Hemispherx Biopharma Inc (NYSE American: HEB) has updated the US Food and Drug Administration (FDA) on its Phase I/II trial of intranasal Ampligen in combination with FluMist influenza vaccine, the company reported on Monday.

The two-stage, randomised, double-blinded, placebo-controlled clinical trial assessed the immunogenicity and safety of intranasal FluMist administered sequentially with intranasal Ampligen.

In a clinical study report, Hemispherx said there was no evidence of any increase in adverse effects related to higher dosage levels of Ampligen or to the continued administration of Ampligen during the second and third dual vaccinations. The intranasal use of Ampligen and FluMist was generally well-tolerated and generated antibodies against influenza subtypes not present in the seasonal vaccine.

According to company, pre-clinical studies of Ampligen in combination with seasonal influenza vaccines indicate that the intranasal combination could be "highly effective" against both seasonal and avian influenza A viruses (H5N1) and 3 H5N1 clades.

Moreover, in both preclinical and clinical studies, the intranasal combination of seasonal vaccine and Ampligen was observed to generate cross reactive antibodies, which could extend or preserve vaccine efficacy as viruses mutate.