A US postmarketing evaluation of the frequency and safety of live attenuated influenza vaccine use in nonrecommended children younger than 5 years: 2009-2010 season

Gaps in knowledge about the vaccine coverage of immunocompromised children: a scoping review

Immunocompromised children are at increased risk of severe illness from vaccine-preventable infections. However, inadequate vaccine coverage remains a concern. This scoping review sought to determine the current state of knowledge regarding vaccine coverage of immunocompromised children. Bibliographic databases were searched for primary research from any year. Data were analyzed quantitatively and narratively. Ninety-seven studies met inclusion criteria. The most commonly studied vaccines were pneumococcal (n = 46), influenza (n = 44), diphtheria/tetanus/pertussis/poliomyelitis/Haemophilus influenzae type B/hepatitis B-containing (n = 36), and measles- and/or mumps- and/or rubella-containing (n = 29). Immunocompromising conditions studied included cancer/stem cell transplants (n = 24), solid organ transplants (n = 23), sickle cell disease (n = 21), immunosuppressive therapy (n = 14), human immunodeficiency virus (n = 12), splenectomy (n = 4), and primary immunodeficiency (n = 2). As more children are treated with immunosuppressive therapies, it is critical to identify whether they are being appropriately vaccinated for age and condition. We identified gaps in the current state of knowledge for specific vaccine types in specific immunocompromised populations.

Safety of live attenuated influenza vaccine (LAIV) in children and adults with asthma: a systematic literature review and narrative synthesis

INTRODUCTION

Asthma is one of the most common chronic respiratory conditions worldwide and can be exacerbated by influenza. Findings from early trials demonstrated a higher risk of medically significant wheezing in otherwise healthy young children (aged 6 - 23 months) following administration of the Ann Arbor-backbone live attenuated influenza vaccine (LAIV-AA). In more recent years, several additional studies have investigated the safety of LAIV-AA in older children (2 - 17 years of age) and adults with asthma or prior wheezing, but these findings have not yet been systematically evaluated.

AREAS COVERED

We conducted a systematic literature review to assess and synthesize the evidence from all available studies on the safety of LAIV-AA in people aged 2 - 49 years with a diagnosis of asthma or recurrent wheezing.

EXPERT OPINION

Fourteen studies over 20 years, involving a total of 1.2 million participants, provided evidence that LAIV-AA was well tolerated with no safety concerns in individuals aged 2 - 49 years with a diagnosis of asthma or recurrent wheezing. These data can help inform guidelines for use of LAIV-AA in children and adults with a history of asthma or recurrent wheezing.

Safety of live attenuated influenza vaccine (LAIV) in children with moderate to severe asthma

BACKGROUND

Live attenuated influenza vaccine (LAIV) is recommended for annual influenza vaccination in children from age 2 years. However, some guidelines recommend against its use in children with asthma or recurrent wheeze due to concerns over its potential to induce wheezing.

OBJECTIVE

We sought to assess the safety of LAIV in children with moderate to severe asthma, and in preschool children with recurrent wheeze.

METHODS

Prospective, multicenter, open-label, phase IV intervention study in 14 specialist UK clinics. LAIV was administered under medical supervision, with follow-up of asthma symptoms 72 hours and 4 weeks late, using validated questionnaires.

RESULTS

A total of 478 young people (median, 9.3; range, 2-18 years) with physician-diagnosed asthma or recurrent wheeze were recruited, including 208 (44%) prescribed high-dose inhaled corticosteroids and 122 (31%) with severe asthma. There was no significant change in asthma symptoms in the 4 weeks after administration (median change, 0; P = .26, McNemar test), with no impact of level of baseline asthma control/symptoms in predicting either a worsening of asthma or exacerbation after LAIV using a regression model. A total of 47 subjects (14.7%; 95% CI, 11%-19.1%) reported a severe asthma exacerbation in the 4 weeks after immunization, requiring a short course of systemic corticosteroids; in 4 cases, this occurred within 72 hours of vaccination. No association with asthma severity, baseline lung function, or asthma control was identified.

CONCLUSIONS

LAIV appears to be well tolerated in the vast majority of children with asthma or recurrent wheeze, including those whose asthma is categorized as severe or poorly controlled.

