July 26, 2009 to August 1, 2009 (Week 30)

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Pandemic (H1N1) 2009 virus Surveillance and Epidemiology

A total of 1,315 hospitalized cases, 227 cases admitted to ICU and 60 deaths of Pandemic (H1N1) 2009 have been reported to PHAC as of August 1, 2009. National abbreviated line list data was available for 6,904 cases, 1,282 (18.6%) hospitalized cases including 227 (17.7%) patients admitted to ICU and 59 deaths. The proportion of females affected, the median age and the proportion of underlying medical conditions increases with severity of illness (see table). There were 56 women pregnant out of 494 women of reproductive age for whom information on pregnancy was available. Aboriginal women make up 28.6% (16/56) of the pregnant cases in comparison with 11.2% of the overall cases reported. A high proportion of pregnant women were hospitalized (85.7%, 48/56) compared to the proportion of all cases hospitalized (18.6%). The age distribution was available for 1,241 hospitalized cases and 59 deaths from core data. The highest hospitalization rate is among the cases below 1 year of age (25.9 per 100,000) followed by the cases between 1 and 4 years of age (10.5 per 100,000). In comparison, the highest mortality rate is among the cases over 65 years of age (0.33 per 100,000), followed closely by the cases below 1 year of age (0.27 per 100,000) and cases between 45 and 64 years old (0.24 per 100,000).

There were 767 Canadian cases who were Aboriginal out of 6,904. First Nations cases (240) were from Manitoba (172), Quebec (40), British Columbia (14), Alberta (11) and Northwest Territories (3). 464 Inuit cases were from Nunavut and the rest were from Quebec (8), Alberta (3) and Northwest Territories (2). Finally, Metis cases (50) were from MB (42), AB (4), NWT (3) and BC (1). The hospitalization rate is much higher among the Nunavut residents and Inuit population (71.3 per 100,000) compared to the First Nations population (18.1 per 100,000). Among the 126 hospitalized First Nations cases, 22.2% were either admitted to ICU or died in comparison with 8.3% (3/36) of the Nunavut residents and the Inuit from other provinces. 53.3% of First Nations cases had one or more underlying conditions and 13.6% of Nunavut residents and Inuit cases had at least one underlying medical condition.

Note: Previous analyses on aboriginal populations were preliminary. Updates from some provinces and territories to the national abbreviated line-list received in the last weeks reflect the current situation.

Weekly and cumulative numbers of hospitalizations and deaths among
Pandemic (H1N1) 2009 confirmed cases, Canada, to 1^st August, 2009

Province/Territory	This week (26 July - 1 August, 2009) hospitalized cases	This week (26 July - 1 August, 2009) deaths	Cumulative hospitalized cases	Cumulative deaths cases
BC	2	0	27	2
AB	2	1	116	5
SK	0	0	22	4
MB	0	0	201	7
ON	24	1	314	19
QC	15	1	579	21
NB	0	0	1	0
NS	0	0	10	1
PE	0	0	1	0
NL	1	0	2	0
YT	0	0	0	0
NT	0	0	0	0
NU	0	0	42	1
Canada	44	3	1315	60

Note that hospitalizations are reported within the province where the case has been identified which may differ from the province of residence.
Also, Manitoba are now sending their line-list in a different format which will be included in the next report.

Descriptive characteristics of laboratory-confirmed Canadian Pandemic (H1N1) 2009 cases, hospitalized cases, cases admitted to ICU and deaths with core information available, reported to the Public Health Agency of Canada as of 1^st August 2009

	Overall cases reported (n=6,904)	Hospitalizated cases (n=1,282)	Cases admitted to ICU (n=227)	Deaths (n=59)
Females, %	51.8	51.2	60.8	64.4
Median age	18	23	40	51
Aboriginal status, %	11.2	14.1	14.5	7.4
Underlying medical conditions1, %	49.5 (585/1,182)	60.7 (509/838)	70.2 (125/178)	82.2 (37/45)
Pregnancy2, %	3.4 (56/1,659)	21.1 (48/227)	16.1 (10/62)	20.0 (2/10)
1 Among those for whom the information was provided. 2 Among women aged between 15 and 44.

Overall Influenza Summary - July 26, 2009 to August 1, 2009 (Week 30)

The overall influenza activity decreased this week ; the reported activity level (3 regions reported localized activity), the overall number of influenza outbreaks (no new outbreaks) and the national ILI consultation rate (15 consultations per 1,000 visits) are lower than last week. However, the proportion of influenza positive tests increased slightly this week.

Three regions in ON, QC & NB reported localized activity, 45 regions reported sporadic activity in BC, AB, SK, ON, QC, NB, NS, PEI, NL, YT, NT & NU and 4 regions in MB, NB & NL reported no activity (No report received from 2 regions in NL). No new influenza outbreak was reported this week.

Map of overall Influenza activity level
by provinces and territories, Week 30 Canada

No Data No Activity Sporadic Activity Localized Activity Widespread Activity

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.

Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2008-2009 (N=54)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.

Number of New Outbreaks in Long Term Care Facilities, Canada, by Report Week, 2008-2009

ILI consultation rate

This week, the ILI consultation rate was 15 consultations per 1,000 patient visits (see ILI graph) which is decreasing for the second consecutive week. The sentinel response rate was 71%.

Influenza-like illness (ILI) consultation rates, Canada, by report week,
2008-2009 compared to 1996/97 through to 2007/08 seasons

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons).
* Data arriving late may cause variations from results seen in previous weeks.

Paediatric Influenza Hospitalizations and deaths

In week 30, 3 laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network. Two of the three hospitalizations this week are due to Pandemic (H1N1) 2009 and the other to seasonal influenza A.To date this season, 725 hospitalizations have been reported; 316 (43.6%) of these hospitalizations have been due to Pandemic (H1N1) 2009. There were five deaths reported so far this season including three deaths due to Pandemic (H1N1) 2009.

Laboratory Surveillance Summary

This week, the proportion of tests that were positive for influenza was 9.9% which is higher than the previous week (see Table). A total of 511 specimen tested positive for influenza this week (all type A). 98.7% of the positive influenza A subtyped specimens were due to Pandemic (H1N1) 2009 this week.The majority (82.8%) of influenza virus detections this season have been for influenza A.

Influenza tests reported and percentage of tests positive, Canada,
by report week, 2008-2009

Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2008-2009

Weekly & Cummulative numbers of positive influenza specimens , by Provincial Laboratories

Reporting provinces	Weekly						Cumulative
	Influenza A					B	Influenza A					B
	A Total	A(H1)	A(H3)	Pand (H1N1)	A (NS)*	Total	A Total	A(H1)	A(H3)	Pand (H1N1)	A (NS)*	Total
BC	91	0	0	78	13	0	1569	9	9	505	1046	210
AB	91	0	0	30	61	0	2908	0	8	628	2272	467
SK	24	0	0	15	9	0	1406	31	79	860	436	219
MB	11	0	0	9	2	0	1061	7	35	759	260	37
ON	83	0	1	41	41	0	6712	146	157	3002	3407	1355
QC	19	0	0	0	19	0	3852	0	0	0	3852	1417
NB	115	0	0	59	56	0	481	3	3	108	367	95
NS	55	0	0	45	10	0	575	23	23	435	94	60
PE	6	3	0	3	0	0	34	8	0	12	14	9
NL	16	0	0	16	0	0	211	11	4	73	123	26
Canada	511	3	1	296	211	0	18809	238	318	6382	11871	3895

Specimens from NT, YT, and NU are sent to reference laboratories in other provinces.

Note: Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
* Not subtyped

Canadian situation

Antigenic Characterization

NML has antigenically characterized 234 Pandemic (H1N1) 2009 isolates by HI assay. The results reveal that these viruses are antigenically related to A/California/7/2009 (H1N1), which is the variant reference virus selected by WHO as a potential candidate for Pandemic (H1N1) 2009 vaccine. Antigenic characterization also indicates that these viruses are antigenically and genetically unrelated to seasonal influenza A (H1N1) viruses, which suggests that there is little or no protection to be expected from vaccination with seasonal influenza vaccine.

Antiviral Resistance

NML: All Pandemic (H1N1) 2009 viruses tested so far have been sensitive to oseltamivir (412 samples) and zanamivir (215 samples) but resistant to amantadine (283 samples).
However, Canada reported its first case of oseltamivir resistant Pandemic (H1N1) 2009 on July 21, 2009.

International update:

Global information

Pandemic influenza in pregnant women: Research conducted in the United States and published in The Lancet (July 29, 2009) has drawn attention to an increased risk of hospital admission for pregnant women infected with Pandemic (H1N1) 2009 compared to the general population. Several other countries experiencing widespread transmission of the pandemic virus have similarly reported an increased risk in pregnant women, particularly during the second and third trimesters of pregnancy.

CDC Advisors make recommendations for use of Pandemic (H1N1) 2009 Vaccine: The CDC Advisory Committee on Immunization Practices (ACIP) recommended on July 29, 2009 that Pandemic (H1N1) 2009 vaccination efforts focus on five key populations, with further prioritization of specific groups or subsets in case of limited quantities of vaccine:

• Pregnant women (priority group)
• People who live with or care for children younger than 6 months of age (priority group)
• Health care and emergency services personnel (prioritizing those with direct patient contact)
• Persons between the ages of 6 months through 24 years of age (and prioritizing those between 6 months and 4 years of age, and those ages 5 to 18 years with chronic medial conditions)
• People from ages 25 through 64 years who are at higher risk for novel H1N1 because of chronic health disorders or compromised immune systems.

