The swine flu situation in Sweden mid November 2009

Today, 12 November 2009, the Swedish Institute for Infectious Disease Control (SMI [Swedish abbreviation]) released an update on the current situation with the A(H1N1) in the country.

According to the press release:

The activities of the new flu A(H1N1) continued to rise during week 45 [Nov. 2-8] and the number of cases verified by laboratories doubled again. During week 45, 1233 new cases of the new flu were reported to the SMI compared to 776 from week 44.

Almost all counties reported an increased number of cases compared to week 44. In total, 4133 cases of the new flu verified in laboratories have been reported in Sweden. In particular the reports have increased for children between the ages of 0-4 years. The number of cases in proportion to the population remained the highest in the county of Norrland. The spreading of the flu was less in the south eastern part of Sweden. The SMI estimates that 150 000 to 390 000 people have had the new flu in Sweden since week 38 [Oct. 14-20].

Medical treatment has been reported for 74 patients during week 45 with the below age distribution:
• Under 5 years: 18 people
• 5-14 years: 7 persons
• 15-39 years: 30 persons
• 40-65 years: 15 persons
• Over 65 years: 4 persons

According to estimates made by the SMI, the number of people in hospital are probably more than what have been reported.

The full report provides detail analysis and an official overview of the swine flu situation in Sweden during the first week of November 2009. It also provides a summary of the situation in other countries. You can read the full report under “Read More”

The original article, in Swedish, can be found here

Flu report, week 45 (Nov. 2-8), 2009

Report on the current influenza status

The flu activity has increased and the number of cases has doubled again

The activity of the flu continued to increase during week 45 and the number of cases verified in laboratories doubled again. Primarily, the number of reports have increased for children between the ages of 0-4 years. The number of cases in proportion to the population continued to be the highest in the county of Norrland, but almost all other counties reported more cases then during week 44. We believe that 150 000 to 390 000 people have so far fallen ill with the flu. The number of people hospitalized has also increased but to a smaller degree, partially due to inadequate reporting. Two new death cases associated to the new flu have come to our attention during week 45.

Norway is 2-3 weeks ahead of Sweden in the epidemic and they had 4 times as many cases verified in laboratories (calculated on the number of inhabitants) during week 45. Using this as a basis, we have not yet reached the top levels of the epidemic, except possibly in some counties in Norrland. Internationally, there is still a rising flu activity all around the northern hemisphere. Our Nordic neighbors reported increased activities and in Norway and Finland 8 000 and 2 300 cases respectively have been confirmed, and this has put a heavy strain on the healthcare services. Canada reported one case of resistance to Oseltamivir in connection to a post exposition prophylaxis.

The new flu A(H1N1) in Sweden

In total, 4133 cases of flu, verified in laboratories, have been reported in Sweden. 1233 cases were reported during week 45 which can be compared to 776 cases during week 44. All counties except Kalmar reported more cases during week 45 than week 44. Six counties in the south eastern part of Sweden along with two counties in the mid-section of Sweden did not seem to have been reached by the flu-wave during week 45 based on laboratory results. Contacts with the SMI confirms that this is pretty much the case and is not due to different testing practices in different counties.

Norway had 2500 cases of the flu, verified in laboratories during week 45. They had four times as many incidents than Sweden, based on their population, and they still are not sure that they have reached the peak of the epidemic. They calculate that a minimum of about 600 000 people have come down with the disease (which would translate to 150 000 people in Sweden up to week 45 – that is our minimum number). That is, approximately thirteen percent of Norway’s population which is more than the twelve percent that are assumed to have fallen sick in New Zealand during the outbreak there. This indicates that at least some countries in the northern hemisphere can have more cases than what was reported in the southern hemisphere. This is not strange considering that the virus has had many months to slowly spread amongst the population before the climate and possibly other circumstances gave it the possibility to spread explosively. The outbreak in the southern hemisphere occurred around the time when the virus first surfaced.

Hospital care has been reported for 74 patients compared to 62 people during week 44. Eighteen of these were children under the age of five, seven are between 5-14, thirty were between 15-39 and approximately fifteen were between 40-65. The number of hospitalized persons is surely more than what has been reported and we can not provide new numbers with regard to those in intensive care. A new system for reporting cases of intensive care will come into effect at the National Boart next week, and we hope to have more accurate numbers then.

Two patients have been reported to have passed away due to ongoing flu infection. Both were upper middle-aged men. Until now, all people who have passed away due to the flu in Sweden were male and, with the exception of the child who passed away at Astrid Lindgrens child hospital, they were all between 40 and 60 years old. The number of positive tests in the surveillance testing was down to thirty four this week.

