Molecular characteristics of outbreaks of nosocomial infection with influenza A/H3N2 virus variants

Real-time investigation of an influenza A(H3N2) virus outbreak in a refugee community, November 2022

OBJECTIVES

To report epidemiological and virological results of an outbreak investigation of influenza-like illness (ILI) among refugees in Northern Italy.

STUDY DESIGN

Outbreak investigation of ILI cases observed among nearly 100 refugees in Northern Italy unvaccinated for influenza.

METHODS

An epidemiological investigation matched with a differential diagnosis was carried out for each sample collected from ILI cases to identify 10 viral pathogens (SARS-CoV-2, influenza virus type A and B, respiratory syncytial virus, metapneumovirus, parainfluenza viruses, rhinovirus, enterovirus, parechovirus, and adenovirus) by using specific real-time PCR assays according to the Centers for Disease Control and Prevention (CDC) protocols. In cases where the influenza virus type was identified, complete hemagglutinin (HA) gene sequencing and the related phylogenetic analysis were conducted.

RESULTS

The outbreak was caused by influenza A(H3N2): the attack rate was 83.3% in children aged 9-14 years, 84.6% in those aged 15-24 years, and 28.6% in adults ≥25 years. Phylogenetic analyses uncovered that A(H3N2) strains were closely related since they segregated in the same cluster, showing both a high mean nucleotide identity (100%), all belonging to the genetic sub-group 3C.2a1b.2a.2, as those mainly circulating into the general population in the same period.

CONCLUSIONS

The fact that influenza outbreak strains as well as the community strains were genetically related to the seasonal vaccine strain suggests that if an influenza prevention by vaccination strategy had been implemented, a lower attack rate of A(H3N2) and ILI cases might have been achieved.

Increasing influenza vaccination coverage in healthcare workers: analysis of an intensified on-site vaccination campaign during the COVID-19 pandemic

PURPOSE

Influenza infections have substantial impact on healthcare institutions. While vaccination is the most effective preventive measure against influenza infection, vaccination coverage in healthcare workers is low. The study investigates the impact of an intensified influenza vaccination campaign in a maximum-care hospital on influenza vaccination coverage in healthcare workers during the COVID-19 pandemic in 2020/21.

METHODS

Building on findings from our previously published review Schumacher et al. (Infection 49(3): 387, 2021), an intensified influenza vaccination campaign comprising a mobile vaccination team providing on-site vaccination and vaccination at a recurring central vaccination site in addition to promotional measures was performed and analysed regarding vaccination coverage. A survey querying vaccination motivation was performed. Campaign strategies and vaccination coverage of influenza seasons between 2017/18 and 2019/20 were analysed.

RESULTS

The influenza vaccination campaign 2020/21 led to a significant 2.4-fold increase yielding an overall vaccination coverage of 40% among healthcare workers. A significant increase in vaccination coverage was observed across all professional fields; especially among nurses, a 2.7-fold increase, reaching a vaccination coverage of 48%, was observed. The COVID-19 pandemic positively influenced vaccination decision in 72% of first time ever or first time in over ten years influenza vaccinees. Vaccination coverage during prior vaccination campaigns focusing on educational measures did not exceed 17%.

CONCLUSION

A mobile vaccination team providing on-site vaccination and vaccinations at a central vaccination site in addition to promotional measures can be implemented to increase influenza vaccination coverage in healthcare workers. Our concept can inform influenza and other vaccination campaigns for healthcare workers.

Uptake rates, knowledge, attitudes, and practices toward seasonal influenza vaccination among healthcare workers in Lebanon

