Evaluating the Safety and Efficacy of Anti-Influenza Intravenous Hyperimmune Immunoglobulin (IVIG) in Adults Hospitalized With Influenza

Influenza (the flu) is a common illness that usually occurs in autumn and winter. The flu is usually mild, but can cause serious illness or death. The purpose of this study is to test the safety and effectiveness of an antibody against the flu (called intravenous hyperimmune immunoglobulin or IVIG) in people who are hospitalized for severe flu.

Influenza is responsible for thousands of hospitalizations and deaths each year in the United States and worldwide. One possible new treatment for the flu involves the use of IVIG, a blood product containing antibodies from people who have recovered from the flu or who have had a flu shot. The purpose of this study is to evaluate whether IVIG can reduce the severity and duration of flu in people who are hospitalized with the flu.

The study will enroll participants 18 years and older who are hospitalized with the flu. The study will enroll participants over one or more flu seasons. Regardless of the date of enrollment, each participant will be in the study for about 28 days.

At study entry (Day 0), participants will be randomly assigned to one of two groups (Arms A and B). Participants in both groups will receive standard of care (SOC) treatment for the flu, but those in Arm A will also receive one dose of IVIG and those in Arm B will receive a placebo for IVIG. Both IVIG and placebo will be given intravenously over at least 2 hours.

On Day 0, before receiving IVIG or placebo, participants will undergo a symptoms assessment, blood collection, and a nasopharyngeal (NP) swab to collect a sample of secretions from the nose and throat.

Additional study visits will occur on Days 1, 2, 3, 7, 14, and 28. Depending on the visit, participants may take part in the same study procedures that took place on Day 0. On Days 2, 14, and 28, visits for participants who are no longer hospitalized may be conducted over the phone.

Eligibility Criteria:
Inclusion Criteria:

* Signed informed consent
* Locally determined positive influenza test (by polymerase chain reaction \[PCR\] or other nucleic acid test, or by rapid antigen \[Ag\]) from a specimen obtained within 2 days prior to randomization
* Onset of illness no more than 7 days before randomization, defined as when the participant first experienced at least one respiratory symptom or fever
* Hospitalized (or in observation unit) for influenza, with anticipated hospitalization for more than 24 hours. Criteria for hospitalization will be up to the individual treating clinician.
* For women of child-bearing potential: willingness to abstain from sexual intercourse or use at least one form of hormonal or barrier contraception through Day 28 of the study
* Willingness to have blood and respiratory samples obtained and stored
* NEW score greater than or equal to 2 at screening (see the protocol for more information on this criterion)

Exclusion Criteria:

* Women who are pregnant or breast-feeding
* Strong clinical evidence (in the judgment of the site investigator) that the etiology of illness is primarily bacterial in origin
* Prior treatment with any investigational drug therapy within 30 days prior to screening
* History of allergic reaction to blood or plasma products (as judged by the site investigator)
* Known immunoglobulin A (IgA) deficiency
* A pre-existing condition or use of a medication that, in the opinion of the site investigator, may place the participant at a substantially increased risk of thrombosis (e.g., cryoglobulinemia, severe refractory hypertriglyceridemia, or clinically significant monoclonal gammopathy)
* Presence of any pre-existing illness that, in the opinion of the site investigator, would place the participant at an unreasonably increased risk through participation in this study
* Participants who, in the judgment of the site investigator, will be unlikely to comply with the requirements of this protocol
* Medical conditions for which receipt of a 500 mL volume of intravenous fluid may be dangerous to the participant (e.g., decompensated congestive heart failure)
* Receiving extracorporeal membrane oxygenation (ECMO)
* Suspicion that infection is due to an influenza strain or subtype other than A(H1N1)pdm09, H3N2, or influenza B (e.g., H5N1, H7N9)