Fever following administration of two inactivated influenza vaccines—A survey of parents of New Zealand infants and children 5 years of age and under

Assessment of an optimized manufacturing process for inactivated quadrivalent influenza vaccine: a phase III, randomized, double-blind, safety and immunogenicity study in children and adults

BACKGROUND

GSK has modified the licensed monovalent bulk manufacturing process for its split-virion inactivated quadrivalent influenza vaccine (IIV4) to harmonize the process among different strains, resulting in an increased number of finished vaccine doses, while compensating for the change from inactivated trivalent influenza vaccine (IIV3) to IIV4. To confirm the manufacturing changes do not alter the profile of the vaccine, a clinical trial was conducted to compare IIV4 made by the currently licensed process with a vaccine made by the new (investigational) process (IIV4-I). The main objectives were to compare the reactogenicity and safety of IIV4-I versus IIV4 in all age groups, and to demonstrate the non-inferiority of the hemagglutination-inhibition (HI) antibody responses based on the geometric mean titer ratio of IIV4-I versus IIV4 in children.

METHODS

The Phase III, randomized, double-blind, multinational study included three cohorts: adults (18-49 years; N = 120), children (3-17 years; N = 821), and infants (6-35 months; N = 940). Eligible subjects in each cohort were randomized 1:1 to receive IIV4-I or IIV4. Both vaccines contained 15 μg of hemagglutinin antigen for each of the four seasonal virus strains. Adults and vaccine-primed children received one dose of vaccine, and vaccine-unprimed children received two doses of vaccine 28 days apart. All children aged ≥9 years were considered to be vaccine-primed and received one dose of vaccine.

RESULTS

The primary immunogenicity objective of the study was met in demonstrating immunogenic non-inferiority of IIV4-I versus IIV4 in children. The IIV4-I was immunogenic against all four vaccine strains in each age cohort. The reactogenicity and safety profile of IIV4-I was similar to IIV4 in each age cohort, and there was no increase in the relative risk of fever (≥38 °C) with IIV4-I versus IIV4 within the 7-day post-vaccination period in infants (1.06; 95% Confidence Interval: 0.75, 1.50; p = 0.786).

CONCLUSIONS

The study demonstrated that in adults, children, and infants, the IIV4-I made using an investigational manufacturing process was immunogenic with a reactogenicity and safety profile that was similar to licensed IIV4. These results support that the investigational process used to manufacture IIV4-I is suitable to replace the current licensed process.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02207413 ; trial registration date: August 4, 2014.

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.

Rapid online identification of adverse events after influenza immunization in children by PCIRN's National Ambulatory Network

BACKGROUND

A National Ambulatory Network was created in 2009 to rapidly assess the safety of influenza vaccines. In 2012, the network was expanded to monitor the safety of live attenuated influenza vaccine and trivalent inactivated influenza vaccine in children.

METHODS

We used an online survey administered 7 days after influenza immunization to track new or exacerbated health problems that required medical consultation or prevented daily activities. Parents of immunized children completed the survey. Reported adverse events were followed up by telephone within 48 hours of the online report. A sample of nonresponders was contacted by telephone to ensure the online responder group was representative. Event rates after the 2 influenza vaccines were compared.

RESULTS

A total of 1230 parents completed an online or telephone survey, for a participation rate of 83%: 72% responded online and an additional 11% were reached by telephone. The rate of severe events in children immunized with an influenza vaccine was 4.7% (3.5-5.9%). The frequency and types of events reported were similar between online and telephone reports. Reported rates of severe events were similar after trivalent inactivated influenza or live attenuated influenza vaccine (4.0% vs. 5.1%, respectively). The online survey was easy to access and understand. Most respondents (94%) would participate next year.

CONCLUSIONS

The rate and type of adverse events after immunization with trivalent inactivated influenza versus live attenuated influenza vaccine were similar and did not vary by reporting process (online vs. telephone). The electronic surveillance methodology provided rapid vaccine safety data in children. The electronic survey methodology was acceptable and feasible.

General practice encounters following seasonal influenza vaccination as a proxy measure of early-onset adverse events

BACKGROUND

In 2010, use of seasonal trivalent influenza vaccine (TIV) in children <5 years of age was suspended in Australia following reports of vaccine-related febrile convulsions. We investigated the utility of data on primary care [general practice (GP)] consultations for any reason within three days of receipt of influenza vaccine as recorded on the Australian Childhood Immunisation Register (ACIR) as a means of signal detection.