Are we speaking the same language? an argument for the consistent use of terminology and definitions for childhood vaccination indicators

Vaccination indicators are used to measure the health status of individuals or populations and to evaluate the effectiveness of vaccination programs or policies. Ensuring that vaccination indicators are clearly and consistently defined is important for effective communication of outcomes, accurate program evaluation, and comparison between different populations, times, and contexts. The purpose of this commentary is to describe commonly used vaccination indicators and to highlight inconsistencies in how childhood vaccine researchers use and define these terms. The indicators we describe are vaccine coverage, uptake, and rate; vaccination status, initiation, and completion; and up-to-date, timely, partial, and incomplete vaccination. We conclude that many vaccination indicators are not explicitly defined within published research studies and/or are used quite differently across studies. We also note that the choice of indicator in a given study is often driven by program or vaccine specific factors, may be constrained by data availability, and should be chosen to best reflect the outcome of interest. We conclude that the use of consistent language and definitions would promote more effective communication of research findings. We also propose some standardized definitions for common indicators, with the goal of provoking discussion and debate on the issue.

Influenza vaccine: Where are we and where do we go?

The alarming rise of morbidity and mortality caused by influenza pandemics and epidemics has drawn attention worldwide since the last few decades. This life-threatening problem necessitates the development of a safe and effective vaccine to protect against incoming pandemics. The currently available flu vaccines rely on inactivated viral particles, M2e-based vaccine, live attenuated influenza vaccine (LAIV) and virus like particle (VLP). While inactivated vaccines can only induce systemic humoral responses, LAIV and VLP vaccines stimulate both humoral and cellular immune responses. Yet, these vaccines have limited protection against newly emerging viral strains. These strains, however, can be targeted by universal vaccines consisting of conserved viral proteins such as M2e and capable of inducing cross-reactive immune response. The lack of viral genome in VLP and M2e-based vaccines addresses safety concern associated with existing attenuated vaccines. With the emergence of new recombinant viral strains each year, additional effort towards developing improved universal vaccine is warranted. Besides various types of vaccines, microRNA and exosome-based vaccines have been emerged as new types of influenza vaccines which are associated with new and effective properties. Hence, development of a new generation of vaccines could contribute to better treatment of influenza.

Influenza vaccines: Evaluation of the safety profile

The safety of vaccines is a critical factor in maintaining public trust in national vaccination programs. Vaccines are recommended for children, adults and elderly subjects and have to meet higher safety standards, since they are administered to healthy subjects, mainly healthy children. Although vaccines are strictly monitored before authorization, the possibility of adverse events and/or rare adverse events cannot be totally eliminated. Two main types of influenza vaccines are currently available: parenteral inactivated influenza vaccines and intranasal live attenuated vaccines. Both display a good safety profile in adults and children. However, they can cause adverse events and/or rare adverse events, some of which are more prevalent in children, while others with a higher prevalence in adults. The aim of this review is to provide an overview of influenza vaccine safety according to target groups, vaccine types and production methods.

A multi-site feasibility study to assess fever and wheezing in children after influenza vaccines using text messaging

BACKGROUND

Using text messaging for vaccine safety monitoring, particularly for non-medically attended events, would be valuable for pandemic influenza and emergency vaccination program preparedness. We assessed the feasibility and acceptability of text messaging to evaluate fever and wheezing post-influenza vaccination in a prospective, observational, multi-site pediatric study.

METHODS

Children aged 2-11 years old, with an emphasis on children with asthma, were recruited during the 2014-2015 influenza season from three community-based clinics in New York City, and during the 2014-2015 and 2015-2016 seasons from a private practice in Fall River, Massachusetts. Parents of enrolled children receiving quadrivalent live attenuated (LAIV4) or inactivated influenza vaccine (IIV4) replied to text messages assessing respiratory symptoms (day 3 and 7, then weekly through day 42), and temperature on the night of vaccination and the next seven nights (day 0-7). Missing data were collected via diary (day 0-7 only) and phone. Phone confirmation was obtained for both presence and absence of respiratory symptoms. Reporting rates, fever (T≥100.4 °F) frequency, proportion of wheezing and/or chest tightness reports captured via text message versus all sources (text, phone, diary, electronic health record) and parental satisfaction were assessed.

