September 5, 2015
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Flublok

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Flublok




Flublok Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 5/6/2015

Flublok (influenza vaccine) is a vaccine used to prevent seasonal influenza in adults 18 to 49 years of age. Common side effects of Flublok are injection-site reactions (pain, swelling, redness, bruising), headache, fatigue, muscle pain, fever, joint pain, nausea, and chills.

Flublok is administered by intramuscular injection through 0.5mL single dose vials. Flublok is not currently known to interact with other medications. Tell your doctor all medications you use. The safety and effectiveness of Flublok has not been established in pregnant women or nursing mothers.

Our Flublok (Influenza Vaccine) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Flublok FDA Prescribing Information: Side Effects
(Adverse Reactions)

SIDE EFFECTS

In adults 18 through 49 years of age, the most common ( ≥ 10%) injection-site reaction was pain (37%); the most common ( ≥ 10%) solicited systemic adverse reactions were headache (15%), fatigue (15%) and muscle pain (11%). (See Clinical Trials Experience)

In adults 50 through 64 years of age, the most common ( ≥ 10%) injection site reaction was pain (32%); the most common ( ≥ 10%) solicited systemic adverse reactions were headache (17%), fatigue (13%), and muscle pain (11%). (See Clinical Trials Experience)

In adults 65 years of age and older, the most common ( ≥ 10%) injection site reaction was pain (19%); the most common ( ≥ 10%) solicited systemic adverse reactions were fatigue (13%) and headache (10%). (See Clinical Trials Experience)

Clinical Trials Experience

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a vaccine cannot be directly compared to rates in the clinical studies of another vaccine and may not reflect the rates observed in clinical practice.

Flublok has been administered to and safety data collected from 2497 adults 18 through 49 years of age, 972 adults 50 through 64 years of age, and 1078 adults aged 65 years and older enrolled in five randomized, placebo- or active-controlled clinical trials. Clinical safety data for Flublok are presented from four clinical trials (Studies 1, 2, 3, and 4). Data from a placebo-controlled trial in adults 18 through 49 years of age (Study 1) are presented, followed by data pooled according to age group from Studies 2 and 4 (adults 50 through 64 years of age) and Studies 3 and 4 (adults aged 65 years and older). Reactogenicity data from a small Phase 2 trial (Study 5) in adults 18 through 49 years of age, 153 of whom received Flublok 135mcg, are not presented. However, subjects from Study 5 are included in the description of deaths and serious adverse events (SAEs). In all studies local (injection site) and systemic adverse reactions were solicited with the use of a memory aid for 7 days following vaccination, and unsolicited adverse reactions were collected for 28-30 days post-vaccination. In Studies 1- 3 and 5, SAEs were collected for 6 months post-vaccination via clinic visit or telephone follow up on Day 28, telephone follow up on Day 180, or by spontaneous reporting. Study 4 collected SAEs through 30 days following receipt of vaccine. Study 4 also actively solicited pre-specified common hypersensitivity-type reactions through 30 days following receipt of vaccine as a primary endpoint.

Study 1 included 4648 subjects 18 through 49 years of age for safety analysis, randomized to receive Flublok (n=2344) or placebo (n=2304) 2 (see Clinical Studies).

Study 2 included 602 subjects 50 through 64 years of age for safety analysis, randomized to receive Flublok (n=300) or another U.S.-licensed trivalent influenza vaccine (Fluzone, manufactured by Sanofi Pasteur, Inc.) as an active control (n=302)3 (see Clinical Studies).

Study 3 included 869 subjects aged 65 years and older for safety analysis, randomized to receive Flublok (n=436) or another U.S.-licensed trivalent influenza vaccine (Fluzone) as an active control (n=433)4 (see Clinical Studies). Study 4 included 2627 subjects aged 50 years and older for safety analysis, randomized to receive Flublok (n=1314) or another U.S.-licensed trivalent influenza vaccine (Afluria, manufactured by bioCSL Pty Ltd.) as an active control (n=1313). Among subjects 50 through 64 years of age, 672 received Flublok and 665 received Afluria. Among subjects aged 65 years and older, 642 received Flublok and 648 received Afluria (see Clinical Studies).

In a clinical trial of adults 18-49 years of age (Study 1, Table 1) the mean age of participants was 32.5 years, 59% were female, and 67% were Caucasian (see Clinical Studies).