Southern Hemisphere

• PAHO: As of July 29, 2009, a total of 98,179 confirmed cases have been notified in all 35 countries in the Americas Region. A total of 1,008 deaths have been detected among the confirmed cases in 20 countries of the Region. The virus continues to predominantly affect young persons, with 60% of the confirmed cases being detected in persons less than 20 years of age, in 7 selected countries of the Region. In spite of limitations to the availability of data, the percentage of deaths with underlying conditions in Argentina, Chile, and Mexico, is between 53 and 59%. Argentina and El Salvador report having very high intensity of respiratory illness; and, in the case of El Salvador, an increasing trend of disease and a severe impact on health-care services during the same time period.
• Australia: As of August 4, 2009, Australia has 23,692 confirmed cases (1,583 new cases in the past 24 hrs) and 70 deaths. There are currently 419 people in hospital across Australia with Pandemic (H1N1) 2009, and 115 (27%) of these are in intensive care units. The total number of hospitalizations in Australia since the Pandemic (H1N1) 2009 influenza was identified is 2,705.
• New Zealand: As of August 4, 2009, the total number of confirmed cases in New Zealand is 2,872 (up 17 cases in the past 24 hrs), and 14 deaths where Pandemic (H1N1) 2009 was a primary cause of death. Currently, 52 people are reported to be in hospital with Pandemic (H1N1) 2009 or its complications, including 20 in the ICU. The data from ESR's sentinel general practice surveillance system shows weekly influenza-like illness (ILI) consultation rates nearly three times higher than the winter peak experienced in the last two years.
• Argentina: Between epidemiological weeks 20 and 30, 762,711 cases of ILI were reported. From epi week 27 (5-11 July), a downward trend in the number of cases is observed in 18 of 24 provinces, however ILI activity still exceeds the seasonal epidemic threshold. There have been 5,710 laboratory-confirmed cases of Pandemic (H1N1) 2009, 6,384 cases of severe acute respiratory infection requiring hospitalization (most in children under 5 years old and 15-24 years old), and 337 Pandemic (H1N1) 2009-associated deaths reported (the most affected age group is those 50-59 years of age, and 47% of cases had a history of chronic illness or other risk factors for disease).
• Chile: As of July 28, 2009, the number of laboratory-confirmed cases in Chile is 11,860, with 328,173 cases compatible with the case definition. 1,022 confirmed cases have required hospitalization. There have been 96 deaths with laboratory-confirmed Pandemic (H1N1) 2009, and of these 87 have been classified as influenza-associated. Of these, 58.6% were male with a median age of 47 years, and 60% had underlying illness. Prior to epi week 20, RSV, parainfluenza and adenovirus were predominant. RSV continues to be the predominant pathogen detected in children < 1 years of age.
• South Africa: As of July 31, 2009, South Africa reported a total of 591 laboratory-confirmed cases and one death from Pandemic (H1N1) 2009. For epi week 29, ending June 19, 84% of influenza isolates from all surveillance sources were A(H3N2) and 10% were Pandemic (H1N1) 2009.
  • NICD <http://www.nicd.ac.za/>

Northern Hemisphere

• United States: As of July 31, 2009, the CDC reports 5,514 hospitalized cases, and 353 deaths due to Pandemic (H1N1) 2009 in 47 reporting States and Territories. During week 29 (July 19-25, 2009) influenza activity decreased in the United States; however, there were still higher levels of influenza-like illness than is normal for this time of year. 16.1% of specimens reported to CDC were positive for influenza, and over 98% of all subtyped influenza A viruses were Pandemic (H1N1) 2009.
• Europe: As of August 5, 2009, European countries reported 1,016 new cases in the previous 24 hours for a total number of cases of Pandemic (H1N1) 2009 in EU and EFTA countries of 28,908 including 42 deaths.
• United Kingdom: The cumulative number of deaths reported due to Pandemic (H1N1) 2009 in the UK is 31. On July28, there were 793 inpatients in hospitals in England with suspected Pandemic (H1N1) 2009, of which 268 were newly hospitalized in the previous 24 hours. The highest hospitalization rate has consistently been in the under 5-year group. Hospitalization rates have remained stable over the past two weeks. HPA estimates that there were 110,000 new cases in England last week (range 60,000 - 160,000). There has been a decrease in the estimated number of cases in 5-14 year olds. Estimated cases have continued to increase in other age-groups and in the North.

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FluWatch reports include data and information from five main sources: laboratory reports of positive influenza tests in Canada; sentinel physician reporting of influenza-like illness (ILI); provincial/territorial assessment of influenza activity based on various indicators, including laboratory surveillance, ILI reporting, school and work site absenteeism, and outbreaks; influenza-associated pediatric hospitalizations; WHO and other international reports of influenza activity.
The map shows influenza activity in the “influenza surveillance regions” † within each jurisdiction, as determined by the provincial/territorial epidemiologists.

Abbreviations: Newfoundland/Labrador (NL), Prince Edward Island (PE), New Brunswick (NB), Nova Scotia (NS), Quebec (QC), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), British Columbia (BC), Yukon (YT), Northwest Territories (NT), Nunavut (NU).

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Definitions for the 2008-2009 season