1. Influenza A H1N1: Risk factors and
Response Actions
Mónica C. Del Moral
Department of Biology
University of Puerto Rico at Cayey
Review Paper

2. Outline
 Background information
 Influenza A H1N1
 Strain
 Relation of different strains
 2009 H1N1
 According to studies- Risk factors observed
 Vaccine and Control measures

3. Introduction

4. Background information:
Influenza
 Influenza- contagious airborne
disease that expresses febrile
illness. (Derlet and Nguyen, 2013)
 Symptoms range from fatigue to
respiratory failure or death
 Seasonal strains are
common, but deadly ones have
emerged (Derlet and Nguyen, 2013)
 Pandemics- influenza virus +
hemagglutinin (Garten et al, 2009)
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grama_de_s%C3%ADntomas_de_la_gripe
_AH1N1.svg

5. Background information: Strains
 Lethal strains lead to pandemics- 1918 Spanish flu
(Kilbourne, 2006)
 1/3 of the world infected
 50 million deaths (Taubenberger and Morens, 2006)
 Strains affect animals- species specific (Derlet and
Nguyen, 2013)
 Avian influenza
 Swine influenza
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6. Background information: Avian, Swine and
Humans
(Taubenberger and
Morens, 2006)
 1918- relation
between avian and
swine was unknown
 1930’s- viruses were
isolated
 Transmission- pigs to
humans (Stuart et al.
http://www.thepattersonfoundation.org/
2013)
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snowbirds-seagulls-and-piegons/birds-

7. 2009 H1N1
 Mix of swine, avian and human
gene segments (Derlet and
Nguyen, 2013)
 Start- cases identified in
Mexico (Stuart et al., 2013)
(Michaelis et al. 2009)
 The WHO stated that these
viruses were not previously
detected
 Majority of cases- healthy
young adults
 WHO- pandemic alert level 6
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June 11 2009
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8. Vulnerability and Risk Factors
 1918 Spanish flu and the First World War
(Erkoreka, 2009)
 Many soldiers living in poor conditions, harsh
climate, wild animals, etc.
 Similarity with 2009

9. Vulnerability and Risk Factors
 New Mexico study- relation between racial/ethnic
groups and the outcome of the infection (Thompson
et.al 2011)
 NMDOH- developed hospital surveillance system
 Results:
 American Indians- highest rate of related hospitalizations
 Age- young (hospitalization), older (mechanical ventilation)
 High risk medical conditions- most common were diabetes,
asthma, and chronic lung diseases
 Obesity (mechanical ventilation, not death)

10. Vulnerability and Risk Factors
 Outbreak in a Germany hospital (Grund et al.
2010)
 In immunocompromised ward- 5 infected people
 To identify infection- tested to see the viral RNA and
virus antigen:
 Nasopharyngeal swabs
 Bronchoalveolar or pharyngeal lavages
 Healthcare workers were also tested- if results were
positive control measures would be implemented
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11. Vulnerability and Risk Factors
 Control measures such as:
 Isolation of influenza positive patients
 Hand washing
 and others
 Results were negative for influenza, but positive for
antibodies against influenza A and B
 It is suggested that infection occurred within and
spread through staff

12. Response

13. Vaccine implementation
 Canadian study in 2011 (Conway et al. 2011)
designed a model to visualize the transmission of
Pandemic H1N1 in urban sites
 Model included: demographic and behavioral
factors
 Strategies:
 Actual coverage
 Uniform Coverage
 Parents and Children
 Parents-and-children/Actual sequence

14. Vaccine implementation
 Stratified population:
 Susceptible
 Vaccinated
 Exposed
 Pre-symptomatically infectious
 Infectious
 Immune
 Activity level and social contact
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15. Vaccine implementation
 Assumed and confirmed: with vaccine there
would be a reduction of 90% risk of infection
 Diversifying campaign start dates were tested
 Results confirmed vaccine efficacy and strategy
used- relative to moment of campaign
implementation (prior or on peak)

16. Control Measures
 CDC (Stuart et al. 20013) makes
recommendations to manage the H1N1 virus:
 Isolation for approximately 7 days
 Inform and report case to a health care provider
 If in social contact, wear masks
 Strict hand washing
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17. Summary
 Out of patterns studied, risk factors can be identified
 Social interaction- 1918 and 2009
 Age, weight, income, race/ethnicity, and high risk
medical conditions
 Vaccine campaign timing varies efficacy
 Key control measures- isolation and hand wash
and/or disinfection

18. Conclusion
 We can now:
 identify some high risk groups to provide them help
with prevention plans and treatments
 identify risk factors to either avoid them or be alert
of cases around and reduce chance of infection
 be prepared to face the infection with common
hygiene practices and proper vaccine campaigns.