Table 1: Frequency of Solicited Local Injection Site Reactions and Systemic Adverse Reactions within 7 Days of Administration of Flublok or Placebo in Adults 18-49 Years of Age, Study 1, Total Vaccinated Cohort1,2,3

Local Flublok
N=2272%
Placebo
N=2231%
Any Mod4 Sev4 Any Mod4 Sev4
  Pain 37 2 < 1 8 < 1 < 1
  Redness 4 < 1 < 1 2 < 1 < 1
  Swelling 3 < 1 < 1 2 < 1 < 1
  Bruising 3 < 1 < 1 3 < 1 < 1
Systemic % %
  Headache 15 3 < 1 16 3 < 1
  Fatigue 15 3 < 1 14 3 < 1
  Muscle Pain 11 2 < 1 7 < 1 < 1
  Nausea 6 1 < 1 5 1 < 1
  Joint pain 4 < 1 < 1 4 < 1 < 1
  Chills 3 < 1 < 1 3 < 1 < 1
  Fever‡ < 1 < 1 < 1 < 1 < 1 < 1
NOTE: Data based on the most severe response reported by subjects. Results ≥ 1% reported to nearest whole percent; results > 0 but < 1% reported as < 1%.
‡ Fever defined as ≥ 100.4°F (38°C). Mild ( ≥ 100.4° to < 101.1°F); Moderate ( ≥ 101.2°F to < 102.2°F); Severe ( ≥ 102.2°F)
1 Total Vaccinated Cohort is defined as all randomized subjects who received study vaccine according to the treatment actually received and who provided data.
2 Study 1 is registered as NCT00539981 under the National Clinical Trials registry.
3 Denominators for Study 1: The total number of enrolled, randomized, and vaccinated subjects was 2344 in the Flublok group and 2304 in the placebo group. For all categories except fever, the number of subjects with missing values was 72 in the Flublok group and 73 in the Placebo group so that these denominators are 2272 and 2231 respectively. For fever, 89 Flublok recipients and 104 Placebo recipients were missing data, making these denominators 2255 and 2200 respectively.
4 Moderate = had it, and it was bad enough to prevent a significant part of usual activities; Severe = had it, and it prevented most or all of normal activities, or had to see a doctor for prescription medicine.

Across three clinical trials (Studies 2 - 4, Tables 2 and 3) a total of 2050 adults age 50 years and older received Flublok and 2048 received a U.S.-licensed IIV3 comparator. The mean age of these study participants was 65 years; 56% were female and 80% were Caucasian (see Clinical Studies).

The incidence of solicited reactogenicity differed between adults 50 through 64 years of age and adults aged 65 years and older. Therefore, data from Studies 2, 3, and 4 were pooled according to age group and are presented separately (Tables 2 and 3).

Most events in both age groups were mild in severity.

Table 2: Frequency of Solicited Local Injection Site Reactions and Systemic Adverse Reactions within 7 Days of Administration of Flublok or Comparator in Adults 50-64 Years of Age, Studies 2 and 4, Total Vaccinated Cohort1,2

  Flublok
N=972
IIV32
N=967
Any Mod3 Sev3 Any Mod3 Sev3
Local %
  Pain 32 2 < 1 37 < 1 0
  Firmness/Swelling 7 2 < 1 6 1 < 1
  Redness 6 2 < 1 5 1 < 1
Systemic %
  Headache 17 4 < 1 16 3 < 1
  Fatigue 13 3 < 1 17 3 < 1
  Muscle Pain 11 2 < 1 11 2 < 1
  Joint Pain 8 2 < 1 8 2 < 1
  Nausea 6 1 0 5 < 1 < 1
  Shivers/Chills 5 1 0 4 < 1 < 1
  Fever‡ < 1 < 1 < 1 < 1 0 0
NOTE: Data based on the most severe response reported by subjects. Results ≥ 1% reported to nearest whole percent; results > 0 but < 1% reported as < 1%.
‡ Fever defined as ≥ 100.4°F (38°C). Mild ( ≥ 100.4° to < 101.1°F); Moderate ( ≥ 101.2°F to < 102.2°F); Severe ( ≥ 102.2°F) For fever, 12 Flublok recipients and 5 IIV3 recipients were missing data, making these denominators 964 and 962, respectively.
1 Total Vaccinated Cohort is defined as all randomized subjects who received study vaccine according to the treatment actually received and who provided data.
2 Pooled Data from Studies 2 and 4. For Studies 2 and 4, the U.S.-licensed IIV3 comparators were Fluzone and Afluria, respectively. Studies 2 and 4 are registered as NCT00539864 and NCT01825200, respectively, under the National Clinical Trials registry.
3 Moderate = had it, and it was bad enough to prevent a significant part of usual activities; Severe = had it, and it prevented most or all of normal activities, or had to see a doctor for prescription medicine.

