Seasonal pattern of influenza activity
in the Philippines (2006-2008):
Research Implications to
recommendations for influenza
vaccination
Lucero MG, Inobaya A, Bautista A, Tan A, Arguelles V, Dureza C,
Mercado E, Barrientos A, Tallo V and Olveda RM
Research Institute for Tropical Medicine
National Influenza Center, Philippines
Background
• Influenza virus infection – extensive studies in
temperate countries
• Few studies in tropical countries like the
Philippines
• National Influenza surveillance established in
2005 after the creation of an NIC.
Objective
To present the results of the national
influenza surveillance from 2006 to 2008 and
determine if a seasonal pattern of influenza
infection is observed in the Philippines.
Methods
• Study Design: Retrospective analysis
• Database: ILI surveillance data from 20062008
• Sentinel sites: health centers and OPD clinics
of hospitals in 11 regions in the Philippines
2008:
Influenza
Burden of Disease Study (BOD)
Baguio City
Surveillance Procedures
ILI
InfluenzaLike
Illness
Clinical
information
in Case
Report Forms
Nasopharyngeal or
Oropharyngeal
Swab
Influenza virus identification
• Virus isolation in cell culture for
Influenza virus and other respiratory
viruses (starting 2006 to present)
• Real-time PCR assay: H1, H3 and
avian H5 subtypes – for 25% of
swabs in BOD study in late 2008
and for suspected outbreaks during
routine surveillance
Results
Influenza-Like Illness (ILI) Surveillance in the Philippines, 2005 - 2008
Distribution of Influenza-positive ILI cases by morbidity week from 2006-2008
National Influenza Surveillance Network
Influenza types identified in the Philippines from 2006 to 2008
A Brisbane/59/2007(H1N1)-like
A New Caledonia/20/99(H1N1)-like
A H3 (PCR Detections)
B Malaysia/2506/2004-like
B Lineage not Determined
Number Influenza Positive Cases
60
A Brisbane/10/2007(H3N2)-like
A New York/55/2004(H3N2)-like
A not Subtyped
B Shanghai/361/2002-like
Moving Ave 4 Weeks (Influenza Positives)
A Wisconsin/67/2005(H3N2)-like
A H1 (PCR Detections)
A Unsubtypeable
B Florida/4/2006-like
2007
2006
2008
50
40
30
20
10
0
1
8
15
22
29
36
43
May July Sep Nov
50
5
12
19
26
33
40
May July Sep Nov
47
2
9
16
23
30
37
44
May July Sep Nov
51
VACCINE COMPOSITION RECOMMENDATIONS FROM WHO
and PHILIPPINE INFLUENZA STRAINS IDENTIFIED
2005-2006
2006-2007
2007-2008
Northern
Hemisphere
A/New Caledonia/20/99(H1N1)-like
A/California/7/2004(H3N2)-like
B/Shanghai/361/2002-like
A/New Caledonia/20/99(H1N1)-like
A/Wisconsin/67/2005 (H3N2)-like
B/Malaysia/2506/2004-like
A/Solomon Islands/3/2006 (H1N1)-like
A/Wisconsin/67/2005 (H3N2)-like
B/Malaysia/2506/2004-like
PHILIPPINE
INFLUENZA
STRAINS
(SORTED-HIGHEST TO LOWEST)
A New Caledonia/20/99(H1N1)-like
B Malaysia/2506/2004-like
A New York/55/2004(H3N2)-like
B Shanghai/361/2002-like
(SORTED-HIGHEST TO LOWEST)
A New York/55/2004(H3N2)-like
A New Caledonia/20/99(H1N1)-like
B Shanghai/361/2002-like
B Malaysia/2506/2004-like
A Wisconsin/67/2005(H3N2)-like
(SORTED-HIGHEST TO LOWEST)
B Florida/4/2006-like
B Shanghai/361/2002-like
A Brisbane/10/2007(H3N2)-like
B Malaysia/2506/2004-like
A Brisbane/59/2007(H1N1)-like
A Wisconsin/67/2005(H3N2)-like
2006
Southern
Hemisphere
A/New Caledonia/20/99(H1N1)-like
A/California/7/2004(H3N2)-like
B/Malaysia/2506/2004-like
2007
A/New Caledonia/20/99(H1N1)-like
A/Wisconsin/67/2005(H3N2)-like
B/Malaysia/2506/2004-like
2008
A/Solomon Islands/3/2006 (H1N1)-like
A/Brisbane/10/2007 (H3N2)-like
B/Florida/4/2006-like
Summary of the results of the 3-year surveillance:
1. Influenza virus activity is found all throughout the year
but activity is highest starting 3rd week of May and
continues till the months of October or November with
usually two peaks observed during this period.
2. Different dominant organisms are associated with each
peak.
3. Not all vaccine composition recommendations matched
influenza strains identified during the years studied.
Dominant influenza strain for 2007 was not covered by
the vaccine recommendations for that year. Dominant
flu strain for 2008 was covered only by Southern
Hemisphere vaccine recommendations.
Implications of findings of 3-year surveillance:
1. Influenza vaccination should be given before May of
each year or before school opening in June.
2. NIC should continue its activities of timely submission
of data and isolates to WHO for better understanding
of vaccine recommendations for the Philippines and
other Asian countries.
3. Northern or Southern Hemisphere vaccine
recommendation to be followed?
4. Limitation of study: Only mild ILI cases studied. No
data on hospital SARI cases.
Acknowledgment:
1. Dr. Eric Tayag: National Epidemiology Center (NEC),
Department of Health
2. NEC Epidemiologists
3. Regional Health Officers, Provincial Health Officers,
RESU, CESU, Chief of Participating Hospitals,
Participating Health Center personnel of Regions I, II,
III, V, VI, VII, IX, CAR, NCR, X, XI, XII, Participating
Tertiary Hospitals in NCR and Baguio City
4. Influenza Surveillance Officers
5. RITM-NIC personnel
Acknowledgment:
Centers for Disease Control and
Prevention (CDC), Atlanta, USA
WHO
CHEERS !
THANK YOU
7-10 June 2011
rolvedamd_ritm_doh@yahoo.com