Characterizing the Epidemiology of the 2009 Influenza A/H1N1 Pandemic in Mexico
Background:
Mexico's local and national authorities initiated an intense public
health response during the early stages of the 2009 A/H1N1 pandemic. In this
study we analyzed the epidemiological patterns of the pandemic during
April–December 2009 in Mexico and evaluated the impact of nonmedical
interventions, school cycles, and demographic factors on influenza
transmission.
Methods and Findings:
We used influenza surveillance data compiled by the Mexican Institute for
Social Security, representing 40% of the population, to study
patterns in influenza-like illness (ILIs) hospitalizations, deaths, and
case-fatality rate by pandemic wave and geographical region. We also
estimated the reproduction number (R) on the basis of the growth rate of
daily cases, and used a transmission model to evaluate the effectiveness of
mitigation strategies initiated during the spring pandemic wave. A total of
117,626 ILI cases were identified during April–December 2009, of which
30.6% were tested for influenza, and 23.3% were positive for
the influenza A/H1N1 pandemic virus. A three-wave pandemic profile was
identified, with an initial wave in April–May (Mexico City area), a
second wave in June–July (southeastern states), and a geographically
widespread third wave in August–December. The median age of laboratory
confirmed ILI cases was ∼18 years overall and increased to ∼31 years
during autumn (p<0.0001). The case-fatality ratio among
ILI cases was 1.2% overall, and highest (5.5%) among people
over 60 years. The regional R estimates were 1.8–2.1, 1.6–1.9,
and 1.2–1.3 for the spring, summer, and fall waves, respectively. We
estimate that the 18-day period of mandatory school closures and other
social distancing measures implemented in the greater Mexico City area was
associated with a 29%–37% reduction in influenza
transmission in spring 2009. In addition, an increase in R was observed in
late May and early June in the southeast states, after mandatory school
suspension resumed and before summer vacation started. State-specific fall
pandemic waves began 2–5 weeks after school reopened for the fall
term, coinciding with an age shift in influenza cases.
Conclusions:
We documented three spatially heterogeneous waves of the 2009 A/H1N1 pandemic
virus in Mexico, which were characterized by a relatively young age
distribution of cases. Our study highlights the importance of school cycles
on the transmission dynamics of this pandemic influenza strain and suggests
that school closure and other mitigation measures could be useful to
mitigate future influenza pandemics.
:
Please see later in the article for the Editors' Summary
Vyšlo v časopise:
Characterizing the Epidemiology of the 2009 Influenza A/H1N1 Pandemic in Mexico. PLoS Med 8(5): e32767. doi:10.1371/journal.pmed.1000436
Kategorie:
Research Article
prolekare.web.journal.doi_sk:
https://doi.org/10.1371/journal.pmed.1000436
Souhrn
Background:
Mexico's local and national authorities initiated an intense public
health response during the early stages of the 2009 A/H1N1 pandemic. In this
study we analyzed the epidemiological patterns of the pandemic during
April–December 2009 in Mexico and evaluated the impact of nonmedical
interventions, school cycles, and demographic factors on influenza
transmission.
Methods and Findings:
We used influenza surveillance data compiled by the Mexican Institute for
Social Security, representing 40% of the population, to study
patterns in influenza-like illness (ILIs) hospitalizations, deaths, and
case-fatality rate by pandemic wave and geographical region. We also
estimated the reproduction number (R) on the basis of the growth rate of
daily cases, and used a transmission model to evaluate the effectiveness of
mitigation strategies initiated during the spring pandemic wave. A total of
117,626 ILI cases were identified during April–December 2009, of which
30.6% were tested for influenza, and 23.3% were positive for
the influenza A/H1N1 pandemic virus. A three-wave pandemic profile was
identified, with an initial wave in April–May (Mexico City area), a
second wave in June–July (southeastern states), and a geographically
widespread third wave in August–December. The median age of laboratory
confirmed ILI cases was ∼18 years overall and increased to ∼31 years
during autumn (p<0.0001). The case-fatality ratio among
ILI cases was 1.2% overall, and highest (5.5%) among people
over 60 years. The regional R estimates were 1.8–2.1, 1.6–1.9,
and 1.2–1.3 for the spring, summer, and fall waves, respectively. We
estimate that the 18-day period of mandatory school closures and other
social distancing measures implemented in the greater Mexico City area was
associated with a 29%–37% reduction in influenza
transmission in spring 2009. In addition, an increase in R was observed in
late May and early June in the southeast states, after mandatory school
suspension resumed and before summer vacation started. State-specific fall
pandemic waves began 2–5 weeks after school reopened for the fall
term, coinciding with an age shift in influenza cases.