Table 3: Frequency of Solicited Local Injection Site Reactions and Systemic Adverse Reactions within 7 Days of Administration of Flublok or Comparator in Adults ≥ 65 Years of Age, Studies 3 and 4, Total Vaccinated Cohort 1,2

Local Flublok
N=1078
IIV32
N=1081
Any Mod3 Sev3 Any Mod3 Sev3
%
  Pain 19 < 1 < 1 20 < 1 < 1
  Redness 7 1 < 1 7 1 1
  Firmness/Swelling 7 2 < 1 7 < 1 < 1
Systemic %
  Fatigue 13 3 < 1 15 2 < 1
  Headache 10 < 1 < 1 9 1 < 1
  Muscle Pain 8 2 < 1 8 1 < 1
  Joint Pain 6 1 < 1 6 1 < 1
  Shivers/Chills 5 < 1 < 1 5 < 1 < 1
  Nausea 4 < 1 < 1 3 < 1 < 1
  Fever‡ 3 < 1 < 1 2 0 0
NOTE: Data based on the most severe response reported by subjects. Results ≥ 1% reported to nearest whole percent; results > 0 but < 1% reported as < 1%.
‡ Fever defined as ≥ 100.4°F (38°C). Mild ( ≥ 100.4° to < 101.1°F); Moderate ( ≥ 101.2°F to < 102.2°F); Severe ( ≥ 102.2°F)
1 Total Vaccinated Cohort is defined as all randomized subjects who received study vaccine according to the treatment actually received and who provided data.
2 Pooled Data from Studies 3 and 4. For Studies 3 and 4, the U.S.-licensed IIV3 comparators were Fluzone and Afluria, respectively. Studies 3 and 4 are registered as NCT00395174 and NCT01825200, respectively, under the National Clinical Trials registry.
3 Moderate = had it, and it was bad enough to prevent a significant part of usual activities; Severe = had it, and it prevented most or all of normal activities, or had to see a doctor for prescription medicine.

Among adults 18-49 years of age (Studies 1 and 5 pooled), through 6 months post-vaccination, two deaths were reported, one in a Flublok recipient and one in a placebo recipient. Both deaths occurred more than 28 days following vaccination and neither was considered vaccine-related. SAEs were reported by 32 Flublok recipients and 35 placebo recipients. One SAE in a Flublok recipient was assessed as possibly related to the vaccine: pleuropericarditis with effusions requiring hospitalization and drainage. No specific cause was identified. The patient recovered.

Among adults 50-64 years of age (Studies 2 and 4 pooled), through up to 6 months post-vaccination, there were no deaths; SAEs were reported by 10 subjects, 6 Flublok recipients and 4 IIV3 recipients. One of the SAEs, vasovagal syncope following injection of Flublok, was considered related to study vaccine. Among adults 65 years of age and older (Studies 3 and 4 pooled), through up to 6 months post-vaccination, there were 4 deaths, 2 in Flublok recipients and 2 in IIV3 recipients. None were considered related to the study vaccines. SAEs were reported from 80 subjects, 37 Flublok recipients, 43 in IIV3 recipients. None were considered related to the study vaccines.

In Study 1(adults 18-49 years of age), the most frequent unsolicited adverse events, occurring in 1%-2% of subjects, were nasopharyngitis, upper respiratory infection, headache, cough, nasal congestion, pharyngolaryngeal pain, and rhinorrhea.

Among adults 50-64 years of age (Studies 2 and 4 pooled), the most frequent unsolicited adverse events, occurring in 1% of subjects, were diarrhea and cough. Among adults ≥ 65 years of age (Studies 3 and 4 pooled), the most frequent unsolicited adverse events, occurring in 1% of subjects, were nasopharyngitis and cough.

Among adults 50 years of age and older (Study 4) for whom the incidence of rash, urticaria, swelling, nonpitting edema, or other potential hypersensitivity reactions were actively solicited for 30 days following vaccination, a total of 2.4% of Flublok recipients and 1.6% of IIV3 recipients reported such events over the 30 day follow-up period. A total of 1.9% and 0.9% of Flublok and IIV3 recipients, respectively, reported these events in the 7 days following vaccination. Of these solicited events, rash was most frequently reported (Flublok 1.3%, IIV3 0.8%) over the 30 day follow-up period.

Postmarketing Experience

The following events have been spontaneously reported during post approval use of Flublok. They are described because of the strength of the causal relationship to Flublok and their potential seriousness. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to vaccine exposure.

Immune system disorders: anaphylaxis, anaphylactoid reactions, allergic reactions, and other forms of hypersensitivity.

Read the entire FDA prescribing information for Flublok (Influenza Vaccine for Intramuscular Injection)

Report Problems to the Food and Drug Administration

 

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.


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