the surveillance-based study and 85 cases and 351 controls in the cycEVA study. We detected nine (2.7%) and two (2.4%) vaccine failures in the surveillance-based and cycEVA studies, respectively. Adjusting for variables collected in surveillance database and swabbing month, pandemic influenza vaccine effectiveness was 62% (95% confidence interval (CI): -5; 87). The cycEVA vaccine effectiveness was 64% (95%CI: -225; 96) when adjusting for common variables with the surveillance system and 75% (95%CI: -293; 98) adjusting for all variables collected. CONCLUSION: Point estimates of the pandemic influenza vaccine effectiveness suggested a protective effect of the pandemic vaccine against laboratory-confirmed influenza A(H1N1)2009 in the season 2009-2010. Both studies were limited by the low vaccine coverage and the late start of the vaccination campaign. Routine influenza surveillance provides reliable estimates and could be used for influenza vaccine effectiveness studies in future seasons taken into account the surveillance system limitations.

Influenza pandemic (H1N1) 2009 activity during summer 2009. Effectiveness of the 2008-9 trivalent vaccine against pandemic influenza in Spain.

INTRODUCTION: The Spanish influenza surveillance system (SISS) maintained its activity during the summer of 2009 to monitor the influenza pandemic. OBJECTIVES: To describe pandemic influenza activity from May to September 2009 and to estimate the effectiveness of the 2008-9 seasonal influenza vaccine against laboratory-confirmed pandemic (H1N1) 2009 influenza. METHODS: Data from the SISS were used to identify the trend of pandemic (H1N1) 2009 influenza outside the influenza season. For the effectiveness study, we compared the vaccination status of notified cases [influenza-like illnesses (ILI) laboratory confirmed as pandemic influenza] with that of the test-negative controls. RESULTS: The first laboratory-confirmed case of the pandemic virus was notified in the system in week 20/2009. The ILI rate increased gradually in the study period, exceeding basic activity in week 38. The proportion of pandemic (H1N1) 2009 influenza viruses detected by the system represented 14% in week 20/2009 and rapidly increased to 90% in week 34. The adjusted vaccine effectiveness of the 2008-9 seasonal vaccine against laboratory-confirmed pandemic influenza was 12% (-30; 41). CONCLUSIONS: The SISS became an essential tool for pandemic monitoring in Spain. The improved SISS will provide more accurate information on influenza activity in future seasonal or pandemic waves. Using surveillance data, we could not demonstrate the effectiveness of the seasonal 2008-9 vaccine against laboratory-confirmed pandemic influenza.

Differences in the reproductive pattern and low birthweight by maternal country of origin in Spain, 1996-2006.

BACKGROUND: Numerous studies have highlighted poorer reproductive and perinatal health outcomes among migrant mothers in developed countries. Due to the fact that no conclusive data is currently available at national level in Spain, this study aimed to explore potential differences by comparing the prevalence of low and multiple live births and the proportion of live births by maternal age and country of origin during 1996-2006. METHODS: A cross-sectional study was conducted using data from the National Statistics Institute. Low birthweight (LBW) was compared by mothers' country of origin using a logistic regression model. Odds ratios (ORs) and their respective 95% confidence intervals (CIs) are stratified by multiplicity and maternal age. RESULTS: LBW was associated with a combination of older maternal age and multiple pregnancies in the case of women who had been born in Europe (EU15). However, this association was not found in women who originated from outside the EU15, mostly from countries who have shown significant emigration to Spain during the last decade. LBW was present among all age groups, in both singleton and multiple births, and in particular Romanian mothers showed the highest OR 2.34 (95% CI 1.20-4.80). CONCLUSION: This study confirms differences in the reproductive pattern and LBW depending on maternal country of origin. These results allow a better understanding of the reproductive pattern and the implications of mothers' country of origin in LBW. Thus, helping health decisions makers to plan future health interventions aimed at reducing the LBW prevalence in Spain.

Estimating the prevalence of drug injection using a multiplier method based on a register of new HIV diagnoses.

