CDC Estimate of Seasonal Flu-Related Deaths Increases Worldwide

A new robust, multinational survey released by the Centers for Disease Control and Prevention (CDC) yesterday reported some unsettling news: the estimated number of annual respiratory deaths caused by seasonal flu has increased on a global scale.

According to the new estimates, between 291,000 and 646,000 individuals worldwide die from flu-related illness. These numbers are an increase from previous estimates of 250,000 to 500,000 deaths attributed to the virus.

The new estimates are based on the results of a study which pulled data from a larger and more diverse group of countries than previous estimates. According to the collaborative study, published in The Lancet, the data were from 47 countries in total. Thirty-three of the 47 countries had death records and surveillance information available for at least 4 years between 1999 and 2015. Investigators calculated the annual number of seasonal influenza-related deaths for those 33 countries. “Statistical modeling with those results was used to generate an estimate of the number of flu-associated respiratory deaths for 185 countries across the world,” according to the official press release. They took data from the other 14 countries to validate the estimates yielded by the statistical models.

“These findings remind us of the seriousness of flu and that flu prevention should really be a global priority,” study co-author Joe Bresee, MD, associate director for global health in the CDC’s Influenza Division said in the official press release.

The strongest preventive action that individuals can take to protect themselves against the flu? Vaccination.

Unfortunately, there are many common misconceptions about the flu vaccine that have some individuals on the fence when it comes to receiving a flu shot. One false misconception is that an individual can get flu from the vaccine. “That’s a myth; there’s no truth to it,” William Schaffner, MD, medical director of the National Foundation for Infectious Diseases, told Contagion ^® in a recent interview. “It may well be that somebody got vaccinated on Monday and on Wednesday they got a cold, and what they’ll do is attribute that cold to having received the vaccine, but there’s no connection.”

The idea that the vaccine does not provide adequate protection against the virus has also been plastered across several headlines. “We all wished it would work better, but it’s a pretty darn good vaccine and it’s the best vaccine we have right now,” Dr. Schaffner stressed. “It always prevents many, many infections. And remember, if it doesn’t prevent the infection completely, it will modify the infection; it will make it milder, makes it less likely if you get flu that you have to go to the hospital, be admitted to the intensive care unit, or die.” Vaccination is even more important for individuals at increased risk of infection such as women who are pregnant, young children, and older adults.

For the Lancet study, the investigators calculated age-specific mortality rates. They found that older adults, particularly those aged 75 and older had the greatest mortality burden. In addition, the investigators calculated region-specific mortality rates, and, perhaps not so surprisingly, the world’s poorest regions bore the greatest flu mortality burden. Thus, adults 75 or older living in sub-Saharan African countries had the highest rates of flu-associated death. Eastern Mediterranean and Southeast Asian countries also proved to have high flu-related death rates in this population.

Although recommendations are in place, the problem is that more often than not, underdeveloped countries are unable to produce and distribute seasonal vaccines, and many lack vaccination programs.

The CDC is working hard to address this global problem by strengthening global flu surveillance. Already, the CDC has worked with over 60 countries to strengthen their surveillance and laboratory capacity to help inform practitioners which strains should be included in the seasonal flu vaccines developed each year.

“This work adds to a growing global understanding of the burden of influenza and populations at highest risk,” lead author of the study Danielle Iuliano, CDC researcher, said in the press release.

Researchers are still working on calculating non-respiratory causes of flu-related deaths.