Despite recommendations and their occupational risk to influenza infection vaccine hesitancy remains a challenge among healthcare workers (HCWs). No studies have been conducted in Lebanon to assess the influenza vaccine's acceptance among HCWs. We conducted a survey to assess factors associated with vaccine uptake and practices among HCWs in Lebanon. Only 40.4% of the HCWs reported receiving the 2018-2019 seasonal vaccine and 1 out 5 routinely received the seasonal vaccine. One-third of the HCWs reported having free access to the influenza vaccine. The willingness to receive the vaccine decreased had it been offered for a fee. Self, family and community protection (55.5%) was a key vaccination enabler. While, viral evolution, concerns regarding vaccine efficacy and side effects, and cost of vaccine ranked as top vaccination barriers. The majority of the HCWs (75%) recommended the vaccine to their patients. Past influenza vaccination (Odds ratio (OR) = 2.37, CI 1.48,3.79), willingness to receive the vaccine for free (OR = 6.93, CI 4.27-11.34) or having diagnosed influenza (OR = 1.81, CI 1.12-2.92) were significantly associated with HCWs' willingness to recommend the vaccine to patients. Better knowledge about influenza and vaccination was strongly associated with the willingness to receive and recommend the vaccine (p < .001). The vaccination rate among HCWs in Lebanon was suboptimal despite the positive attitudes toward the influenza vaccine. Interventions that enhance vaccine accessibility and knowledge are warranted to improve vaccination coverage among HCWs.

Response of gene regulatory networks after infection of H3N2 virus

Viral infection is a complicated dynamic process, in which viruses intrude into cells to duplicate themselves and trigger succeeding biological processes regulated by genes. It may lead to a serious disaster to human's health. A scheme is proposed to monitor the response of cells after being infected by viruses. Co-expression levels of genes measured at successive time points form a gene expression profile sequence, which is mapped to a temporal gene regulatory network. The fission and fusion of the communities of the networks are used to find the active parts. We investigated an experiment of injection of flu viruses into a total of 17 healthy volunteers, which develop into an infected group and a survival group. The survival group is much more chaotic, i.e. there occur complicated fissions and fusions of communities over the whole network. For the infected group, the most active part of the regulatory network forms a single community, but it is included in one of the large communities and completely conservative in the survival group. There are a total of six and seven genes in the active structure that take part in the Parkinson's disease and the ribosome pathways, respectively. Actually, a total of 30 genes (covering [Formula: see text]) of the genes in the active structure participate in the neuro-degeneration and its related pathways. This scheme can be extended straightforwardly to extract characteristics of trajectories of complex systems.

Development of cycling probe based real-time PCR methodology for influenza A viruses possessing the PA/I38T amino acid substitution associated with reduced baloxavir susceptibility

Baloxavir marboxil has been used for influenza treatment since March 2018 in Japan. After baloxavir treatment, the most frequently detected substitution is Ile38Thr in polymerase acidic protein (PA/I38T), and this substitution reduces baloxavir susceptibility in influenza A viruses. To rapidly investigate the frequency of PA/I38T in influenza A (H1N1)pdm09 and A (H3N2) viruses in clinical samples, we established a rapid real-time system to detect single nucleotide polymorphisms in PA, using cycling probe real-time PCR. We designed two sets of probes that were labeled with either 6-carboxyfluorescein (FAM) or 6-carboxy-X-rhodamine (ROX) to identify PA/I38 (wild type strain) or PA/I38T, respectively. The established cycling probe real-time PCR system showed a dynamic linear range of 10¹ to 10⁶ copies with high sensitivity in plasmid DNA controls. This real-time PCR system discriminated between PA/I38T and wild type viruses well. During the 2018/19 season, 377 influenza A-positive clinical samples were collected in Japan before antiviral treatment. Using our cycling probe real-time PCR system, we detected no (0/129, 0.0%) influenza A (H1N1)pdm09 viruses with PA/I38T substitutions and four A (H3N2) (4/229, 1.7%) with PA/I38T substitution prior to treatment. In addition, we found PA/I38T variant in siblings who did not received baloxavir treatment during an infection caused by A (H3N2) that afflicted the entire family. Although human-to-human transmission of PA/I38T variant may have occurred in a closed environment, the prevalence of this variant in influenza A viruses was still limited. Our cycling probe-PCR system is thus useful for antiviral surveillance of influenza A viruses possessing PA/I38T.

Detection of influenza virus in air samples of patient rooms

BACKGROUND

Understanding the transmission and dispersal of influenza virus and respiratory syncytial virus (RSV) via aerosols is essential for the development of preventative measures in hospital environments and healthcare facilities.