Conclusions:
We documented three spatially heterogeneous waves of the 2009 A/H1N1 pandemic
virus in Mexico, which were characterized by a relatively young age
distribution of cases. Our study highlights the importance of school cycles
on the transmission dynamics of this pandemic influenza strain and suggests
that school closure and other mitigation measures could be useful to
mitigate future influenza pandemics.
:
Please see later in the article for the Editors' Summary
Zdroje
1. Chowell
G
Bertozzi
SM
Colchero
MA
Lopez-Gatell
H
Alpuche-Aranda
C
2009
Severe respiratory disease concurrent with the circulation of
H1N1 influenza.
N Engl J Med
361
674
679
2. Perez-Padilla
R
de la Rosa-Zamboni
D
Ponce de Leon
S
Hernandez
M
Quinones-Falconi
F
2009
Pneumonia and respiratory failure from swine-origin influenza A
(H1N1) in Mexico.
N Engl J Med
361
680
689
3. Gomez-Gomez
A
Magana-Aquino
M
Garcia-Sepulveda
C
Ochoa-Perez
UR
Falcon-Escobedo
R
2010
Severe pneumonia associated with pandemic (H1N1) 2009 outbreak,
San Luis Potosi, Mexico.
Emerg Infect Dis
16
27
34
4. 2009
Swine influenza A (H1N1) infection in two children--Southern
California, March-April 2009.
MMWR Morb Mortal Wkly Rep
58
400
402
5. 2009
Outbreak of swine-origin influenza A (H1N1) virus infection -
Mexico, March-April 2009.
MMWR Morb Mortal Wkly Rep
58
467
470
6. Cordova-Villalobos
JA
Sarti
E
Arzoz-Padres
J
Manuell-Lee
G
Mendez
JR
2009
The influenza A(H1N1) epidemic in Mexico. Lessons
learned.
Health Res Policy Syst
7
21
7. Bootsma
MC
Ferguson
NM
2007
The effect of public health measures on the 1918 influenza
pandemic in U.S. cities.
Proc Natl Acad Sci U S A
104
7588
7593
8. Shaman
J
Kohn
M
2009
Absolute humidity modulates influenza survival, transmission, and
seasonality.
Proc Natl Acad Sci U S A
106
3243
3248
9. Shaman
J
Pitzer
VE
Viboud
C
Grenfell
BT
Lipsitch
M
2010
Absolute humidity and the seasonal onset of influenza in the
continental United States.
PLoS Biol
8
e1000316
doi:10.1371/journal.pbio.1000316
10. 2010
H1N1 Flu.
Atlanta (Georgia)
Centers for Disease Control and Prevention
11. Fraser
C
Donnelly
CA
Cauchemez
S
Hanage
WP
Van Kerkhove
MD
2009
Pandemic potential of a strain of influenza A (H1N1): early
findings.
Science
324
1557
1561
12. Ghani
AC
Baguelin
M
Griffin
J
Flasche
S
Pebody
R
2009
The early transmission dynamics of H1N1pdm influenza in the
United Kingdom.
PLoS Curr Influenza
doi:10.1371/currents.RRN1130
RRN1130
13. Yang
Y
Sugimoto
JD
Halloran
ME
Basta
NE
Chao
DL
2009
The transmissibility and control of pandemic influenza A (H1N1)
virus.
Science
326
729
733
14. Nishiura
H
Castillo-Chavez
C
Safan
M
Chowell
G
2009
Transmission potential of the new influenza A(H1N1) virus and its
age-specificity in Japan.
Euro Surveill
14
15. Laguna-Torres
VA
Gomez
J
Aguilar
PV
Ampuero
JS
Munayco
C
2010
Changes in the viral distribution pattern after the appearance of
the novel influenza A H1N1 (pH1N1) virus in influenza-like illness patients
in Peru.