METHODS

Data on GP consultations were obtained from Medicare Australia (Australian Government Department of Human Services) for children recorded on the ACIR as receiving either TIV or monovalent influenza vaccine. Rates of GP consultation by day following ACIR-recorded receipt of influenza vaccine were compared by year (2008-2010), vaccine type, age and region.

RESULTS

In 2010, GP encounter rates on the day after receipt of the TIV manufactured by bioCSL (formerly CSL Biotherapies (Fluvax(®)) were significantly higher than both bioCSL TIVs in the previous two years [rate ratio (RR) 1.9; 95% CI: 1.7-2.2] and Sanofi Pasteur TIV, Vaxigrip(®) [RR 1.6, 95% CI 1.4-1.7] in 2009-2010. Encounter rates were also higher than for CSL Monovalent influenza vaccine, Panvax(®) [RR 1.9, 95% CI 1.7-2.2] in 2009-2010. These findings were robust to adjustment for age group (≤ 2, >2 years) and region (Western Australia vs other Australian states/territories).

CONCLUSIONS

A primary care consultation on the day after vaccine receipt is a reasonable proxy for early reactogenicity and has potential for use in various settings.

The risk of fever following one dose of trivalent inactivated influenza vaccine in children aged ≥6 months to <36 months: a comparison of published and unpublished studies

There are limited summary data published on the risk of fever and febrile seizures in children following influenza vaccination. We performed a review of the risk of fever and febrile seizures following receipt of trivalent inactivated influenza vaccine (TIV) in children aged ≥6 months to <36 months, searching PubMED and Google Scholar for English language articles from 2000 onwards, and initiated or ongoing unpublished studies since September 2007 using Clinicaltrials.gov. Exclusions included other vaccine co-administration, missing ages or participant numbers, or unmeasured fever. We reviewed articles and collated results using a standard data extraction template. We identified a total of 909 published papers and unpublished trials from a search conducted on 23 January 2013, 669 from Google Scholar, 114 from PubMed and 126 from the Clinicaltrials.gov online database. After excluding 890 published papers or unpublished trials, 5 published papers and 14 unpublished trials were included in this review. Extracted data on number of events, children at risk and time of follow-up were converted to the risk of fever, which was averaged per week of follow-up (referred to as 'averaged weekly risk'). Following one dose of TIV, the median averaged weekly risk of any fever (≥37.5°C) was 26.0% (range 10.3-70.0%) in unpublished trials compared to 8.2% (range 5.3-28.3%) in published papers (p=0.04). The median averaged weekly risk of severe fever (≥39.0°C) was 3.2% (range 0-10.0%) and 2.0% (range 0.6-17.0%), respectively (p=0.91). Variation in the reporting of fever by participant age groups, time since vaccination and the definition or measurement of fever resulted in a wide range of risk estimates. Reporting of febrile reactions should be standardised to allow comparison between manufacturers and influenza seasons.

The immunogenicity and safety of a single 0.5 mL dose of virosomal subunit influenza vaccine administered to unprimed children aged ≥6 to <36 months: data from a randomized, Phase III study

This study evaluated the immunogenicity, safety and tolerability of a single 0.5 mL dose of the seasonal virosomal subunit influenza vaccine (Inflexal V, Crucell, Switzerland) in 205 healthy, unprimed children aged at least 6 to <36 months, evaluated at four weeks post-vaccination and seven months from baseline. Of the enrolled children, 102 received one single 0.5 mL dose and 103 received the standard two 0.25 mL doses given four weeks apart. Both treatments evoked an immune response that satisfied the EMA/CHMP criteria for yearly vaccine licensing for all three vaccine strains. Exploratory analyses revealed no differences between the groups at four weeks post-vaccination. Furthermore, immunogenicity was maintained seven months after the first vaccination after both the 0.5 mL and standard two 0.25 mL doses. Adverse events were comparable between groups and were as expected according to the safety profile of the vaccine; overall, the vaccine was well tolerated. Our results show that a single 0.5 mL dose effectively and safely provided long-term immunogenicity to all three influenza strains in unprimed children aged at least 6 to <36 months.

Febrile events including convulsions following the administration of four brands of 2010 and 2011 inactivated seasonal influenza vaccine in NZ infants and children: the importance of routine active safety surveillance

OBJECTIVE

To evaluate and compare rates of febrile events, including febrile convulsion, following immunisation with four brands of inactivated 2010 and 2011 influenza vaccine in NZ infants and children.