METHODS

During the 2017-2018 influenza season, patients with confirmed influenza or RSV infections were enrolled. Room air samples were collected close (0.30 m) to and distant (2.20 m) from patients' heads. Real-time polymerase chain reaction was used to detect and quantify viral particles in the air samples. The plaque assay was used to determine the infectiousness of the detected viruses.

FINDINGS

Fifty-one air samples were collected from the rooms of 29 patients with laboratory-confirmed influenza; 51% of the samples tested positive for influenza A virus (IAV). Among the IAV-positive patients, 65% were emitters (had at least one positive air sample), reflecting a higher risk of nosocomial transmission compared with non-emitters. The majority (61.5%) of the IAV-positive air samples were collected 0.3 m from a patient's head, while the remaining IAV-positive air samples were collected 2.2 m from a patient's head. The positivity rate of IAV in air samples was influenced by distance from the patient's head and day of sample collection after hospital admission. Only three patients with RSV infection were recruited and none of them were emitters.

CONCLUSION

Influenza virus can be aerosolized beyond 1 m in patient rooms, which is the distance considered to be safe by infection control practices. Further investigations are needed to determine the extent of infectivity of aerosolized virus particles.

Analytical and clinical evaluation of a point-of-care molecular diagnostic system and its influenza A/B assay for rapid molecular detection of the influenza virus

Recently, rapid molecular detection systems have been used for point-of-care testing for the diagnosis of influenza worldwide. Here, we evaluated the performance of the cobas Liat system and the cobas Influenza A/B assay (Liat) using fresh nasopharyngeal samples collected from a Japanese population between December 2017 and February 2018. The performance of the examination was compared with that of antigen testing and a conventional polymerase chain reaction (nested-PCR) method. A total of 159 patients were included in this study, and 77 tested positive using Liat. The concordance rate between Liat and nested PCR was 97.5%. The median time between the ordering of testing and completion of molecular analyses using Liat was 30 min (interquartile range: 28-35 min). The overall sensitivity and specificity of antigen testing were 57.1% and 100%, respectively. The duration from symptom onset to examination did not alter antigen testing sensitivity. The current study demonstrates the high performance of Liat for the rapid molecular identification of the influenza virus.

Intra-host and intra-household diversity of influenza A viruses during household transmissions in the 2013 season in 2 peri-urban communities of South Africa

Limited information is available on influenza virus sequence drift between transmission events. In countries with high HIV burdens, like South Africa, the direct and indirect effect of HIV on influenza sequence drift between transmission events may be of public health concern. To this end, we measured hemagglutinin sequence diversity between influenza transmission events using data and specimens from a study investigating household transmission dynamics of seasonal influenza viruses in 2 peri-urban communities in South Africa during the 2013 influenza season. Thirty index cases and 107 of 110 eligible household contacts were enrolled into the study, 47% (14/30) demonstrating intra-household laboratory-confirmed influenza transmission. In this study 35 partial hemagglutinin gene sequences were obtained by Sanger sequencing from 11 index cases (sampled at enrolment only) and 16 secondary cases (8 cases sampled at 1 and 8 cases sampled at 2 time-points). Viral sequence identities confirmed matched influenza transmission pairs within the 11 households with corresponding sequenced index and secondary cases. Phylogenetic analysis revealed 10 different influenza viral lineages in the 14 households. Influenza A(H1N1)pdm09 strains were shown to be genetically distinct between the 2 communities (from distinct geographic regions), which was not observed for the influenza A(H3N2) strains. Intra-host/intra-household influenza A(H3N2) sequence drift was identified in 2 households. The first was a synonymous mutation between the index case and a household contact, and the second a non-synonymous mutation between 2 serial samples taken at days 0 and 4 post enrolment from an HIV-infected secondary case. Limited inter-household sequence diversity was observed as highlighted by sharing of the same influenza strain between different households within each community. The limited intra-household sequence drift is in line with previous studies also using Sanger sequencing, corroborating the presence of strict selective bottlenecks that limit sequence variance. We were not able to directly ascertain the effect of HIV on influenza sequence drift between transmission events.