RESULTS

Across both seasons, 266 children were analyzed; 49.2% with asthma. Parental text message response rates were high (>70%) across sites. Overall, fever frequency was low (day 0-2: 4.1% [95% confidence interval (CI) 2.3-7.4%]; d3-7: 6.7% [95% CI 4.1-10.8%]). A third (39.2%) of parents reported a respiratory problem in their child, primarily cough. Most (88.2%) of the 52 wheezing and/or chest tightness reports were by text message. Most (88.1%) participants preferred text messaging over paper reporting.

CONCLUSIONS

Text messaging can provide information about pediatric post-vaccination fever and wheezing and was viewed positively by parents. It could be a helpful tool for rapid vaccine safety monitoring during a pandemic or other emergency vaccination program.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02295007.

Live attenuated influenza vaccine use and safety in children and adults with asthma

BACKGROUND

Live attenuated influenza vaccine (LAIV) might increase the risk of wheezing in persons with asthma or children younger than 5 years with a history of recurrent wheezing.

OBJECTIVE

To describe the use and assess the safety of LAIV in persons with asthma in the Vaccine Safety Datalink population.

METHODS

We identified persons with asthma using diagnosis codes and medication records in 7 health care organizations over 3 influenza seasons (2008-2009 through 2010-2011) and determined their influenza vaccination rates. Using the self-controlled risk interval method, we calculated the incidence rate ratio of medically attended respiratory events in the 14 days after LAIV compared with 29 to 42 days after vaccination in persons 2 through 49 years old.

RESULTS

In our population of 6.3 million, asthma prevalence was 5.9%. Of persons with asthma, approximately 50% received any influenza vaccine but less than 1% received LAIV. The safety study included 12,354 LAIV doses (75% in children; 93% in those with intermittent or mild persistent asthma). The incidence rate ratio for inpatient and emergency department visits for lower respiratory events (including asthma exacerbation and wheezing) was 0.98 (95% confidence interval 0.63-1.51) and the incidence rate ratio for upper respiratory events was 0.94 (95% confidence interval 0.48-1.86). The risk of lower respiratory events was similar for intermittent and mild persistent asthma, across age groups, and for seasonal trivalent LAIV and 2009 H1N1 pandemic monovalent LAIV.

CONCLUSION

LAIV use in asthma was mostly in persons with intermittent or mild persistent asthma. LAIV was not associated with an increased risk of medically attended respiratory adverse events.

Asthma exacerbations among asthmatic children receiving live attenuated versus inactivated influenza vaccines

OBJECTIVE

To investigate whether there is a difference in the risk of asthma exacerbations between children with pre-existing asthma who receive live attenuated influenza vaccine (LAIV) compared with inactivated influenza vaccine (IIV).

MATERIAL AND METHODS

We identified IIV and LAIV immunizations occurring between July 1, 2007 and March 31, 2014 among Kaiser Permanente Northern California members aged 2 to <18years with a history of asthma, and subsequent asthma exacerbations seen in the inpatient or Emergency Department (ED) setting. We calculated the ratio of the odds (OR) of an exacerbation being in the risk interval (1-14days) versus the comparison interval (29-42days) following immunization, separately for LAIV and IIV, and then examined whether the OR differed between children receiving LAIV and those receiving IIV ("difference-in-differences").

RESULTS

Among 387,633 immunizations, 85% were IIV and 15% were LAIV. Children getting LAIV vs. IIV were less likely to have "current or recent, persistent" asthma (25% vs. 47%), and more likely to have "remote history" of asthma (47% vs. 25%). Among IIV-vaccinated asthmatic children, the OR of an inpatient/ED asthma exacerbation was 0.97 (95% CI: 0.82-1.15). Among LAIV-vaccinated asthmatic children the OR was 0.38 (95% CI: 0.17-0.90). In the difference-in-differences analysis, the odds of asthma exacerbation following LAIV were less than IIV (Ratio of ORs: 0.40, CI: 0.17-0.95, p value: 0.04).

CONCLUSION

Among children ≥2years old with asthma, we found no increased risk of asthma exacerbation following LAIV or IIV, and a decreased risk following LAIV compared to IIV.