PLoS One
5
e11719
doi:10.1371/journal.pone.0011719
16. Valdivia
A
Lopez-Alcalde
J
Vicente
M
Pichiule
M
Ruiz
M
2010
Monitoring influenza activity in Europe with Google Flu Trends:
comparison with the findings of sentinel physician networks - results for
2009-10.
Euro Surveill
15
17. Echevarria-Zuno
S
Mejia-Arangure
JM
Mar-Obeso
AJ
Grajales-Muniz
C
Robles-Perez
E
2009
Infection and death from influenza A H1N1 virus in Mexico: a
retrospective analysis.
Lancet
374
2072
2079
18. CONAPO
2010
Mexico City: Consejo Nacional de Poblacion, Mexico
19. 2009
Centers for Disease Control and Prevention. Serum cross-reactive
antibody response to a novel influenza A (H1N1) virus after vaccination with
seasonal influenza vaccine.
MMWR Morb Mortal Wkly Rep
58
521
524
20. Chowell
G
Bettencourt
LM
Johnson
N
Alonso
WJ
Viboud
C
2008
The 1918-1919 influenza pandemic in England and Wales: spatial
patterns in transmissibility and mortality impact.
Proc Biol Sci
275
501
509
21. Wallinga
J
Lipsitch
M
2007
How generation intervals shape the relationship between growth
rates and reproductive numbers.
Proc Biol Sci
274
599
604
22. Chowell
G
Viboud
C
Simonsen
L
Miller
MA
Acuna-Soto
R
2010
Mortality patterns associated with the 1918 influenza pandemic in
Mexico: evidence for a spring herald wave and lack of preexisting immunity
in older populations.
J Infect Dis
202
567
575
23. Chowell
G
Nishiura
H
Bettencourt
LM
2007
Comparative estimation of the reproduction number for pandemic
influenza from daily case notification data.
J R Soc Interface
4
155
166
24. Cauchemez
S
Donnelly
CA
Reed
C
Ghani
AC
Fraser
C
2009
Household transmission of 2009 pandemic influenza A (H1N1) virus
in the United States.
N Engl J Med
361
2619
2627
25. Cowling
BJ
Chan
KH
Fang
VJ
Lau
LL
So
HC
2010
Comparative epidemiology of pandemic and seasonal influenza A in
households.
N Engl J Med
362
2175
2184
26. Monto
AS
Koopman
JS
Longini
IM
Jr
1985
Tecumseh study of illness. XIII. Influenza infection and disease,
1976-1981.
Am J Epidemiol
121
811
822
27. Cauchemez
S
Ferguson
NM
Wachtel
C
Tegnell
A
Saour
G
2009
Closure of schools during an influenza pandemic.
Lancet Infect Dis
9
473
481
28. Chao
DL
Elizabeth Halloran
M
Longini
IM
Jr
2010
School opening dates predict pandemic influenza A(H1N1) outbreaks
in the United States.
J Infect Dis
202
877
880
29. Cauchemez
S
Valleron
AJ
Boelle
PY
Flahault
A
Ferguson
NM
2008
Estimating the impact of school closure on influenza transmission
from Sentinel data.
Nature
452
750
754
30. Gomez
J
Munayco
C
Arrasco
J
Suarez
L
Laguna-Torres
V
2009
Pandemic influenza in a southern hemisphere setting: the
experience in Peru from May to September, 2009.
Euro Surveill
14
31. Nishiura
H
2010
Case fatality ratio of pandemic influenza.
Lancet Infect Dis
10
443
444
32. Baker
MG
Wilson
N
Huang
QS
Paine
S
Lopez
L
2009
Pandemic influenza A(H1N1)v in New Zealand: the experience from
April to August 2009.
Euro Surveill
14
33. Wu
JT
Cowling
BJ
Lau
EH
Ip
DK
Ho
LM
2010
School closure and mitigation of pandemic (H1N1) 2009, Hong
Kong.
Emerg Infect Dis
16
538
541
34. Hens
N
Ayele
GM
Goeyvaerts
N
Aerts
M
Mossong
J
2009
Estimating the impact of school closure on social mixing
behaviour and the transmission of close contact infections in eight European
countries.
BMC Infect Dis
9
187
35. Langmuir
AD
Pizzi
M
Trotter
WY
Dunn
FL
1958
[Asian influenza surveillance.].
Public Health Rep
73
114
120
36. Dunn
FL
Carey
DE
Cohen
A
Martin
JD
1959
Epidemiologic studies of Asian influenza in a Louisiana
parish.