Mandatory influenza vaccination for all healthcare personnel: a review on justification, implementation and effectiveness

PURPOSE OF REVIEW

As healthcare-associated influenza is a serious public health concern, this review examines legal and ethical arguments supporting mandatory influenza vaccination policies for healthcare personnel, implementation issues and evidence of effectiveness.

RECENT FINDINGS

Spread of influenza from healthcare personnel to patients can result in severe harm or death. Although most healthcare personnel believe that they should be vaccinated against seasonal influenza, the Centers for Disease Control and Prevention (CDC) report that only 79% of personnel were vaccinated during the 2015-2016 season. Vaccination rates were as low as 44.9% in institutions that did not promote or offer the vaccine, compared with rates of more than 90% in institutions with mandatory vaccination policies. Policies that mandate influenza vaccination for healthcare personnel have legal and ethical justifications. Implementing such policies require multipronged approaches that include education efforts, easy access to vaccines, vaccine promotion, leadership support and consistent communication emphasizing patient safety.

SUMMARY

Mandatory influenza vaccination for healthcare personnel is a necessary step in protecting patients. Patients who interact with healthcare personnel are often at an elevated risk of complications from influenza. Vaccination is the best available strategy for protecting against influenza and evidence shows that institutional policies and state laws can effectively increase healthcare personnel vaccination rates, decreasing the risk of transmission in healthcare settings. There are legal and ethical precedents for institutional mandatory influenza policies and state laws, although successful implementation requires addressing both administrative and attitudinal barriers.

Influenza in long-term care facilities

Long-term care facility environments and the vulnerability of their residents provide a setting conducive to the rapid spread of influenza virus and other respiratory pathogens. Infections may be introduced by staff, visitors or new or transferred residents, and outbreaks of influenza in such settings can have devastating consequences for individuals, as well as placing extra strain on health services. As the population ages over the coming decades, increased provision of such facilities seems likely. The need for robust infection prevention and control practices will therefore remain of paramount importance if the impact of outbreaks is to be minimised. In this review, we discuss the nature of the problem of influenza in long-term care facilities, and approaches to preventive and control measures, including vaccination of residents and staff, and the use of antiviral drugs for treatment and prophylaxis, based on currently available evidence.

Influenza-like illness outbreaks in nursing homes in Corsica, France, 2014-2015: epidemiological and molecular characterization

Background

To study the molecular epidemiology of the influenza outbreaks in nursing homes (NHs) to determine whether multiple influenza strains were involved.

Methods

From September to December 2014, NHs in Corsica were invited to participate in an ongoing daily epidemiological and microbiological surveillance for influenza-like illness (ILI) among residents and health care workers (HCWs).

Results

The study involved 12 NHs. Respiratory illness meeting the ILI case definition was observed among 44 residents from whom 22 specimens were collected. Of the 22 residents with a nasopharyngeal sample, 13 (59 %) were positive for at least one of the 11 pathogens analysed. Among these 13 patients, 11 (92 %) presented a confirmed influenza (A/H3N2) and two had another respiratory virus: one human metapneumovirus and one human coronavirus. Of patients with a confirmed influenza A(H3N2), 10 (91 %) were vaccinated against influenza during the 2014–2015 season. Two influenza outbreaks were reported in two NHs, caused by influenza A(H3N2) strains belonging to cluster 3C.3 and 3C.2a. Although antivirals were available, prophylaxis was not used.

Conclusions

Phylogenetic analysis seems to suggest no multiple introduction into the two NHs reporting the two influenza A(H3N2) outbreaks. A number of factors could have contributed to transmitting influenza in NHs including, the absence of administration of antiviral treatment for prophylaxis of all residents/staff regardless of immunization status because of the poor vaccine match during each outbreak, the intensive contacts with incompletely protected residents and HCWs, and the low adherence of NHs to notification of ILI outbreaks to the health authorities.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2957-z) contains supplementary material, which is available to authorized users.