The safety of influenza vaccines in children: An Institute for Vaccine Safety white paper

Most influenza vaccines are generally safe, but influenza vaccines can cause rare serious adverse events. Some adverse events, such as fever and febrile seizures, are more common in children than adults. There can be differences in the safety of vaccines in different populations due to underlying differences in genetic predisposition to the adverse event. Live attenuated vaccines have not been studied adequately in children under 2 years of age to determine the risks of adverse events; more studies are needed to address this and several other priority safety issues with all influenza vaccines in children. All vaccines intended for use in children require safety testing in the target age group, especially in young children. Safety of one influenza vaccine in children should not be extrapolated to assumed safety of all influenza vaccines in children. The low rates of adverse events from influenza vaccines should not be a deterrent to the use of influenza vaccines because of the overwhelming evidence of the burden of disease due to influenza in children.

Safety of live attenuated influenza vaccine in young people with egg allergy: multicentre prospective cohort study

STUDY QUESTION

How safe is live attenuated influenza vaccine (LAIV), which contains egg protein, in young people with egg allergy?

METHODS

In this open label, phase IV intervention study, 779 young people (2-18 years) with egg allergy were recruited from 30 UK allergy centres and immunised with LAIV. The cohort included 270 (34.7%) young people with previous anaphylaxis to egg, of whom 157 (20.1%) had experienced respiratory and/or cardiovascular symptoms. 445 (57.1%) had doctor diagnosed asthma or recurrent wheeze. Participants were observed for at least 30 minutes after vaccination and followed-up by telephone 72 hours later. Participants with a history of recurrent wheeze or asthma underwent further follow-up four weeks later. The main outcome measure was incidence of an adverse event within two hours of vaccination in young people with egg allergy.

STUDY ANSWER AND LIMITATIONS

No systemic allergic reactions occurred (upper 95% confidence interval for population 0.47% and in participants with anaphylaxis to egg 1.36%). Nine participants (1.2%, 95% CI 0.5% to 2.2%) experienced mild symptoms, potentially consistent with a local, IgE mediated allergic reaction. Delayed events potentially related to the vaccine were reported in 221 participants. 62 participants (8.1%, 95% CI for population 6.3% to 10.3%) experienced lower respiratory tract symptoms within 72 hours, including 29 with parent reported wheeze. No participants were admitted to hospital. No increase in lower respiratory tract symptoms occurred in the four weeks after vaccination (assessed with asthma control test). The study cohort may represent young people with more severe allergy requiring specialist input, since they were recruited from secondary and tertiary allergy centres.

WHAT THIS STUDY ADDS

LAIV is associated with a low risk of systemic allergic reactions in young people with egg allergy. The vaccine seems to be well tolerated in those with well controlled asthma or recurrent wheeze.

FUNDING, COMPETING INTERESTS, DATA SHARING

This report is independent research commissioned and funded by a Department of Health policy research programme grant to the National Vaccine Evaluation Consortium. Additional funding was provided by the NIHR Clinical Research Networks, Health Protection Scotland (Edinburgh site), and Health & Social Care Services in Northern Ireland (Belfast site). PJT and MEL had support from the Department of Health for the submitted work; PJT has received research grants from the Medical Research Council and NIHR. No additional data available.Study registration ClinicalTrials.gov (NCT02111512) and the EU Clinical Trials Register EudraCT (2014-001537-92).

Safety of live attenuated influenza vaccine in atopic children with egg allergy

Background

Live attenuated influenza vaccine (LAIV) is an intranasal vaccine recently incorporated into the United Kingdom immunization schedule. However, it contains egg protein and, in the absence of safety data, is contraindicated in patients with egg allergy. Furthermore, North American guidelines recommend against its use in asthmatic children.

Objective

We sought to assess the safety of LAIV in children with egg allergy.

Methods

We performed a prospective, multicenter, open-label, phase IV intervention study involving 11 secondary/tertiary centers in the United Kingdom. Children with egg allergy (defined as a convincing clinical reaction to egg within the past 12 months and/or >95% likelihood of clinical egg allergy as per published criteria) were recruited. LAIV was administered under medical supervision, with observation for 1 hour and telephone follow-up 72 hours later.

