Influvac, a trivalent inactivated subunit influenza vaccine

Safety and immunogenicity of a novel quadrivalent subunit influenza vaccine in animal models

Background: Compared with trivalent influenza vaccines, quadrivalent influenza vaccines are expected to provide wider protection against influenza B virus infections. We developed a novel quadrivalent subunit influenza vaccine which was distinct from the influenza vaccines available on the market in production process. In this research, we evaluated the safety and immunogenicity of the quadrivalent subunit influenza vaccine in animal models. Methods: In toxicity assessment, 40 SD rats were randomly assigned to be intramuscularly injected with 1.0 ml of the tested vaccine (33 μg/ml) or 0.9% sodium chloride solution. In irritation assessment, eight rabbits were randomly assigned to receive 0.5 ml of tested vaccine or phosphate buffer solution intramuscularly. Thirty-two guinea pigs were randomly assigned to be intramuscularly injected with high-dose tested vaccine (0.5 ml), low-dose tested vaccine (0.05 ml), ovalbumin, or 0.9% sodium chloride solution, respectively, for sensitization assessment. In immunogenicity assessment, 50 BALB/c mice were equally randomized to receive one dose of tested vaccine, two doses of tested vaccine with an interval of 14 days, 0.5 ml of trivalent subunit influenza vaccine, 0.5 ml of monovalent subunit influenza vaccine, or 0.5 ml of phosphate buffer solution. Orbital blood was collected before and 28 and 42 days after administration of the injections for detecting influenza antibody titers. Results: No abnormal toxicity and irritation in rats and rabbits showed in the gross autopsy and histopathological examinations. The results of sensitization in guinea pigs indicated that no obvious allergic symptoms observed in the high-dose and low-dose vaccine groups within 30 min after twice provocations, and the result of sensitization evaluation was negative. Vaccine induced significant immune responses in mice with 100% seroconversion rates at 28 and 42 days after the first dose. The geometric mean titers (GMTs) of hemagglutination inhibition (HI) antibodies at day 28 in one-dose quadri-vaccine and two-dose quadri-vaccine groups were comparable to those in the tri-vaccine or mono-vaccine groups for shared influenza strains. However, the GMTs of HI antibodies against H1N1 (P = 0.025) and BV (P = 0.049) at day 42 in one-dose quadri-vaccine group were significantly lower than those in the tri-vaccine or mono-vaccine groups. The GMTs of HI antibodies against H1N1, H3N1, BY, and BV at day 28 and day 42 were comparable between one-dose quadri-vaccine and two-dose quadri-vaccine groups. Conclusions: The quadrivalent subunit influenza vaccine was safe and immunogenic in animal models. One dose of the vaccine could elicit a satisfactory antibody response in mice.

MF59-adjuvanted seasonal trivalent inactivated influenza vaccine: Safety and immunogenicity in young children at risk of influenza complications

OBJECTIVE

To assess the safety and immunogenicity of the MF59-adjuvanted seasonal trivalent inactivated influenza vaccine (aIIV3; Fluad) in children aged 6 months through 5 years who are at risk of influenza complications.

METHODS

A retrospective analysis was performed to examine unsolicited adverse events (AEs) in an integrated dataset from six randomized clinical studies that compared aIIV3 with non-adjuvanted inactivated influenza vaccines (IIV3). The integrated safety set comprised 10 784 children, of whom 373 (3%) were at risk of influenza complications.

RESULTS

The at-risk safety population comprised 373 children aged 6 months through 5 years: 179 received aIIV3 and 194 received non-adjuvanted IIV3 (128 subjects received a licensed IIV3). The most important risk factors were respiratory system illnesses (62-70%) and infectious and parasitic diseases (33-39%). During the treatment period, unsolicited AEs occurred in 54% of at-risk children and 55% of healthy children who received aIIV3; of those receiving licensed IIV3, 59% of at-risk and 62% of healthy subjects reported an unsolicited AE. The most common AEs were infections, including upper respiratory tract infection. Serious AEs (SAEs) were reported in <10% of at-risk subjects, and no vaccine-related SAEs were observed. In the immunogenicity subset (involving 103 participants from one study), geometric mean titers (GMTs) were approximately 2- to 3-fold higher with aIIV3 than with IIV3 for all three homologous strains (A/H1N1, A/H3N2, and B). Seroconversion rates were high for both aIIV3 (79-96%) and IIV3 (83-89%).

CONCLUSIONS

In young children at risk of influenza complications, aIIV3 was well-tolerated and had a safety profile that was generally similar to that of non-adjuvanted IIV3. Similar to the not-at-risk population, the immune response in at-risk subjects receiving aIIV3 was increased over those receiving IIV3, suggesting aIIV3 is a valuable option in young children at risk of influenza complications.

Viral Sepsis in Children

Sepsis in children is typically presumed to be bacterial in origin until proven otherwise, but frequently bacterial cultures ultimately return negative. Although viruses may be important causative agents of culture-negative sepsis worldwide, the incidence, disease burden and mortality of viral-induced sepsis is poorly elucidated. Consideration of viral sepsis is critical as its recognition carries implications on appropriate use of antibacterial agents, infection control measures, and, in some cases, specific, time-sensitive antiviral therapies. This review outlines our current understanding of viral sepsis in children and addresses its epidemiology and pathophysiology, including pathogen-host interaction during active infection. Clinical manifestation, diagnostic testing, and management options unique to viral infections will be outlined.