Molecular diagnosis of respiratory viruses

The increasing availability of nucleic acid amplification tests since the 1980s has revolutionised our understanding of the pathogenesis, epidemiology, clinical and laboratory aspects of known and novel viral respiratory pathogens. High-throughput, multiplex polymerase chain reaction is the most commonly used qualitative detection method, but utilisation of newer techniques such as next-generation sequencing will become more common following significant cost reductions. Rapid and readily accessible isothermal amplification platforms have also allowed molecular diagnostics to be used in a ‘point-of-care’ format. This review focuses on the current applications and limitations of molecular diagnosis for respiratory viruses.

Combining high-resolution contact data with virological data to investigate influenza transmission in a tertiary care hospital

OBJECTIVE

Contact patterns and microbiological data contribute to a detailed understanding of infectious disease transmission. We explored the automated collection of high-resolution contact data by wearable sensors combined with virological data to investigate influenza transmission among patients and healthcare workers in a geriatric unit.

DESIGN

Proof-of-concept observational study. Detailed information on contact patterns were collected by wearable sensors over 12 days. Systematic nasopharyngeal swabs were taken, analyzed for influenza A and B viruses by real-time polymerase chain reaction, and cultured for phylogenetic analysis.

SETTING

An acute-care geriatric unit in a tertiary care hospital.

PARTICIPANTS

Patients, nurses, and medical doctors.

RESULTS

A total of 18,765 contacts were recorded among 37 patients, 32 nurses, and 15 medical doctors. Most contacts occurred between nurses or between a nurse and a patient. Fifteen individuals had influenza A (H3N2). Among these, 11 study participants were positive at the beginning of the study or at admission, and 3 patients and 1 nurse acquired laboratory-confirmed influenza during the study. Infectious medical doctors and nurses were identified as potential sources of hospital-acquired influenza (HA-Flu) for patients, and infectious patients were identified as likely sources for nurses. Only 1 potential transmission between nurses was observed.

CONCLUSIONS

Combining high-resolution contact data and virological data allowed us to identify a potential transmission route in each possible case of HA-Flu. This promising method should be applied for longer periods in larger populations, with more complete use of phylogenetic analyses, for a better understanding of influenza transmission dynamics in a hospital setting.

Phylogenetic Exploration of Nosocomial Transmission Chains of 2009 Influenza A/H1N1 among Children Admitted at Red Cross War Memorial Children's Hospital, Cape Town, South Africa in 2011

Traditional modes of investigating influenza nosocomial transmission have entailed a combination of confirmatory molecular diagnostic testing and epidemiological investigation. Common hospital-acquired infections like influenza require a discerning ability to distinguish between viral isolates to accurately identify patient transmission chains. We assessed whether influenza hemagglutinin sequence phylogenies can be used to enrich epidemiological data when investigating the extent of nosocomial transmission over a four-month period within a paediatric Hospital in Cape Town South Africa. Possible transmission chains/channels were initially determined through basic patient admission data combined with Maximum likelihood and time-scaled Bayesian phylogenetic analyses. These analyses suggested that most instances of potential hospital-acquired infections resulted from multiple introductions of Influenza A into the hospital, which included instances where virus hemagglutinin sequences were identical between different patients. Furthermore, a general inability to establish epidemiological transmission linkage of patients/viral isolates implied that identified isolates could have originated from asymptomatic hospital patients, visitors or hospital staff. In contrast, a traditional epidemiological investigation that used no viral phylogenetic analyses, based on patient co-admission into specific wards during a particular time-frame, suggested that multiple hospital acquired infection instances may have stemmed from a limited number of identifiable index viral isolates/patients. This traditional epidemiological analysis by itself could incorrectly suggest linkage between unrelated cases, underestimate the number of unique infections and may overlook the possible diffuse nature of hospital transmission, which was suggested by sequencing data to be caused by multiple unique introductions of influenza A isolates into individual hospital wards. We have demonstrated a functional role for viral sequence data in nosocomial transmission investigation through its ability to enrich traditional, non-molecular observational epidemiological investigation by teasing out possible transmission pathways and working toward more accurately enumerating the number of possible transmission events.