DESIGN

Retrospective telephone surveys of parents of infants and children who received at least one dose of the vaccines of interest.

SETTING

184 NZ General Practices who received the vaccines of interest.

PARTICIPANTS

Recipients of 4088 doses of trivalent inactivated vaccines Fluvax(®), Vaxigrip(®), Influvac(®) and Fluarix(®) and/or monovalent Celvapan. Vaccinees were identified via the electronic Practice Management System and contacted consecutively.

MAIN OUTCOME MEASURES

Primary outcome was febrile convulsive seizure. Secondary outcomes were presence of fever plus other organ system specific symptoms.

RESULTS

The parental response rate was 99%. Of 4088 doses given, 865 were Fluvax(®), 2571 Vaxigrip(®), 204 Influvac(®), 438 Fluarix(®) and 10 Celvapan. Three febrile convulsions followed Fluvax(®), a rate of 35 per 10,000 doses. No convulsions occurred following any dose of the other vaccines. There were nine febrile events that included rigors, all following Fluvax(®). Fever occurred significantly more frequently following administration of Fluvax(®) compared with the other brands of vaccines (p<0.0001) and Fluvax recipients were more likely to seek medical attention. Influvac(®) also had higher rates of febrile reactions (OR 0.54, 0.36-0.81) than the other two brands Vaxigrip(®) (OR 0.21, 0.16-0.27) and Fluarix(®) (OR 0.10, 0.05-0.20). After multivariable analysis vaccine, European ethnicity and second dose of vaccine were significantly associated with reporting of fever within 24h of vaccination.

CONCLUSIONS

Influenza vaccines have different rates of reactogenicity in children which varies between ethnic groups. High rates of febrile convulsions and reactions in children receiving Fluvax(®) and to a lesser extent the higher fever rates in those receiving Influvac(®) compared with the other two brands of influenza vaccines in this study suggests that reactogenicity profiles need to be considered prior to national policy advice each season. The risk-benefit profile in children might not be equally favourable for all licensed paediatric influenza vaccines. More attention needs to be given to comparative research for all trivalent seasonal vaccines, and with all strain changes.

Parental views on vaccine safety and future vaccinations of children who experienced an adverse event following routine or seasonal influenza vaccination in 2010

To assess parental vaccine safety views and future vaccination decisions after an adverse event following immunization (AEFI) experienced by their child. A cross-sectional telephone survey was conducted of parents of children aged 0-7 y, identified in AEFI reports submitted to the South Australian Immunization Section, Department Health. The reports included childhood National Immunization Program (NIP), seasonal or pandemic influenza vaccines. Interviews were conducted following a national suspension of the 2010 seasonal trivalent influenza (STIV) vaccine. Parental attitudes toward vaccine safety, reasons for reporting the AEFI and impact on future vaccination intent were assessed. Of 179 parents interviewed, 88% were confident in the safety of vaccines in general. Parents reporting an AEFI to the STIV were more likely to state the event had influenced future vaccination decisions than the NIP vaccine reporters (65% vs 14%, p < 0.001), with 63% stating refusal or hesitance to re-vaccinate their children against influenza. Media reports of the 2010 STIV program suspension was the most common reason for reporting an AEFI for parents of children who received an influenza vaccination. The AEFI experience did not impact on parental decision to continue with routine childhood NIP schedules, regardless of whether children received influenza or NIP vaccines. In contrast, most parents whose child experienced an AEFI to the 2010 STIV stated decreased confidence in the safety of influenza vaccines, which is likely to have impacted on the uptake of seasonal influenza vaccination in 2011. Addressing influenza vaccine safety concerns to promote influenza vaccination in the community is required.

Influenza vaccine safety in children less than 5 years old: the 2010 and 2011 experience in Australia

In August 2010, the United States Advisory Committee on Immunization Practices recommended that the 2010-2011 CSL seasonal vaccine (Afluria) not be administered to children 6 months to 8 years of age because of the risk of febrile convulsion after immunization. This study reports a low rate (6%-7%) of fever after immunization with 2 non-CSL brands of 2011 seasonal influenza vaccine in Australian children <5 years of age. These data are reassuring for parents and healthcare workers regarding 2011 influenza vaccination in the northern hemisphere.