Knowledge of prevalence of illegal drug injection can aid the design and evaluation of services for problem drug users. In this study, prevalence of recent injectors in Spain was estimated with a multiplier method using the number of injectors in a population register of new HIV diagnoses, HIV incidence among injectors from cohort studies and HIV prevalence among injectors in a drug treatment register. Prevalence in 2008 was 38.8 (95% CI 23.8-53.8) per 100,000 population, a 2.8 times reduction compared with 2001. This method permits estimation of both prevalence and trends of drug injection. It is sustainable and routinely applicable in many countries.

Excess of maternal mortality in foreign nationalities in Spain, 1999-2006.

OBJECTIVE: This study aimed to compare maternal mortality by province, autonomous region and mother's country of birth in Spain during 1999-2006. STUDY DESIGN: A cross-sectional ecological study with all live births and maternal mortality cases occurring during 1999-2006 in Spain was done. Data were drawn from the National Statistics Institute (INE) and we used the Movement of Natural Persons (MNP) and death statistics broken down by cause of death. Maternal mortality rates by province, autonomous region and mother's country of birth were calculated. To compare maternal mortality by province, standardised mortality ratios were calculated using an indirect standardisation. The risk of maternal death by autonomous region, age and mother's country of birth was calculated by a Poisson regression. RESULTS: Sub-Saharan nationalities present the highest maternal mortality rates. Adjusted by age and autonomous region, foreign nationalities had 67% higher risk of maternal mortality (RR=1.67; 95%CI=1.22-2.33). Adjusted by mother's country of birth and age, two autonomous regions had a significant mortality excess: Andalusia (RR=1.84; 95%CI=1.32-2.57) and Asturias (RR=2.78 95%CI=1.24-6.24). CONCLUSION: This study shows inequalities in maternal mortality by province, autonomous region and mother's country of birth in Spain. It would be desirable to implement a maternal mortality active surveillance system and the use of confidential qualitative surveys for analysis of socio-economic and healthcare circumstances surrounding deaths. These measures would be invaluable for in-depth understanding and characterisation of a preventable phenomenon such as maternal death.

Estimating the influenza vaccine effectiveness in elderly on a yearly basis using the Spanish influenza surveillance network--pilot case-control studies using different control groups, 2008-2009 season, Spain.

We conducted a case-control and screening method studies to estimate influenza vaccine effectiveness (IVE) in the age group >or=65 years, based on the Spanish Influenza Sentinel Surveillance System (SISSS). Cases (influenza laboratory-confirmed) were compared to influenza-negative ILI patients (test-negative) and patients without ILI since the beginning of the season (non-ILI). For the screening method, cases' vaccination coverage was compared to the vaccination coverage of the GPs' catchment population. The results suggested a protective effect of the vaccine against laboratory-confirmed influenza in elderly in 2008-2009. The screening method and the test-negative control designs enable estimating IVE using exclusively SISSS data.

[Seroprevalence study of hepatitis B among orienteers]. / Estudio de seroprevalencia de hepatitis B en deportistas de orientación.

BACKGROUND AND OBJECTIVE: Our objectives were to detect asymptomatic cases involved in an outbreak of hepatitis B, to assess the seroprevalence of hepatitis B (HB) in orienteers and to establish recommendations. PATIENTS AND METHOD: One hundred sixteen orienteers who had competed in the categories involved in the previous outbreak as well as a stratified random sample of 166 of the remaining orienteers in other competition categories were included in a cross-sectional serological prevalence study. HB surface antigen (anti-HBs); total antibody to HB core antigen (total anti-HBc); HB surface antigen (Ag HBs); and antibody IgM to HB core antigen (anti-HBcIgM) along with the history of vaccination for hepatitis B were analyzed. The results were weighted. RESULTS: The seroprevalence of HB (total anti-HBc positive) was 6.7% (n=12, 95% CI 0.6-12.9). No case of acute HB or chronic infection was observed. All the serological markers were negative for 61.1% (n=64, 95% CI 46.3-75.6), and 31.5% (n=29, 95% CI 18.2-46.4) had markers of immunity due to vaccination. Among individuals under 25 years of age, 28.4% were unvaccinated, although they were covered by vaccination programs. CONCLUSION: Our results suggest that the seroprevalence of HB among orienteers is not different from the general population in Spain. However, it is necessary to reinforce the vaccination among adolescents and young adults. General recommendations for the prevention of HB were made to orienteering federations.

Major reduction in AIDS-mortality inequalities after HAART: the importance of absolute differences in evaluating interventions.