Influenza among afebrile and vaccinated healthcare workers

Background. To prevent transmission of influenza from healthcare workers (HCWs) to patients, many hospitals exclude febrile HCWs from working, but allow afebrile HCWs with respiratory symptoms to have contact with patients. During the 2013–2014 influenza season at our hospital, an influenza-positive HCW with respiratory symptoms but no fever was linked to a case of possible healthcare-associated influenza in a patient. Therefore, we implemented a temporary policy of mandatory influenza testing for HCWs with respiratory symptoms.

Methods. From 3 January through 28 February 2014, we tested HCWs with respiratory symptoms for influenza and other respiratory pathogens by polymerase chain reaction of flocked nasopharyngeal swabs. HCWs also reported symptoms and influenza vaccination status, and underwent temperature measurement. We calculated the proportion of influenza-positive HCWs with fever and prior influenza vaccination.

Results. Of 449 HCWs, 243 (54%) had a positive test for any respiratory pathogen; 34 (7.6%) HCWs tested positive for influenza. An additional 7 HCWs were diagnosed with influenza by outside physicians. Twenty-one (51.2%) employees with influenza had fever. Among influenza-infected HCWs, 20 had previously received influenza vaccination, 18 had declined the vaccine, and 3 had unknown vaccination status. There was no significant difference in febrile disease among influenza-infected employees who had received the influenza vaccine and those who had not received the vaccine (45% vs 61%; P = .32).

Conclusions. Nearly half of HCWs with influenza were afebrile prior to their diagnosis. HCWs with respiratory symptoms but no fever may pose a risk of influenza transmission to patients and coworkers.

Framework for controlling infection through isolation precautions in Japan

In Japan, nurses certified in infection control face organizational and structural challenges to the implementation of the recommended isolation precautions. In this study, we developed a conceptual framework for the problem-solving process of certified nurses in infection control when implementing appropriate isolation-precaution measures. We conducted a qualitative, descriptive study using directed content analysis. Semistructured interviews were conducted with 40 nurses who had over five years' experience in infection control. Factors assessing the risk of infection in patients were identified, including microorganism characteristics, patient characteristics, and risk of infection to the entire unit. The nurses also assessed the risk of infection in institutions from the following perspectives: organizational culture, infection control system, human resources, environment surrounding the facility, ethical issues, and external factors. Individual characteristics, such as attributes, knowledge, expertise, and job function, were identified as major influencing factors in the problem-solving process. These findings could be useful for newly-certified nurses in infection control and provide recommendations on implementing isolation-precaution measures.

Nosocomial transmission of respiratory syncytial virus in an outpatient cancer center

Respiratory syncytial virus (RSV) outbreaks in inpatient settings are associated with poor outcomes in cancer patients. The use of molecular epidemiology to document RSV transmission in the outpatient setting has not been well described. We performed a retrospective cohort study of 2 nosocomial outbreaks of RSV at the Seattle Cancer Care Alliance. Subjects included patients seen at the Seattle Cancer Care Alliance with RSV detected in 2 outbreaks in 2007-2008 and 2012 and all employees with respiratory viruses detected in the 2007-2008 outbreak. A subset of samples was sequenced using semi-nested PCR targeting the RSV attachment glycoprotein coding region. Fifty-one cases of RSV were identified in 2007-2008. Clustering of identical viral strains was detected in 10 of 15 patients (67%) with RSV sequenced from 2007 to 2008. As part of a multimodal infection control strategy implemented as a response to the outbreak, symptomatic employees had nasal washes collected. Of 254 employee samples, 91 (34%) tested positive for a respiratory virus, including 14 with RSV. In another RSV outbreak in 2012, 24 cases of RSV were identified; 9 of 10 patients (90%) had the same viral strain, and 1 (10%) had another viral strain. We document spread of clonal strains within an outpatient cancer care setting. Infection control interventions should be implemented in outpatient, as well as inpatient, settings to reduce person-to-person transmission and limit progression of RSV outbreaks.

Routes of transmission during a nosocomial influenza A(H3N2) outbreak among geriatric patients and healthcare workers

BACKGROUND

Influenza presents a life-threatening infection for hospitalized geriatric patients, who might be nosocomially infected via healthcare workers (HCWs), other patients or visitors. In the 2011/2012 influenza season an influenza A(H3N2) outbreak occurred in the geriatric department at the Hôpital Edouard Herriot, Lyon.

