Saturday, January 06, 2018

Canada FluWatch Week 52 & Diminished Vaccine Expectations


Given the level of flu activity we're seeing the continental United States (see CDC FluView Week 52: Influenza `Increased Sharply' Across The Nation) it isn't terribly surprising to see flu on the rise in Canada as well.
As the map above illustrates, Influenza A H3N2 is dominating, although influenza B is making an early and unusually strong appearance.
The summary from a much longer, and more detailed FluWatch update follow:

FluWatch report: December 17, 2017 to December 30, 2017 (weeks 51 & 52)

Overall Summary
Overall, influenza activity continues to increase across Canada. All indicators of influenza activity increased in weeks 51 and 52, but are within the range of expected levels for this time of year.

The majority of influenza detections continue to be A(H3N2), although the proportion of detections that are influenza B has been increasing steadily. 

Influenza B is circulating much earlier than usual this season.The number of influenza B detections remains substantially greater this season compared to previous years.

To date this season, the majority of lab confirmations, hospitalizations and deaths have been among adults 65 years of age and older.

For more information on the flu, see our Flu(influenza) web page.
         (Continue . . . )

Making flu headlines this morning in Canada is the following (not exactly news breaking) report from CBC News:

Flu vaccine may have low effectiveness against dominant strain, Canada's top public health doctor says

H3N2, associated with more severe illness among children and elderly, causing majority of flu cases

By Nicole Ireland, CBC News Posted: Jan 06, 2018 6:01 AM ET Last Updated: Jan 06, 2018 6:01 AM ET 

Canada's chief public health officer says it's possible that this year's flu vaccine may have limited effectiveness against a particularly severe strain of influenza A that appears to be dominant throughout Canada.  

"In Canada it's still too early to actually tell how effective this vaccine will be," Dr. Theresa Tam told CBC News. "There is a potential ... of low vaccine effectiveness, but we really can't tell at this point in time."
        (Continue .  . . )

While Dr.Tam is still offering some hope for this year's jab, for months we've seen mounting evidence suggesting this year's H3N2 component (and the Influenza B strain included in the trivalent vaccine) were going to under perform this winter.

Just yesterday the BMJ published:

Trivalent flu vaccine won’t protect against influenza B strain predominantly circulating 
BMJ 2018; 360 doi: (Published 05 January 2018)
Public Health England has warned that the trivalent flu vaccine most commonly administered in general practice will not protect against the strain of influenza B that appears to be predominately circulating this year. The latest figures show influenza is circulating at higher than seasonally expected levels, with increases in GP consultations and emergency department attendance.

If you were lucky enough to get the quadrivalent vaccine - which isn't as common in Europe as it is in the United States - you will likely fare far better against Influenza B this winter. 

Going back even further, more than 3 months ago we saw ECDC: H3N2 Flu Vaccine Component Likely `Suboptimal', while a week prior to that, in WHO recommendations for influenza virus vaccine composition for the 2018 southern hemisphere influenza season, the decision was made to change out both the H3N2 and the influenza B component in next year's trivalent Flu vaccine.
And just before Christmas,  the ECDC: Rapid Risk Assessment For Seasonal Flu EU/EEA 2017-18, stated the following:
• Vaccine effectiveness against A(H1N1)pdm09 is expected to be high, whereas effectiveness against A(H3N2), the most prevalent type A virus, is likely to be low.
B/Yamagata viruses are dominant so far, and vaccine effectiveness against this virus will be low as it is not included in the most widely used trivalent vaccine. Some effectiveness could be expected from cross-protection as a result of vaccination against B/Victoria virus.
Other vaccine effectiveness (VE) reports this fall include:
Eurosurveillance: Low H3N2 Vaccine Effectiveness In Australia's 2017 Flu Season
PLoS Path.: A Structural Explanation For The Low VE Of Recent H3N2 Vaccines
Eurosurveillance: Low 2016/17 Vaccine Effectiveness (VE) Among Elderly Hospitalized H3N2 Cases

While I get the flu vaccine every year, and urge others to do the same, I do so with the understanding that the flu vaccine is far from perfect, and some years it is less perfect than others.
Even in years when its effectiveness is diminished, there is some evidence that it may reduce the severity of illness (see CID Journal: Flu Vaccine Reduces Severe Outcomes in Hospitalized Patients).

Like wearing a seat belt in a car crash, getting the vaccine doesn't guarantee you'll come away unscathed . . .  but does it improve your chances.

There is an understandable reluctance among many public health officials to `talk down' the flu vaccine - even when evidence suggests its effectiveness may be less than expected - out of fears that may dissuade some people from getting a potentially life-saving jab.
I understand it, but I also worry it is a mistake.
If you oversell the protective qualities of the flu vaccine, you may get higher uptake of the vaccine, but you may also convince people who get the jab that they are more `protected' than they really are, and they will take fewer `flu hygiene' precautions during flu season.

You also risk alienating people who get the vaccine this year - get sick as a dog anyway - and who decide it isn't worth getting next year.
It's no secret we need a better flu vaccine, and while we've seen some progress with high dose, adjuvanted, and quadrivalent vaccines the past few years, many of the deficits outlined in 2012's CIDRAP: The Need For `Game Changing’ Flu Vaccines remain.  
Science in general, and `Big Pharma' in particular, are walking a very narrow tightrope when it comes to the public's faith in them (see PEW Research Mixed Messages about Public Trust in Science).  The Dengvaxia fiasco in the Philippines is just the latest hit they have taken.

While I have hopes this year's vaccine will afford me some degree of protection, now is not the time to be making promises this year's vaccine is unlikely to keep.

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