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Severe influenza greater burden in LMICs than in wealthier countries
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Three recent studies underscore the significant burden of severe influenza in developing countries compared with wealthier ones.
The data show that health care officials must conduct thorough surveillance and address risk factors for severe influenza in low- and middle-income countries (LMICs) as is done in high-income countries (HICs), they wrote in Influenza and Other Respiratory Viruses.
Researchers in one of the studies found that HIV infection and pregnancy, among other conditions, are significantly greater risk factors for severe influenza in LMICs than in HICs.
“Continued investment in capacity building for influenza surveillance is fundamental to understanding the role of influenza in association with serious outcomes; the need is universal but urgent in LMIC,” researcher Brenda L. Coleman, PhD, MSc, a clinical scientist in the infectious disease epidemiology research at Mount Sinai Hospital in Toronto, Ontario, and colleagues wrote. “Although pregnant women, people with neurological conditions and people with immune-suppressing conditions including HIV/AIDS are included in current recommendations for vaccination against influenza in HIC, governments and establishments such as WHO should ensure they are also considered as high-priority groups for vaccination and treatment in LMIC.”
The researchers analyzed previous literature on influenza in LMICs and HICs and compared outcomes according to risk factor. They defined severe outcomes as admission to an intensive care unit (ICU) and/or death. Coleman and colleagues included 198 studies, 141 of which were conducted in HICs and 57 in LMICs.
In addition to severe outcomes, the researchers also assessed hospitalization due to influenza. They found that, in HICs, people with HIV did not have a greater risk for influenza hospitalization than those without the virus. However, people with HIV in LMICs had significantly higher risk for influenza hospitalization, with a pooled relative risk (pRR) that ranged between 4.2 and 7.5, depending on the season, according to data in one LMIC study.
In HICs, children aged younger than 5 years had less risk for a severe influenza outcome compared with children aged 5 years to 19 years. Conversely, children aged younger than 5 years in LMICs had a greater risk for severe influenza outcomes than older children (pRR = 1.52).
Pregnant women in HICs had no more risk for severe influenza outcomes than other patients with the virus. But in LMICs, pregnant women were much more likely to have severe outcomes (pRR = 1.66).
Finally, people with HIV in LMICs were more than twice as likely to have severe outcomes than those without HIV (pRR = 2.17). The risk was not significantly higher for people with HIV in HICs, the researchers said.
In two additional studies, researchers addressed what they called substantial burdens of influenza in LMICs and a need for greater intervention.
In one study, the researchers estimated influenza-associated mortality in Bangladesh between 2010 and 2012. They estimated the influenza-associated mortality rate for children aged younger than 5 years was six deaths per 100,000 children from 2010 to 2011, and 13 deaths per 100,000 children from 2011 to 2012. Among people aged older than 60 years, the researchers estimated that the mortality rate was 41 deaths per 100,000 people from 2010 to 2011 and 88 deaths per 100,000 people from 2011 to 2012.
In another study, researchers addressed the burden of hospitalization for influenza-associated severe acute respiratory illness (SARI) in Rwanda from 2012 to 2014. They estimated that SARI was behind 77.2% of respiratory admissions among patients aged younger than 5 years and 59.2% of admissions among those aged 5 years and older.
Of SARI cases that were tested, influenza accounted for 5.7% among children aged younger than 5 years and 7.8% among children aged 5 years and older. – by Joe Green
References:
Ahmed M, et al. Influenza Other Respir Viruses. 2017;doi:10.1111/irv.12490.
Coleman BL, et al. Influenza Other Respir Viruses. 2017;doi:10.1111/irv.12504.
Nyamusore J, et al. Influenza Other Respir Viruses. 2017;doi:10.1111/irv.12494.
Disclosures: The authors report no relevant financial disclosures.
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