Am J Hyg
70
351
371
37. Pourbohloul
B
Ahued
A
Davoudi
B
Meza
R
Meyers
LA
2009
Initial human transmission dynamics of the pandemic (H1N1) 2009
virus in North America.
Influenza Other Respi Viruses
3
215
222
38. Boelle
PY
Bernillon
P
Desenclos
JC
2009
A preliminary estimation of the reproduction ratio for new
influenza A(H1N1) from the outbreak in Mexico, March-April
2009.
Euro Surveill
14
39. Nishiura
H
Chowell
G
Safan
M
Castillo-Chavez
C
2010
Pros and cons of estimating the reproduction number from early
epidemic growth rate of influenza A (H1N1) 2009.
Theor Biol Med Model
7
1
40. Paine
S
Mercer
GN
Kelly
PM
Bandaranayake
D
Baker
MG
2010
Transmissibility of 2009 pandemic influenza A(H1N1) in New
Zealand: effective reproduction number and influence of age, ethnicity and
importations.
Euro Surveill
15
41. McBryde
E
Bergeri
I
van Gemert
C
Rotty
J
Headley
E
2009
Early transmission characteristics of influenza A(H1N1)v in
Australia: Victorian state, 16 May - 3 June 2009.
Euro Surveill
14
42. Munayco
CV
Gomez
J
Laguna-Torres
VA
Arrasco
J
Kochel
TJ
2009
Epidemiological and transmissibility analysis of influenza
A(H1N1)v in a southern hemisphere setting: Peru.
Euro Surveill
14
43. Pedroni
E
Garcia
M
Espinola
V
Guerrero
A
Gonzalez
C
2010
Outbreak of 2009 pandemic influenza A(H1N1), Los Lagos, Chile,
April-June 2009.
Euro Surveill
15
44. Tuite
AR
Greer
AL
Whelan
M
Winter
AL
Lee
B
2010
Estimated epidemiologic parameters and morbidity associated with
pandemic H1N1 influenza.
CMAJ
182
131
136
45. White
LF
Wallinga
J
Finelli
L
Reed
C
Riley
S
2009
Estimation of the reproductive number and the serial interval in
early phase of the 2009 influenza A/H1N1 pandemic in the
USA.
Influenza Other Respi Viruses
3
267
276
46. Lessler
J
Reich
NG
Cummings
DA
Nair
HP
Jordan
HT
2009
Outbreak of 2009 pandemic influenza A (H1N1) at a New York City
school.
N Engl J Med
361
2628
2636
47. 2009
Current situation of the 2009 H1N1pdm influenza pandemic in
Mexico [in Spanish].
Mexico City
Secretaria de Salud
48. 2010
Situacion de influenza A(H1N1) - reporte
01/26/2010.
Santiago (Chile)
Ministerio de Salud de Chile
49. 2010
Situacion de influenza A(H1N1) - parte 87.
Buenos Aires
Ministerio de Salud de Argentina
50. Webb
SA
Pettilä
A
Seppelt
I
Bellomo
R
2009
Critical care services and 2009 H1N1 influenza in Australia and
New Zealand.
N Engl J Med
361
1925
34
51. Bishop
JF
Murnane
MP
Owen
R
2009
Australia's winter with the 2009 pandemic influenza A (H1N1)
virus.
N Engl J Med
361
2591
2594
52. Miller
MA
Viboud
C
Balinska
M
Simonsen
L
2009
The signature features of influenza pandemics--implications for
policy.
N Engl J Med
360
2595
2598
53. Chowell
G
Ammon
CE
Hengartner
NW
Hyman
JM
2006
Estimation of the reproductive number of the Spanish flu epidemic
in Geneva, Switzerland.
Vaccine
24
6747
6750
54. Andreasen
V
Viboud
C
Simonsen
L
2008
Epidemiologic characterization of the 1918 influenza pandemic
summer wave in Copenhagen: implications for pandemic control
strategies.
J Infect Dis
197
270
278
55. Ayora-Talavera
G
Gongora-Biachi
RA
Lopez-Martinez
I
Moguel-Rodriguez
W
Perez-Carrillo
H
2002
Detection of human influenza virus in Yucatan,
Mexico.
