While the second wave of H1N1 human swine flu cases in Manitoba peaked last fall - and was far less serious than many forecasts originally predicted - and seasonal flu has yet to appear at all, the BRHA is still urging residents to get their flu shots if they haven't already done so.
"Manitobans are still getting sick from the Pandemic H1N1 flu,"Dr. Lisa Richards, medical officer of health for the Burntwood and Churchill regional health authorities, said in a Feb. 17 paid advertisement in the Thompson Citizen. When pressed on the point recently, Richards said, "We have had very few lab confirmed cases of H1N1 in the province since late December, and as far as we can detect, seasonal flu has not yet appeared in the province."
In fact, that's the case all across North America: Flu season has been a complete fizzle since shortly after the new year at the latest. Cases of second wave H1N1 infections had peaked by late October in most of North America - at exactly the time the an H1N1 vaccine was made available in Canada and the BRHA rolled out their first flu clinics - and disappeared almost by Christmas.
According to statistics from the Public Health Agency of Canada, visits to doctors by patients with flu-like symptoms spiked in late October, peaking by Halloween and were largely non-existent by late December.
Northern Manitoba was most visibly hit hard by the H1N1 human swine flu pandemic, which began in Mexico a year ago, during the first wave, especially between mid-May and mid-June of last year, when cases swept through isolated First Nations communities in the southernmost part of the BRHA's catchment area; communities such as St. Theresa Point First Nation, with a federal nursing station and First Nations Inuit Health (FNIH) with primary health care responsibility.
At that time there was no vaccine against H1N1 and by July 15 Canada had an H1N1 infection rate of about 20 per 100,000, then the highest in the world. The figure jumped to an astonishing 135 per 100,000 in Manitoba First Nations. As of July 15, 2009, there had been 51 laboratory-confirmed cases of H1N1 amongst First Nations, nationwide. Of the 151 cases, 139 were from Manitoba. Of those 139 cases, 125 were from Manitoba Keewatinook Ininew Okimowin (MKO) First Nations communities.
And then the first wave ended. Just like that.
Manitoba Health says the second wave of H1N1 began Oct. 6. Manitoba reported a total of 1,246 lab-confirmed cases between Oct. 6 and Nov. 23 last year. Of all lab-confirmed cases, 50 per cent - or 617 cases - were children under the age of 18. Another 49 per cent - or 610 cases -- were adults aged 18 to 64. Fifty-two per cent were women and 48 per cent were men.
Between Oct. 6 and Nov. 23, there were six people in intensive care units ICU in Manitoba, five with lab-confirmed cases of H1N1. There were 43 people with lab-confirmed cases of H1N1 hospitalized in ICU during the first wave.
Two commonalities between the first and second wave H1N1 human swine flu infections in Manitoba was patients with confirmed cases were younger than typically found with seasonal flu and a small percentage became gravelly ill with deep lung infections that sometimes required weeks and weeks on special ventilators to save their lives.
By Dec. 1, Manitoba Health reported 34,711 people in the Burntwood Regional Health Authority - more than 74 per cent of the region's population - had been vaccinated against H1N1, while more than 48,000 people living on First Nations - an average of 57 per cent - had been vaccinated against H1N1. Still, overall less than 30 per cent of Manitobans had been vaccinated as of Dec. 1, 2009.
Manitoba Health also said as of last Nov. 28 there had been 14 serious "adverse events following immunization," which have been reported to the Public Health Agency of Canada. "Ten of the serious adverse events have been classified as anaphylaxis, an immediate allergic reaction to the vaccine. There have been no reports of ongoing effects related to these 10 adverse events. None of the reported serious adverse events following immunization in Manitoba have been Guillain-Barré syndrome. A total of 287 adverse events have been reported including a range of reactions at the injection site, coughing, headache, fatigue, feeling unwell or fainting. It is important to note these adverse events have followed immunization but may not necessarily have been caused by immunization. Serious adverse events are investigated to determine the cause."
By Dec. 7, Manitoba Health had reported the "third death associated with lab-confirmed H1N1 in the second wave of the virus." A fourth death was reported Jan. 7. There were seven deaths in the first wave associated with lab-confirmed H1N1."
