The mortality associated with influenza deaths is vastly under-estimated

Health 15 December, 2017


Published the 15.12.2017 at 17h19


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Estimates of mortality associated with influenza are important for health policies national and international. Estimates older than 250 000 to 500 000 annual deaths related to influenza are very much outdated.
A study published in the Lancet updates the estimated number of annual deaths from causes respiratory flu-associated and the least we can say is that it is widely under-estimated.
The rate of deaths considered related to the seasonal influenza would currently be 291 243 645 832 deaths, respiratory related (4.0 to 8.8 per 100 000 people) each year.

A much more accurate assessment

Researchers have estimated the rate of excess mortality from respiratory influenza-associated specific to each country in 33 countries in models using time-series data based on records of deaths and of the data of influenza surveillance from 1999 to 2015.
This analysis was performed for three age groups (under 65, 65 to 74 years, and 75 years and more), as well as children under 5 years of age, using mortality rates of respiratory infections to the WHO.

An excess mortality related to the age

The countries where it has been possible to identify a rate of excess mortality from respiratory accounted for 57% of the world population. The rate of excess mortality from respiratory annual associated with influenza estimated in the range of 0.1 to 6.4 per 100 000 persons under the age of 65 years, 2.9-44.0 per 100 000 persons 65 to 74 years of age, and 17.9 to 223,5 per 100 000 people over 75 years of age.
In 92 countries, estimates of flu-related deaths in children under 5 years of age are 9243-105 690 deaths respiratory flu each year.

Excess mortality related to the country

The highest mortality rates are found in sub-saharan Africa (2.8 to 5.5 per 100 000 individuals), in South-East Asia (3.5 to 2.6 per 100 000 individuals) and among those aged 75 years or older ( 51,3-for 99.4 per 100 000 person).

The seasonal flu

Influenza is an acute respiratory infection caused by a respiratory virus. It is very contagious and occurs therefore in the course “epidemics” that affect a large number of people every winter in France and in the northern hemisphere (and summer in the southern hemisphere). It can last until the spring and may sometimes co-exist in January February with an epidemic of gastro-enteritis.
Often considered benign, the influenza, however, can lead to serious complications, mainly pulmonary in the fragile and decompensation of pre-existing illnesses in certain populations at risk.

Frequent complications

In adults and young children in good health, the healing is usually done in a week, but fatigue and dry cough may often persist for three or four weeks.
In vulnerable people (elderly, immunocompromised, pregnant women…) or having a chronic disease (diabetes, heart failure, respiratory or renal…), the flu is less well supported, it is often more severe and complications can occur : bacterial lung infection is serious (or ” pneumonia “) or a decompensation or worsening of the underlying chronic disease (diabetes, respiratory failure, cardiac or renal disease, cystic fibrosis, etc.).
Infants, particularly those less than six months, also have an increased risk of complications. However, as they cannot yet receive the vaccine, they should be protected by their loved ones thanks to ” gestures barrier “.

These estimates of respiratory mortality associated with influenza in the world are therefore higher than the estimates known, suggesting that the severity of the flu and its complications could have been underestimated. The contribution of causes of non-respiratory deaths to the overall mortality associated with the influenza should also be considered.