Results

Four hundred thirty-three doses were administered to 282 children with egg allergy (median, 4.9 years; range, 2-17 years); 115 (41%) had experienced prior anaphylaxis to egg. A physician's diagnosis of asthma/recurrent wheezing was noted in 67%, and 51% were receiving regular preventer therapy. There were no systemic allergic reactions (upper 95% CI for population, 1.3%). Eight children experienced mild self-limiting symptoms, which might have been due an IgE-mediated allergic reaction. Twenty-six (9.4%; 95% CI for population, 6.2% to 13.4%) children experienced lower respiratory tract symptoms within 72 hours, including 13 with parent-reported wheeze. None of these episodes required medical intervention beyond routine treatment.

Conclusions

In contrast to current recommendations, LAIV appears to be safe for use in children with egg allergy. Furthermore, the vaccine appears to be well tolerated in children with a diagnosis of asthma or recurrent wheeze.

Vaccination of children with a live-attenuated, intranasal influenza vaccine - analysis and evaluation through a Health Technology Assessment

BACKGROUND

Influenza is a worldwide prevalent infectious disease of the respiratory tract annually causing high morbidity and mortality in Germany. Influenza is preventable by vaccination and this vaccination is so far recommended by the The German Standing Committee on Vaccination (STIKO) as a standard vaccination for people from the age of 60 onwards. Up to date a parenterally administered trivalent inactivated vaccine (TIV) has been in use almost exclusively. Since 2011 however a live-attenuated vaccine (LAIV) has been approved additionally. Consecutively, since 2013 the STIKO recommends LAIV (besides TIV) for children from 2 to 17 years of age, within the scope of vaccination by specified indications. LAIV should be preferred administered in children from 2 to 6 of age. The objective of this Health Technology Assessment (HTA) is to address various research issues regarding the vaccination of children with LAIV. The analysis was performed from a medical, epidemiological and health economic perspective, as well as from an ethical, social and legal point of view.

METHOD

An extensive systematic database research was performed to obtain relevant information. In addition a supplementary research by hand was done. Identified literature was screened in two passes by two independent reviewers using predefined inclusion and exclusion criteria. Included literature was evaluated in full-text using acknowledged standards. Studies were graded with the highest level of evidence (1++), if they met the criteria of European Medicines Agency (EMA)-Guidance: Points to consider on applications with 1. meta-analyses; 2. one pivotal study.

RESULTS

For the medical section, the age of the study participants ranges from 6 months to 17 years. Regarding study efficacy, in children aged 6 months to ≤7 years, LAIV is superior to placebo as well as to a vac-cination with TIV (Relative Risk Reduction - RRR - of laboratory confirmed influenza infection approx. 80% and 50%, respectively). In children aged >7 to 17 years (= 18th year of their lives), LAIV is superior to a vaccination with TIV (RRR 32%). For this age group, no studies that compared LAIV with placebo were identified. It can be concluded that there is high evidence for superior efficacy of LAIV (compared to placebo or TIV) among children aged 6 months to ≤7 years. For children from >7 to 17 years, there is moderate evidence for superiority of LAIV for children with asthma, while direct evidence for children from the general population is lacking for this age group. Due to the efficacy of LAIV in children aged 6 months to ≤7 years (high evidence) and the efficacy of LAIV in children with asthma aged >7 to 17 years (moderate evidence), LAIV is also very likely to be efficacious among children in the general population aged >7 to 17 years (indirect evidence). In the included studies with children aged 2 to 17 years, LAIV was safe and well-tolerated; while in younger children LAIV may increase the risk of obstruction of the airways (e.g. wheezing). In the majority of the evaluated epidemiological studies, LAIV proved to be effective in the prevention of influenza among children aged 2-17 years under everyday conditions (effectiveness). The trend appears to indicate that LAIV is more effective than TIV, although this can only be based on limited evidence for methodological reasons (observational studies). In addition to a direct protective effect for vaccinated children themselves, indirect protective ("herd protection") effects were reported among non-vaccinated elderly population groups, even at relatively low vaccination coverage of children. With regard to safety, LAIV generally can be considered equivalent to TIV. This also applies to the use among children with mild chronically obstructive conditions, from whom LAIV therefore does not have to be withheld. In all included epidemiological studies, there was some risk of bias identified, e.g. due to residual confounding or other methodology-related sources of error. In the evaluated studies, both the vaccination of children with previous illnesses and the routine vaccination of (healthy) children frequently involve cost savings. This is especially the case if one includes indirect costs from a societal perspective. From a payer perspective, a routine vaccination of children is often regarded as a highly cost-effective intervention. However, not all of the studies arrive at consistent results. In isolated cases, relatively high levels of cost-effectiveness are reported that make it difficult to perform a conclusive assessment from an economic perspective. Based on the included studies, it is not possible to make a clear statement about the budget impact of using LAIV. None of the evaluated studies provides results for the context of the German healthcare setting. The efficacy of the vaccine, physicians' recommendations, and a potential reduction in influenza symptoms appear to play a role in the vaccination decision taken by parents/custodians on behalf of their children. Major barriers to the utilization of influenza vaccination services are a low level of perception and an underestimation of the disease risk, reservations concerning the safety and efficacy of the vaccine, and potential side effects of the vaccine. For some of the parents surveyed, the question as to whether the vaccine is administered as an injection or nasal spray might also be important.