The preliminary data from the population based surveillance in Stockholm and data from the sentinel testing estimates that 150 000 to 390 000 people in the country has had the flu since week 38. The numbers are based on a number of assumptions and should be seen as rough estimates.

Even if we do see an increase in basically all systems of reporting, the increase is by far the greatest in the cases verified in laboratories. Sentinel reporting, which has just now come into full effect, reports that the proportion of those seeking aid in the healthcare system compared to those with other symptoms, is similar to the levels we see when the seasonal flues reach their peaks. On the other hand, the number of cases verified in laboratories is way higher then what we have ever witnessed. It seems that, in comparison to the seasonal flu, a disproportionately large number of the positive tests are coming from people who are not hospitalized. This comparatively large number of reports must be due to a sharp increase in the tendency to take tests.

The vaccine against the new flu contains the protein (Haemagglutinin) from the flu strain A/California/7/2009. The vaccine is killed and contains only a part of the virus itself. Since the vaccination is occurring at the same time as the flu is spreading, there is always the risk of being infected a couple of days before or after receiving inoculation. Unfortunately, that means that, in these situations, the body does not have enough time to develop an antibody protection. The SMI has received tests from three patients where the disease has broken out three or four days after they received their vaccination. We have characterized the flu strains from the three patients. They are similar to the ones circulating in Sweden. The dendogram below shows that all circulating strains of the flu are very similar to the vaccine.

Denodogram for the H1 tree

Most people have developed some form of protection after two weeks and three weeks after vaccination, most people, have a proper protection (the exception are children under 13 years of age and those with suppressed immune systems who need two doses).

During an outbreak at a day-care center, 14-16 children came down with the flu this week. The two kids who did not get the flu had both received their vaccination. This is a first indication that the vaccine has a good protection level.

 

Figure 1. The number of reported cases of A(H1N1) and seasonal flu from week 20, 2009-2009

Image linked from smittskyddsinstitutet.se

Week 34 35 36 37 38 39 40 41 42 43 44 45
Positive samples (%) 10% 13% 6% 4% 5% 4% 3% 9% 15% 26% 33% 37%
Analyzed tests 977 1349 2722 2848 1838 1340 997 1027 1154 1574 1956 3709

 

Table 1. Cases in Sweden distributed over county councils

County council Number of cases Number per 100 000 people
Blekinge 24 15,8
Dalarna 60 21,8
Gotland 12 21,0
Gävleborg 141 51,1
Halland 56 19,1
Jämtland 67 52,9
Jönköping 24 7,2
Kalmar 28 12,0
Kronoberg 45 24,7
Norrbotten 95 38,0
Skåne 475 39,2
Stockholm 1470 74,3
Södermanland 75 28,1
Uppsala 153 46,8
Värmland 73 26,7
Västerbotten 350 135,8
Västernorrland 267 97,4
Västmanland 38 15,2
Västra Götaland 554 35,6
Örebro 80 28,8
Östergotland 76 18,0
Sweden 4133 44,7

 

Figure 2. Map over the number of cases per 100 000 people for week 45

The color of the county shows the incidents as laboratory diagnosis per 100 000 inhabitants for the reporting week. The number in the county displays the total number of cases for the complete season. The small diagrams in each county show the development of the epidemic in the county week by week.

Image linked from smittskyddsinstitutet.se

 

Figure 3. Age distribution of reported cases of A(H1N1)

Image linked from smittskyddsinstitutet.se

 

Figure 4. Sentinel reporting

Reported flu-like symptoms (ILS) 2006-2009
Image linked from smittskyddsinstitutet.se
The diagram shows the percentage of patients with clinical flu-like symptoms (ILS) of the total number of patient visits.

Week 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Number of people 4 5 2 3 5 8 14 8 10 25 18 21 65 41 35 37 20 21 34 45 76 107

 

Figure 5. Sentinel testing

We have analyzed 184 tests during week 45 as a part of the sentinel testing project. Three PCR analysis is carried out on each sample, so this week we carried out 552 analysis which is a new record. We have identified the new flu in samples sent in from across the country, from the north to the south. Most of the positive tests are taken in the Stockholm region, Västerbotten and the county of Kronoberg.

Image linked from smittskyddsinstitutet.se

 

Number of reports from the sentinel reporting and sample takings

We are since week 40 following the WHO’s norms and use the notation A/pH1 for the pandemic new flu in the table below.