Between Dec. 8 and 14, no Manitobans with a positive H1N1 lab test or symptoms of a severe respiratory illness were admitted to an intensive care unit," Manitoba Health reported. "Sixteen Manitobans with a positive lab test for H1N1 have been admitted to ICU since the second wave began. Of these, more than three-quarters were aged 18 to 64. One-third of all Manitobans admitted to ICU had no underlying conditions.
On Dec. 23, Manitoba Health reported a case of oseltamivir antiviral resistance in a child under the age of 18 who was being treated for lab-confirmed H1N1. Oseltamivir, also known by the trade name Tamiflu, is an antiviral drug commonly used to treat people infected with influenza. It was the first case of antiviral resistance related to H1N1 flu reported in Manitoba and the eighth in Canada.
That was the bad news. The good was the second wave was about to recede - quickly. "Since Christmas, the Cadham Provincial Laboratory has reported 27 positive H1N1 tests to Manitoba Health including six new cases over the last week," Manitoba Health said Jan. 14. "Since the second wave of H1N1 flu began on Oct. 6, the lab has reported a total of 1,773 positive H1N1 tests."
From Jan. 12 to 25, Cadham Provincial Laboratory reported no new positive H1N1 tests to Manitoba Health.By Jan. 14, Manitoba Health could report that after the biggest public health campaign in Canadian history, almost 37 per cent of Manitobans - slightly more than a third - had got an H1N1 flu shot.
On Jan. 28, Manitoba Health said that since the spring it had "reported the deaths of 11 people who had a positive lab test for H1N1. Of these, about one-third were of aboriginal ancestry and one-third were caucasian. About one-third of all individuals reported having a lung disease (including asthma) and another third had no underlying risk factors for severe illness. Of all deaths, four were aged 40 to 49, two were aged 30 to 39, two were 60 or older, one was aged 50 to 59, one was aged 20 to 29 and one was aged six months to three years.
"Twenty-two Manitobans with a positive lab test for H1N1 have been admitted to intensive case units (ICU) since the second wave began, according to reports provided to Manitoba Health. Of these, 18 (81 per cent) were aged 18 to 64, three (13 per cent) were under the age of 18 and one (five per cent) was 65 or older. Two were from First Nations communities. About 40 per cent of the Manitobans admitted to ICU in the second wave reported obesity as an underlying health condition. Other commonly reported conditions included asthma (36 per cent) and diabetes (23 per cent).
"A total of 160 Manitobans have been hospitalized with a positive lab test for H1N1 since the second wave began. Of these, 103 (64 per cent) were aged 18 to 64, 48 (30 per cent) were under the age of 18 and nine (six per cent) were 65 or older."
"The recent national reports of pandemic flu activity mirror our experience here in Manitoba as well," Richards said.
"As you know, though, not detecting the virus by laboratory does not always imply that there is no activity, as finding positive cases by lab is often only the 'tip of the iceberg.'
"I think the more important message that we are trying to portray is that there is still a benefit to receiving the vaccine if you have not already done so. While we are in a period of anticipation of a third wave, it is difficult to predict if and when this may occur. As you may know, influenza season in Manitoba can extend to the spring, so it is possible that we may see an increase in flu cases (H1N1 or seasonal) in the coming months. It is important that as many Manitobans as possible are vaccinated with the H1N1 vaccineto reduce the impact of a third wave (in the event it does occur in the next few months). Receiving seasonal flu vaccine even at this point in time would also be beneficial."
Dr. Michael Gardam, director of infectious disease prevention and control with the Ontario Agency for Health Protection and Promotion, predicted Feb. 23, that there will be no "third wave" because so many people now have antibodies against the virus, although that doesn't explain the absence of seasonal flu viruses, such as H3N2, which is active in China right now.
Dr. Margaret Chan, director-general of the World Health Organization (WHO), recently decided to leave the status of H1N1 as a Phase 6 global pandemic, after a meeting last month of WHO's emergency committee of 15 influenza experts.
Chan noted the "committee was of the view that there was mixed evidence showing declining or low pandemic activity in many countries, but new community level transmission activity in West Africa. Moreover, they expressed concern that the winter months of the Southern Hemisphere had not yet started and there was uncertainty whether additional generalized waves of activity might occur."
