[Source: US National Library of Medicine, full text: (LINK). Abstract, edited.]
PLoS One. 2013 May 22;8(5):e64198. Print 2013.
Influenza Mortality in the United States, 2009 Pandemic: Burden, Timing and Age Distribution.
Nguyen AM, Noymer A.
Source: Palomar Health, Escondido, California, United States of America.
In April 2009, the most recent pandemic of influenza A began. We present the first estimates of pandemic mortality based on the newly-released final data on deaths in 2009 and 2010 in the United States.
We obtained data on influenza and pneumonia deaths from the National Center for Health Statistics (NCHS). Age- and sex-specific death rates, and age-standardized death rates, were calculated. Using negative binomial Serfling-type methods, excess mortality was calculated separately by sex and age groups.
In many age groups, observed pneumonia and influenza cause-specific mortality rates in October and November 2009 broke month-specific records since 1959 when the current series of detailed US mortality data began. Compared to the typical pattern of seasonal flu deaths, the 2009 pandemic age-specific mortality, as well as influenza-attributable (excess) mortality, skewed much younger. We estimate 2,634 excess pneumonia and influenza deaths in 2009-10; the excess death rate in 2009 was 0.79 per 100,000.
Pandemic influenza mortality skews younger than seasonal influenza. This can be explained by a protective effect due to antigenic cycling. When older cohorts have been previously exposed to a similar antigen, immune memory results in lower death rates at older ages. Age-targeted vaccination of younger people should be considered in future pandemics.
PMID: 23717567 [PubMed - as supplied by publisher]