PEI Influenza Summary 2017-2018 Season

Summary

  • Influenza B accounted for 53% of all lab-confirmed cases in PEI in 2017-18.
  • Our seasonal total was 319 lab-confirmed cases (9 A/pH1N1, 136 A/H3, 4 A/unsubtyped, 170 B).
  • The median age of cases was 62 years with 59% being female.
  • In total there were 132 hospitalizations, including 13 ICU patients.

 

Epidemiological curve of laboratory data

Sporadic influenza activity in PEI started in mid-October, and activity continued throughout the season. Influenza A accounted for 47% of all lab-confirmed cases in PEI, while influenza B made up the remaining 53% of lab-confirmed cases. Flu activity peaked in late January, and overall, the 2017-18 season saw greater than average flu activity. The median age of cases was 62 years and ages ranged from <1 to 99 years. Overall, 59% of all lab-confirmed cases were diagnosed in females. Flu activity ended in May, but sporadic cases of influenza may occur at any time during the year.

Graph of lab-confirmed flu cases for PEI for the 2017-2018 Influenza season.

*Lab-confirmed influenza tests are just an indication of greater influenza activity as many individuals with influenza do not seek medical attention.

 

Positive influenza test results, cumulative 2017-18 season

Influenza A/H3 accounted for 43% of all lab-confirmed cases in PEI in 2017-18. There were more lab-confirmed Influenza B cases (53%) than Influenza A during the 2017-18 season in PEI.

Lab-confirmed cases

Cumulative 2017-18

Influenza A

149

A/pH1N1

9

A/H3

136

A/unsubtyped

4

Influenza B

170

Total Influenza

319

 

Respiratory outbreaks, cumulative 2017-18 season

There were 18 respiratory outbreaks reported to the Chief Public Health Office. Of the outbreaks, 11 were Influenza B, six were Influenza A/unsubtyped, and one was influenza-like illness (ILI). The outbreaks occurred in October, December, January, February, March, and April.

Respiratory Outbreaks

Cumulative 2017-18

Influenza A

6

A/pH1N1

0

A/H3

0

A/unsubtyped

6

Influenza B

11

Influenza-like Illness

1

Other Respiratory

0

Total Outbreaks

18

Outbreaks are defined based on the Fluwatch definitions.

 

Severe outcome surveillance

Hospitalization data is gathered through infection prevention and control practitioners at each Island hospital. There were 132 hospitalizations, which included 13 ICU cases during the 2017-18 influenza season. The median age of hospitalized patients was 77 years (mean: 67 years), and the range was <1 to 99 years. Hospitalized patients were more likely to be female (58%).
The average length of stay for hospitalized patients was 11 days (median: 6 days), and the range was 1 to 83 days. There was chronic disease information for 128 cases. Of these, approximately 80% had at least one chronic condition.

Deaths are only reported when there is a positive influenza laboratory test. However, influenza may not have been the major contributing cause of death.

Severe Outcome

Cumulative 2017-18

Hospitalizations

132

ICU

13

Deaths

6

 

Historical influenza seasons

The predominant strain of circulating influenza changes year-to-year. The strain of influenza can impact the severity of disease, the age group(s) affected, and the number of individuals presenting themselves to the health system for care. In addition, the request for influenza testing varies season-to-season.

Influenza Season

Predominant Strain

All Cases*

Hospitalized**

ICU

2011-12

B

53

11

0

2012-13

A/H3

124

54

6

2013-14

A/pH1N1

119

62

13

2014-15

A/H3 (B)

209

98

11

2015-16

A/pH1N1

71

39

2

2016-17

A/H3

208

88

11

2017-18

B

319

132

13

*Laboratory confirmed cases. Note that clinical diagnosis of influenza takes place frequently in the community during peak season and is not confirmed with laboratory testing.

**Hospitalized counts include those admitted to ICU.

 

Published date: 
June 18, 2018
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