Sentinel system Sentinel testing** weeks 27-45
County councils Number of patients with ILS* % of all patient visits Total number of received samples Total flu A Total flu B Total A/pH1 cumulatively Total A/H1 cumulatively Total A/H3 cumulatively
Blekinge 0(3) 0 6(18) 4(5) 0(0) (5) (0) (0)
Dalarna 9(71) 2,61 13(109) 0(4) 0(0) (4) (0) (0)
Gotland 0(0) 0 5(72) 0(1) 0(0) (3) (0) (0)
Gävleborg 3(25) 1,27 0(0) 0(0) 0(0) (0) (0) (0)
Halland 4(14) 0,81 2(26) 1(2) 0(0) (2) (0) (1)
Jämtland 7(21) 2,02 4(41) 1(6) 0(0) (6) (0) (0)
Jönköping -(0) 5(34) 1(4) 0(0) (4) (0) (0)
Kalmar 4(25) 0,32 4(10) 0(1) 0(0) (1) (0) (0)
Kronoberg 0(5) 0 1(15) 0(1) 0(0) (1) (0) (0)
Norrbotten 2(23) 2,74 10(32) 7(10) 0(0) (10) (0) (0)
Skåne 8(76) 2,42 6(39) 3(3) 0(0) (3) (0) (0)
Stockholm 12(54) 1,68 69(511) 23(120) 0(0) (117) (0) (0)
Södermanland 2(7) 10 0(0) 0(0) 0(0) (0) (0) (0)
Uppsala 1(20) 0,83 17(134) 4(16) 0(0) (15) (0) (0)
Värmland 3(5) 4,17 0(0) 0(0) 0(0) (0) (0) (0)
Västerbotten 23(75) 3,65 20(220) 10(82) 0(0) (82) (0) (0)
Västernorrland 2(4) 2,53 9(101) 3(41) 0(0) (39) (0) (0)
Västmanland 4(41) 1,15 5(36) 1(6) 0(0) (6) (0) (0)
V. Götaland 20(124) 0,51 6(39) 3(7) 0(0) (7) (0) (0)
Örebro -(0) 2(4) 1(2) 0(0) (2) (0) (0)
Östergötland 3(15) 0,61 0(0) (0) (0) (0)
Total 107(608) 1,11 184(1441) 62(311) (0) (307) (0) (1)

* Number of flu diagnosis during the current week of reporting.
Numbers in parenthesis indicate the cumulative cases from week 20 2009.

 

Notifications from laboratory reporting

Below is new table for laboratory reporting that shows the number of flu cases reported since week 20, both for A(H1N1) and the seasonal flues A and B.
* The number of flu diagnoses during the reported week. The number in parentheses cumulatively specifies cases from week 20, 2009.

County Lab Cases of A(H1N1)* Cases of flu A* Cases of flu B* Total A(H1N1), A and B* for current week Total A(H1N1), A and B* (from week 20,2009)
Blekinge Karlskr 0(0) 0(0) 0(1) (1)
Dalarna

Falun 16(30) 0(4) 0(0) 16 (34)
Gotland Visby 0(0) 0(0) 0(0) (0)
Gävleborg Gävle (115) 0(4) 0(0) 35 (119)
Halland Halm 33(52) 0(10) 0(2) 33 (64)
Jämtland Östers 36(52) 0(0) 0(0) 36 (52)
Jönköping Jönk 2(21) 0(0) 0(0) 2 (21)
Kalmar Kalm 5(18) 0(2) 0(0) 5 (20)
Kronoberg Växjö 20(61) 0(11) 0(0) 20 (72)
Norrbotten Luleå 2(8) 0(0) 0(0) 2 (8)
Gällivare 0(0) 0(0) 0(0) (0)
Skåne Malm 158(486) 0(3) 0(1) 158 (490)
Kristian 0(0) 0(0) 0(0) (0)
Lund 0(0) 0(0) 0(0) (0)
Helsing 0(0) 0(0) 0(0) (0)
Stockholm Hudd 47(387) 0(19) 0(3) 47 (409)
Solna 250(889) 2(18) 0(11) 253 (918)
SMI 50(325) 0(0) 0(0) 50 (325)
Södermanland Eskils* 0(1) 0(5) 0(0) (6)
Uppsala Upps 62(209) 0(19) 0(0) 62 (228)
Värmland Karls 29(67) 0(1) 0(0) 29 (68)
Västerbotten Umeå 95(368) 1(14) 0(8) 96 (390)
Västernorrland Sunds 53(179) 0(0) 0(0) 53 (179)

Västmanland

Väste 0(0) 0(0) 0(0) (0)
V. Götaland Götb 131(407) 3(21) 0(12) 134 (440)
Udde 0(1) 0(0) 0(0) (1)
Skövd 135(500) 1(6) 0(0) 136 (306)
Borås 8(8) 0(0) 0(0) 8 (8)
Örebro Örebr 45(78) 0(9) 0(0) 45 (87)
Östergötland Link 21(55) 0(7) 0(0) 21 (62)
Unknown 0(16) 16)
Total Total 1233(4133) 7(153) 0(38) 1241 (4324)

 

New surveillance project

Flu surveillance based on anonymous data searches carried out on the homepage vårdguiden.se.
Since the flu A(H1N1) produces symptoms that do not require medical attention for the vast majority of people, it is important to measure sickness amongst those who do not visit a doctor. The SMI’s homepage presents charts every week on last weeks data searches.

