With influenza B making a late-season rise, health officials are warning that B viruses may cause a second wave of flu this season, while the FDA is backing some alternatives to egg-based flu vaccines.
The number of states reporting widespread flu activity continues to drop, according to the Centers for Disease Control and Prevention (CDC). According to the new FluView report for week 11 ending March 17, 2018, 17 states reported widespread flu activity, down from the previous week’s total of 26 states plus Puerto Rico. The proportion of outpatient visits for influenza-like illness also declined, going from 3.3% in week 10 to 2.7% in week 11, although the percentage remains above the national baseline of 2.2%. Health officials have also reported 5 new influenza-associated pediatric deaths, bringing the total number of pediatric flu deaths in the United States to 133 for the 2017-2018 flu season.
With the late season surge of influenza B virus, the CDC has reported that B viruses made up more than 57% of flu-positive respiratory specimens collected by public health and clinical laboratories. During week 1, influenza A viruses accounted for more than 83% of flu-positive respiratory specimens. A rise in influenza B is common late in a flu season and the CDC is warning that it’s causing a second wave of flu this season, which may lead to some individuals falling ill with the flu for a second time in one season. Because this season’s flu vaccine has been about 42% effective against influenza B, the CDC continues to recommend getting a flu shot for anyone who hasn’t yet.
On the heels of recent research linking egg-based flu vaccine production to the low effectiveness of the flu shot, health officials have indicated that alternatives to egg-based vaccines may already be proving more effective. US Food and Drug Administration commissioner Scott Gottlieb, MD, recently gave an oral testimony before the US House Committee on Energy and Commerce Subcommittee on Oversight and Investigations on the current flu season, and new data showing that cell-based and recombinant vaccines have been more efficacious this flu season. This season, the flu vaccine has been about 36% effective overall at protecting against the flu overall, and only 25% effective against the influenza A (H3N2) strain that predominated most of the season.
“The data aren’t final yet, but I’m comfortable saying that I think it’s going to be about 20 percent improved efficacy for the cell-based vaccine relative to the egg-based vaccines,” Dr. Gottlieb said, however, in a recent statement.
While much recent research has focused on the development of a universal flu vaccine that can offer protection from the flu for several seasons, it will be years until such a vaccine is available, and so, Dr. Gottlieb emphasized the need to improve the production of existing vaccines.
“As we consider greater investment in alternative vaccine development processes, it’s important to note, however, that there are also challenges with these newer cell-based approaches,” said Dr. Gottlieb in his statement to Congress. “To help address these challenges, the FDA is working to help develop more effective cell lines that can be better scaled through continuous manufacturing. We’re also looking at how we develop a more robust recombinant vaccine manufacturing process to increase yield while reducing cost.”