AIM

To clarify the transmission chain for this influenza A(H3N2) outbreak by sequence analysis and to identify preventive measures.

METHODS

Laboratory testing of patients with influenza-like illness in the acute care geriatric department revealed 22 cases of influenza between 19th February and 15th March 2012. Incidences for patients and HCWs were calculated and possible epidemiological links were analysed using a questionnaire. Neuraminidase and haemagglutinin genes of culture-positive samples and community influenza samples were sequenced and clustered to detect patients with identical viral strains.

FINDINGS

Sixteen patients and six HCWs were affected, resulting in an attack rate of 24% and 11% respectively. Six nosocomial infections were recorded. The sequence analysis confirmed three independent influenza clusters on three different sections of the geriatric ward. For at least two clusters, an HCW source was determined.

CONCLUSION

Epidemiological and microbiological results confirm influenza transmission from HCWs to patients. A higher vaccination rate, isolation measures and better hand hygiene are recommended in order to prevent outbreaks in future influenza seasons.

Influenza outbreak control practices and the effectiveness of interventions in long-term care facilities: a systematic review

Background

Evaluation of influenza control measures frequently focuses on the efficacy of chemoprophylaxis and vaccination, while the effectiveness of non-pharmaceutical interventions (NPI) receives less emphasis. While influenza control measures are frequently reported for individual outbreaks, there have been few efforts to characterize the real-world effectiveness of these interventions across outbreaks.

Objectives

To characterize influenza case and outbreak definitions and control measures reported by long-term care facilities (LTCFs) of elderly adults and estimate the reduction in influenza-like illness (ILI) attack rates due to chemoprophylaxis and NPI.

Methods

We conducted a literature search in PubMed including English-language studies reporting influenza outbreaks among elderly individuals in LTCFs. A Bayesian hierarchical logistic regression model estimated the effects of control measures on ILI attack rates.

Results

Of 654 articles identified in the literature review, 37 articles describing 60 influenza outbreaks met the inclusion criteria. Individuals in facilities where chemoprophylaxis was used were significantly less likely to develop influenza A or B than those in facilities with no interventions [odds ratio (OR) 0·48, 95% CI: 0·28, 0·84]. Considered by drug class, adamantanes significantly reduced infection risk (OR 0·22, 95% CI: 0·12, 0·42), while neuraminidase inhibitors did not show a significant effect. Although NPI showed no significant effect, the results suggest that personal protective equipment may produce modest protective effects.

Conclusions

Our results indicate pharmaceutical control measures have the clearest reported protective effect in LTCFs. Non-pharmaceutical approaches may be useful; however, most data were from observational studies and standardized reporting or well-conducted clinical trials of NPI are needed to more precisely measure these effects.

Vaccinations for healthcare personnel: update on influenza, hepatitis B, and pertussis

PURPOSE OF REVIEW

Healthcare personnel (HCP) are at risk for exposure to and transmission of potentially life-threatening vaccine preventable diseases to patients and colleagues. The Centers for Disease Control and Advisory Committee on Immunization Practices (ACIP) recommend routine influenza immunization and maintenance of immunity to hepatitis B and pertussis, among others. In this article, we aim to review recently approved influenza vaccines, as well as address some of the issues regarding hepatitis B and pertussis vaccinations in HCP.

RECENT FINDINGS

Several new formulations of influenza vaccines are now available, including quadrivalent vaccines and non-egg-based vaccines; their use in HCP requires further study. An alarming rise in pertussis rates has led to a revision of ACIP guidelines recommending vaccination for women during each pregnancy. Persistent lack of immunity to hepatitis B after vaccine series remains a problem for many HCP.

SUMMARY

Inactivated trivalent influenza vaccines remain the safest and most widely studied influenza vaccinations for healthcare workers. A pertussis booster in the form of Tdap is now recommended for most HCP. More studies are needed regarding the issue of nonresponders in HCP who receive the three-dose hepatitis B vaccine series, as there are some promising strategies available that may boost immune responses.