This study estimates the magnitude of inequalities in AIDS mortality in the period when highly active antiretroviral therapy (HAART) was introduced and after its widespread dissemination in the Region of Madrid, Spain. Two population cohorts were constructed by linking records from 1996 and 2001 population censuses with mortality registry records after initial and full implementation of HAART, respectively. Absolute and relative differences in AIDS mortality in people aged 20-49 years were estimated in each population cohort according to neighbourhood and individual socioeconomic position. The absolute difference in mortality between neighbourhoods with highest and lowest socioeconomic position (unemployment rate, per capita income) declined from about 30/100,000 person-years in the 1996 population cohort to 8/100,000 person-years in the 2001 population cohort. The absolute difference in mortality between individuals with the highest and lowest socioeconomic position fell from about 60/100,000 person-years in the first cohort to about 20/100,000 in the second. Relative differences in mortality by neighbourhood socioeconomic position and by individual education level also decreased in the 2001 cohort with respect to the 1996 cohort. Although relative differences by individual occupation increased, there was no evidence of a significant change. These findings show major reduction in absolute socioeconomic differences in AIDS mortality after HAART and indicate that the use of relative differences alone may be inadequate to fully evaluate the results of health interventions.

[Role of antiretroviral therapy in the reduction of the association between low educational level and AIDS-related mortality]. / Papel del tratamiento antirretroviral en la reducción de la asociación entre nivel educativo bajo y mortalidad por sida.

BACKGROUND AND OBJECTIVE: AIDS-related mortality has been classically associated with lowest socioeconomic groups. In Spain, the highly active antiretroviral therapy (HAART) is delivered without cost; therefore this treatment it should have reduced the great social inequalities in AIDS-mortality seen before the HAART era. This study aims to assess the absolute and relative socioeconomic differences in AIDS-mortality in the Region of Madrid after the introduction of HAART. PATIENTS AND METHOD: Two twenty-months cohorts were created, in 1996 and 2001, which correspond to an early and late HAART-era respectively. Absolute and relative differences in the AIDS-mortality rates were calculated for both periods using generalized linear models. RESULTS: Absolute differences between the lowest and highest education level AIDS-related deaths decreased around 70% in the 2001 cohort. Those with lowest education level achieved the highest reduction rate, hence relative differences descended as well. CONCLUSIONS: HAART has had an essential role in decreasing social inequalities in AIDS-mortality.

[Descriptive epidemiology of non-meningococcal bacterial meningitis in the province of Saragossa [Spain] from 1999 to 2004. Evaluation of the Epidemiological Surveillance System]. / Epidemiología descriptiva de meningitis no meningocócicas bacterianas de la provincia de Zaragoza (1999-2004). Evaluación de su sistema de vigilancia.

OBJECTIVES: To describe non-meningococcal bacterial meningitis (nMM) and to evaluate the Epidemiological Surveillance System (ESS) in the province of Saragossa (Spain) between 1999 and 2004. METHODS: Information was obtained from the register of diseases subject to mandatory reporting and the Minimum Basic Data Set (MBDS). The ESS was evaluated by using the Centers for Disease Control and Prevention (CDC) criteria and by estimating the completeness of the system through the capture-recapture technique. RESULTS: 111 cases of nMM were notified (62.2% in males) and the mean age was 40.7 years. The largest proportion of cases (16.5%) occurred in children under 2 years of age. The clinical presentation was meningitis in 81.1%. Diagnosis was through bacterial culture in 70.3%. Streptococcus sp. was found in 54% (82% due to S. pneumoniae), enterobacteria in 5.4%, Listeria and Staphylococcus in 4.5%, Pseudomonas aeruginosa in 1.8%, and Haemophilus influenzae in 0.9%. The incidence rate per 100,000 inhabitants was 1.6 in 2004 and 2.6 in 2001. The case fatality was 7.3%. The completeness of the mandatory reporting system reached a peak in 2004 at 84.4%. The combined completeness of the MBDS and the mandatory reporting system was above 85% and timeliness of reporting was 2 days. The acceptability of the system was high since 75% of all variables were complete in 97% of the questionnaires. CONCLUSION: We highlight the importance of evaluation of the ESS, based on its results. nMM due to S. pneumoniae represent an important group of diseases and their case fatality is high. The completeness of the ESS in Saragossa was over 80% when the mandatory reporting system and the MBDS were combined. Incorporating the MBDS into surveillance would facilitate the estimation of the real incidence of various diseases subject to mandatory reporting.