CONCLUSION

In children aged 2 to 17 years, the use of LAIV can lead to a reduction of the number of influenza cases and the associated burden of disease. In addition, indirect preventive effects may be expected, especially among elderly age groups. Currently there are no data available for the German healthcare setting. Long-term direct and indirect effectiveness and safety should be supported by surveillance programs with a broader use of LAIV. Since there is no general model available for the German healthcare setting, statements concerning the cost-effectiveness can be made only with precaution. Beside this there is a need to conduct health eco-nomic studies to show the impact of influenza vaccination for children in Germany. Such studies should be based on a dynamic transmission model. Only these models are able to include the indirect protective effects of vaccination correctly. With regard to ethical, social and legal aspects, physicians should discuss with parents the motivations for vaccinating their children and upcoming barriers in order to achieve broader vaccination coverage. The present HTA provides an extensive basis for further scientific approaches and pending decisions relating to health policy.

Assessing the evidence: live attenuated influenza vaccine in children younger than 2 years. A systematic review

BACKGROUND

Live attenuated influenza vaccine (LAIV) is effective in children but contraindicated in children <2 years of age.

METHODS

We searched Medline, EMBASE, the Cochrane Library, Web of Science, Scopus, PsycInfo and CINAHL through February 2013 for existing systematic reviews, randomized controlled trials (RCTs) and observational studies (for safety). We included studies enrolling healthy children <2 years of age who received LAIV, compared with placebo or inactivated influenza vaccine (IIV). Data were extracted independently by 2 investigators. The relative risk (RR) was pooled across studies using the random effects model.

RESULTS

We found 7 eligible randomized controlled trials and 2 observational studies. Randomized controlled trials included 6281 children and were at low to moderate risk of bias. LAIV reduced the incidence of influenza compared with placebo (relative risk = 0.36, 95% confidence interval: 0.23-0.58, P < 0.05) with a number needed to vaccinate of 17. LAIV increased the incidence of minor side effects (fever and rhinorrhea). LAIV had a similar effect in preventing influenza (relative risk = 0.76, 95% confidence interval: 0.45-1.30, P > 0.05) compared with inactivated influenza vaccine. There was an increase of hospitalization rate (post hoc analysis) and medical attended wheezing with LAIV.

CONCLUSIONS

LAIV is highly effective in children <2 years of age compared with placebo and is as effective to inactivated influenza vaccine. The safety profile of LAIV is reasonable although evidence is sparse. LAIV may be considered as an option in this age group particularly during seasons with vaccine shortage.

Live viral vaccines in immunocompromised patients

ABSTRACT: 

Live-attenuated viral vaccines (LAV) have been used safely for several decades in healthy individuals to protect against diseases with great success. In immunocompromised hosts their use is usually not recommended. We explore the use of currently available LAV, such as live-attenuated influenza, varicella–zoster virus, measles, mumps and rubella, oral polio, rotavirus, yellow fever virus vaccines, especially in patients with cancer, solid organ or hematopoietic stem cell transplant, HIV, and with acquired or congenital immunodeficiencies. Although evidence-based recommendations cannot currently be made, it is possible that LAV will be recommended in specific, well-defined situations in these immunocompromised patients in the future.