CDC Estimates 7 Million Influenza Infections So Far in 2018-2019 Season

Influenza activity remained elevated in all 10 regions of the United States during week 1 of 2019, which concluded on January 5, according to the US Centers for Disease Control and Prevention’s (CDC) weekly FluView report. Widespread influenza activity was reported in 30 states and Puerto Rico, while 17 states reported regional activity, and 2 states reported local activity. Of the 4460 respiratory specimens that tested positive for influenza in public health and clinical laboratories around the country, 97.1% were identified as influenza A and 2.5% were influenza B. Influenza A (H1N1) pdm09 is currently the most predominant subtype.

On January 11 the CDC released its first in-season estimates of flu illnesses, medical visits, and hospitalizations in the United States for the 2018-2019 flu season. From October 1, 2018, through January 5, 2019, between 6 and 7 million individuals in the US have become sick with the flu, up to half of whom have sought medical care. Between 69,000 and 84,000 individuals have been hospitalized due to influenza. The CDC derived these figures using a mathematical model with calculations based on adjusted rates of laboratory-confirmed, influenza-associated hospitalizations collected through its surveillance network covering about 8.5% of the US population.

The report also notes that the CDC will release an estimate on flu-related deaths this season once there is sufficient data to provide a more precise estimate, though flu deaths continue to mount across the country.

The California Department of Public Health has issued an alert to state residents about a spike in influenza activity, along with a reminder to get vaccinated, following news of the death of a 4-year-old child in Riverside County who tested positive for influenza. This marks the third pediatric influenza-related death in 2019.

A recent study led by Georgia Tech investigators and published in the journal PLOS One examined how influenza vaccine allocation decisions can reduce the burden of a serious flu pandemic when vaccine supply is limited. According to the study, too often there are areas that end the influenza season with excess vaccine inventory while other areas cannot meet local demand. With few states collecting detailed information on the number of vaccines administered in each location, the result is a lack of visibility in the vaccine supply chain.

For the study, investigators compared the current population-based approach—in which vaccine distributors restock areas in proportion with population—with a population and inventory-based approach. The inventory-based approach included a proposed allocation method calculated to save more lives in a pandemic or intense influenza outbreak in which there are depleted vaccine supplies. The new approach also targets the problem of leftover vaccine inventory, which can leave states with extra cost burdens for storage and disposal.

The study found that with the population and inventory-based approach to influenza vaccine distribution, the cumulative percentage of the population infected during the epidemic fell from 23.4% to 22.4%, leftover influenza vaccine doses fell by 667,000, and the percent of the population that got vaccinated stayed the same or increased. With improved visibility in influenza vaccine inventory, states could design policies or information campaigns for areas with low uptake rates, say the authors.

“The data would tell you where you need continued education about the importance of vaccination, and some of the money saved from unnecessary resupplying could be invested in public health campaigns,” Julie L. Swann, PhD, department head and A. Doug Allison Distinguished Professor of the Fitts Department of Industrial and Systems Engineering at North Carolina State University and study co-author, said in a recent statement. “Surprisingly few states have systems in place that tell them how much vaccine has been administered where and how much is still left in inventory at provider locations.”