Impact of flu on hospital admissions during 4 flu seasons in Spain, 2000-2004.

BACKGROUND: Seasonal flu epidemics in the European region cause high numbers of cases and deaths. Flu-associated mortality has been estimated but morbidity studies are necessary to understand the burden of disease in the population. Our objective was to estimate the excess hospital admissions in Spain of diseases associated with influenza during four epidemic influenza periods (2000-2004). METHODS: Hospital discharge registers containing pneumonia, chronic bronchitis, heart failure and flu from all public hospitals in Spain were reviewed for the years 2000 to 2004. Epidemic periods were defined by data from the Sentinel Surveillance System. Excess hospitalisations were calculated as the difference between the average number of weekly hospitalisations/100,000 in epidemic and non-epidemic periods. Flu epidemics were defined for seasons 2001/2002, 2002/2003, 2003/2004. RESULTS: A(H3N2) was the dominant circulating serotype in 2001/2002 and 2003/2004. Negligible excess hospitalisations were observed during the 2002/2003 epidemic where A(H1N1) was circulating. During 2000/2001, flu activity remained below threshold levels and therefore no epidemic period was defined. In two epidemic periods studied a delay between the peak of the influenza epidemic and the peak of hospitalisations was observed. During flu epidemics with A(H3N2), excess hospitalisations were higher in men and in persons <5 and >64 years higher than 10 per 100,000. Pneumonia accounted for 70% of all flu associated hospitalisations followed by chronic bronchitis. No excess flu-specific hospitalisations were recorded during all seasons. CONCLUSION: Flu epidemics have an impact on hospital morbidity in Spain. Further studies that include other variables, such as temperature and humidity, are necessary and will deepen our understanding of the role of each factor during flu epidemics and their relation with morbidity.

[Gastroenteritis outbreak in tourists: limitations of information and response]. / Brote de gastroenteritis en turistas: limitaciones de información y respuesta.

BACKGROUND: We present the results of different studies performed in the investigation of a gastroenteritis outbreak and we describe the difficulties and limitations encountered during its study. METHODS: Several analytical studies were designed: one cohort study and one case-control study with different samples sizes. RESULTS: Of the 189 trip participants, 43% answered the questionnaire. Forty-five cases were identified. The factors significantly associated with the disease were: dinner in one of the restaurants of the resort on December 11 in all analytical studies and the excursion to a nearby island in the cohort study. DISCUSSION: The outbreak was confirmed however due to the low response rate and the problems encountered to interview the participants in the trip, it was not possible to identify the route of transmission.

The role of the public health official in communicating public health information.

The prevailing views on the role of public health professionals refer to professionals in the academic world, without taking into account the fact that many public health professionals are government employees. For example, the American Public Health Association states that public health professionals play an active role in communicating public health information to nonscientific audiences, such as the general population or the mass media. We propose that public health officials have an important responsibility to promote the practice of public health. However, they must do so within the bureaucracy. Any actions that public health officials wish to take as advocates of particular public health activities should be carried out independent of their role as government officials.

[Influenza surveillance. New solutions to an old problem]. / La vigilancia de la gripe. Nuevas soluciones a un viejo problema.

The pandemic potential of influenza has made this disease the principal target of both national and international surveillance systems. The intrinsic characteristics of sentinel networks enable them to integrate epidemiological and virological information of a high incidence disease such as influenza, so helping in the early detection and characterization of the circulating influenza viruses and in evaluating their spread capacity in the population. A sentinel network, which covers 75% of the population, was created in Spain more than ten years ago. This provides a new approach to human influenza surveillance based on the individualized reporting of each case and the linkage of clinical, epidemiological and virological data. This system has contributed to a more accurate evaluation of influenza activity in Spain. In spite of the limitations of this sentinel system, which mainly derive from the lack of representativeness that any surveillance system based on population samples can encounter, it provides data which have proved useful for the follow-up and control of influenza. Rapid information transmission is one of the main advantages of the system, allowing its integration in the international disease surveillance networks and improving the timeliness of both information spread and formulation of recommendations.