Rev Invest Clin
54
410
414
56. Shaman
J
Goldstein
E
Lipsitch
M
2011
Absolute humidity and pandemic versus epidemic
influenza.
Am J Epidemiol
173
127
135
57. Lipsitch
M
Viboud
C
2009
Influenza seasonality: lifting the fog.
Proc Natl Acad Sci U S A
106
3645
3646
58. Viboud
C
Bjornstad
ON
Smith
DL
Simonsen
L
Miller
MA
2006
Synchrony, waves, and spatial hierarchies in the spread of
influenza.
Science
312
447
451
59. Eggo RM, Cauchemez S, Ferguson NM Spatial dynamics of the 1918
influenza pandemic in England, Wales and the United States.
J R Soc Interface
8
233
243
60. Nishiura
H
Chowell
G
2008
Rurality and pandemic influenza: geographic heterogeneity in the
risks of infection and death in Kanagawa, Japan (1918-1919).
N Z Med J
121
18
27
61. Reed
C
Angulo
FJ
Swerdlow
DL
Lipsitch
M
Meltzer
MI
2009
Estimates of the prevalence of pandemic (H1N1) 2009, United
States, April-July 2009.
Emerg Infect Dis
15
2004
2007
62. Presanis
AM
De Angelis
D
Hagy
A
Reed
C
Riley
S
2009
The severity of pandemic H1N1 influenza in the United States,
from April to July 2009: a Bayesian analysis.
PLoS Med
6
e1000207
doi:10.1371/journal.pmed.1000207
63. Libster
R
Bugna
J
Coviello
S
Hijano
DR
Dunaiewsky
M
2010
Pediatric hospitalizations associated with 2009 pandemic
influenza A (H1N1) in Argentina.
N Engl J Med
362
45
55
64. Wu
JT
Ma
ES
Lee
CK
Chu
DK
Ho
PL
2010
The infection attack rate and severity of 2009 pandemic H1N1
influenza in Hong Kong.
Clin Infect Dis
51
1184
1191
65. Louie
JK
Acosta
M
Winter
K
Jean
C
Gavali
S
2009
Factors associated with death or hospitalization due to pandemic
2009 influenza A(H1N1) infection in California.
JAMA
302
1896
1902
66. Hardelid
P
Andrews
N
Hoschler
K
Stanford
E
Baguelin
M
2010
Assessment of baseline age-specific antibody prevalence and
incidence of infection to novel influenza AH1N1 2009.
Health Technol Assess
14
115
192
67. Olson
DR
Simonsen
L
Edelson
PJ
Morse
SS
2005
Epidemiological evidence of an early wave of the 1918 influenza
pandemic in New York City.
Proc Natl Acad Sci U S A
102
11059
11063
68. Valleron
AJ
Cori
A
Valtat
S
Meurisse
S
Carrat
F
2010
Transmissibility and geographic spread of the 1889 influenza
pandemic.
Proc Natl Acad Sci U S A
107
8778
8781
69. World Health Organization (WHO)
2010
Aug
10
H1N1 in post-pandemic period.
Available: http://www.who.int/mediacentre/news/statements/2010/h1n1_vpc_20100810/en/index.html.
Štítky
Interné lekárstvoČlánok vyšiel v časopise
PLOS Medicine
2011 Číslo 5
- Jak rozpoznat pacienty s familiární hypercholesterolémií ve své praxi
- Myasthenia gravis: kombinace chirurgie a farmakoterapie jako nejefektivnější modalita?
- Statinová intolerance
- Liečba bolesti po jednodňovej chirurgii
- Mutace v genu PCSK9 zodpovědné za rozvoj familiární hypercholesterolémie
Najčítanejšie v tomto čísle
- Low-Dose Adrenaline, Promethazine, and Hydrocortisone in the Prevention of Acute Adverse Reactions to Antivenom following Snakebite: A Randomised, Double-Blind, Placebo-Controlled Trial
- Effectiveness of Early Antiretroviral Therapy Initiation to Improve Survival among HIV-Infected Adults with Tuberculosis: A Retrospective Cohort Study
- Primary Prevention of Gestational Diabetes Mellitus and Large-for-Gestational-Age Newborns by Lifestyle Counseling: A Cluster-Randomized Controlled Trial
- Meta-analyses of Adverse Effects Data Derived from Randomised Controlled Trials as Compared to Observational Studies: Methodological Overview