Everyone knows it’s flu season. We see the evidence in birds and people with H5N1. The Indian subcontinent is awash in birds with H5N1. Sometimes here we forget to remind people it is also flu season with the regular circulating subtypes, H1 and H3 and this is shaping up to be a predominantly H1 season in Europe and the US.
In the US:
During week 3 (January 13 – 19, 2008), influenza activity continued to increase in the United States.
Three hundred twenty-nine (11.1%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories were positive for influenza.
The proportion of deaths attributed to pneumonia and influenza was slightly above the epidemic threshold.
The proportion of outpatient visits for influenza-like illness (ILI) was above national baseline levels, and the proportion of outpatient visits for acute respiratory illness (ARI) was below national baseline levels. The East North Central, East South Central, Mountain, New England, Pacific, West North Central, and West South Central regions reported ILI at or above their region-specific baselines.
Six states reported widespread influenza activity; 17 states reported regional influenza activity; 17 states and the District of Columbia reported local influenza activity; 10 states and Puerto Rico reported sporadic influenza activity. (CDC Flu Surveillance site)
Here is how things have shaped up so far this season:
It’s flu season in Europe, too. Most isolates are also H1:
Increased influenza activity was reported in 13 European countries in week 2 of 2008: Austria, Bulgaria, France, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Slovenia, Spain, Switzerland and the UK. Based on historical trends, influenza activity is expected to increase in more countries in the coming weeks and to move gradually eastwards and northwards in Europe . Influenza activity is mainly associated with type A influenza virus, subtype H1, which usually causes only mild- to medium-intensity influenza epidemics. (Eurosurveillance)
It’s clear flu season is well underway. We can expect it to go full tilt at least through March. The same thing will be happening in those areas where H5N1 is endemic in poultry and where sporadic cases of human H5N1 occur. This is something to keep in mind when there are reports of dozens, sometimes hundreds of “suspect” cases appearing in an area where there are one or more H5N1 cases. Those “suspect” cases are happening right now, without any H5N1 anywhere near them. It’s just that no one is paying any attention because it’s flu season.
The good news for seasonal flu is that H1 seasons tend to be less severe in terms of excess mortality than H3 seasons and the predominant strain of H1N1 circulating this year is included in the flu vaccine.
I got a flu vaccination again this year. There remains some controversy about its effectiveness in my age group (65+) but I’m hoping for some antigenic effect. If you are younger than me (and, alas, most people seem to be these days) I’d definitely advise getting a flu shot. It’s not too late and you don’t want to get the flu. Maybe H1N1 or H3N2 aren’t H5N1 but they are bad enough. If you’ve had genuine flu you already know that. If you haven’t, well, I hope you don’t get it.
If it doesn’t kill you it won’t make you stronger, either. Trust me.