19. References
 Anonymous. Influenza-like illness in the United States and




Mexico. World Health Organization. [Cited 2013 Nov/8].
Available source at:
http://www.who.int/csr/don/2009_04_24/en/index.html
Brook I. Last update: April/4/2013. Pediatric Influenza. [Internet].
[Cited 2013 Nov/8]. Available source at:
http://emedicine.medscape.com/article/972269overview#aw2aab6b2b2
CDC. Interim Guidance for Clinicians on the Prevention and
Treatment of Swine-Origin Influenza Virus Infection in Young
Children. Centers for Disease Control and Prevention. Available
source at: http://www.cdc.gov/swineflu/childrentreatment.htm
Conway J, Tuite A, Fisman D, Hupert N, Meza R, Davoudi B,
English K, Driessche P, Brauer F, Ma J et al. 2011.Vaccination
against 2009 pandemic H1N1 in a population dynamical model
of Vancouver, Canada: timing is everything. BMC Public Health
11: 1-14
Derlet R, Nguyen N. Last update: Nov/4/2013. Influenza.
[Internet]. [Cited 2013 Nov/8]. Available source at:
http://emedicine.medscape.com/article/219557-overview#a0101

20. References
 Erkoreka A. 2009. Origins of the Spanish Influenza pandemic
(1918–1920) and its relation to the First World War. Journal of
Molecular and Genetic Medicine 3(2): 190-194. Available source
at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805838/
 Garten R, Davis CT, Russell C, Shu Bo, Lindstrom S, Balish
A, Sessions W, Xu X, Skepner E, Deyde V, et al. 2009. Antigenic
and Genetic Characteristics of the Early Isolates of Swine-Origin
2009 A (H1N1) Influenza Viruses Circulating in Humans. Science
325(5937): 197-201. Available source at:
http://dx.doi.org/10.1126%2Fscience.1176225
 Grund S, Roggendorf M, Schweiger. 2010. Outbreak of influenza
virus A/H1n1 in a hospital ward for immunocompromised
patients. Archives of Virology 155: 1797-1802
 Kilbourne E. 2006. Influenza Pandemics of the 20th Century.
Emerg Infect Dis 12(1):9-14. [Cited 2013 Nov/8] Available source
at:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291411/?report=r
eader#!po=81.2500 . http://dx.doi.org/10.3201/eid1201.051254

21. References
 Michaelis M, Doerr HW, Cinatl J. 2009. An Influenza A H1N1 Virus
Revival-Pandemic H1N1/09 Virus. Infection37 5(9): 381-389.
Available source at:
http://dx.doi.org.uprcdb.cayey.upr.edu:2048/10.1007/s15010-0099181-5
 Stuart M, Ross D, Wolf S. Last update: Oct/1/2013. H1N1 Influenza
(Swine Flu). [Internet]. [Cited 2013 Nov/8]. Available source at:
http://emedicine.medscape.com/article/1807048overview#aw2aab6b2b2
 Taubenberger JK, Morens DM. 2006. 1918 influenza: the mother of
all pandemics. Emerg Infect Dis 12(1): 15–22. [Cited 2013 Nov/8].
Available source at:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291398/#__ffn_sectitl.
http://dx.doi.org/10.3201/eid1209.05-0979
 Thompson D, Jungk J, Hancock E, Smelser C, Landen M, Nichols
M, Selvage D, Baumbach J, Sewell M. 2011. Risk Factors for 2009
Pandemic Influenza A (H1N1)-Related Hospitalization and Death
among Racial/Ethnic Groups in New Mexico. American Journal of
Public Health 101 (9):1776-1784. Available source at:
http://search.proquest.com.uprcdb.cayey.upr.edu:2048/docview/8847