Link to the search tool

Sickness reporting
The sickness report is a surveillance system for measuring flu sickness amongst the population in the county of Stockholm where approximately 5500 persons report through a homepage or a phone message service when they become sick.
Link to the sickness reportings news letter
Link to the sick reportings news archive

 

The new flu A (H1N1) in the rest of the world

Norway
Norway has observed a continued growth of incidents in the entire country. There have been over 8000 confirmed cases of the flu A(H1N1), out of which 1700 tested positive during week 44. Just over 50% of those who were tested are positive for the new flu, which is a definite increase since previous measurements. The occurrence of flu like symptoms amongst those seeking medical attention is approximately 10%. Since the first of September, there have been about 500 cases of hospitalizations due to the new flu and out of those about 70 were treated in intensive care units. The age distribution amongst the 16 fatal cases have been similar to those seen in other countries; a majority of the people had underlying diseases and only two did not belong to any risk categories:

5 persons under 20 years old
5 persons 20 – 40 years old
4 persons 40 – 60 years old
2 persons > 60 years old

7 female
5 male
1 teenager
3 children

Finland
Also Finland has a observed a clear trend of continued spreading of the virus and 2593 cases of the flu A(H1N1) have been confirmed so far. One, 68 year old patient who was suffering from long term chronic disease passed away on Friday, 6th of November 2009 in the Northern Österbotten district and is thus the seventh victim in the country.

Denmark
The flu activities in Denmark has increased especially amongst children and the regional hospital in Viborg has taken in several children for observation. No deaths have been reported so far.

The Ukraine
The healthcare authorities have informed that 530 00 people have received care in hospitals due to flu-related symptoms and that the number of deceased has reached 174 people. Of those treated in hospital, the number in intensive care has dropped somewhat to approximately 330 people. 67 confirmed cases of death have been reported and 14 of the deceased were positive with H1N1. The Ukraine has a population of 48 million people.

Most countries in the northern hemisphere report a continued upward moving trend.

Virology
The pandemic flu A(H1N1) continues to be the dominant flu virus responsible for about 75% of all flu tests taken across the world which is an increase compared to earlier weeks.

Canadian doctors describe Oseltamivir resistance in a man that had prophylactic treatment since his son was confirmed to have A(H1N1). The doctors report was published in the New England Journal of Medicin and they propose limitations of the indicators for post exposure prophylaxis and that in these cases, two doses is provided every day instead of one. Read the article here

The ECDC has published a compilation of available data to support planing for healthcare services.
– Clinical attack rates: up to 20% (5-20%)
– Fatality: up to 3 per 100 000 inhabitants
– Number of hospitalized people: up to 100 per 100 000 inhabitants
– Sick-leave: no larger difference to a more difficult flu season.

Read the entire compilation here

Statistics from other sources

Flu calls to 1177 Healthcare-assistance
Presented below are statistics from phone calls about flu-like symptoms made to the county councils phone advisory service 1177 Healthcare-assistance. The statistics are based on the reasons why nurses in the various advisory units were contacted. Only one reason for the contact can be provided. If a person describes several symptoms, the main symptom is registered as the primary reason for the contact.

Seven reasons for contact have been selected as reasons that can be attributed to the flu. These are presented in the chart below for the period between week 34-45, 2009.
Image linked from smittskyddsinstitutet.se
[Translation of the legend (top to bottom)
Breathing difficulties – children
Breathing difficulties – adults
Fever – children
Fever – adults
Cough – children
Cough – adults
Throat ache]

The following county councils are included in the statistics:
Gotlands Kommun
Jämtlands läns landsting
Landstinget Blekinge
Landstinget Dalarna
Landstinget Gävleborg
Landstinget Halland
Landstinget Kronoberg
Landstinget i Kalmar län
Landstinget i Uppsala län
Landstinget i Västmanland
Landstinget i Östergötland
Region Skåne
Västra Götalandsregionen
Örebro läns landsting

More information about 1177 can be found on their homepeage: www.1177.se

Flu surveillance in the county councils

Seasonal flu in Sweden

During week 45, 7 cases of the seasonal flu A have been reported through voluntary laboratory reportings.

Collection of links

Please visit the last section of the original document for the complete link reference:
Original article