A summary of confirmed H1N1 cases to date

A summary of confirmed H1N1 cases to date

The data, as of this posting:

4694 cases of influenza A (H1N1) infection reported in 30 countries.

Confirmed deaths in Mexico attributed to H1N1 infection: 48.

Confirmed cases of H1N1 influenza in US: 2532.

Confirmed deaths in US attributed to H1N1 infection: 3.

Confirmed cases of H1N1 influenza in Canada:  284.

Confirmed deaths in Canada attributed to H1N1 infection: 1.

Confirmed cases of H1N1 influenza in Spain:  95.

The temptation at this point is to assume that the threat of H1N1 is over, and our limited attention span should now be focussed somewhere else.  From my vantage point, the following seems clear:

1) This H1N1 strain, at least in the currently circulating form, appears to produce symptoms comparable to seasonal influenza strains.  For now, the fears that we were dealing with a particularly virulent strain of influenza have not materialized.

2) The number of cases will continue to rise, as will the number of deaths.  But neither cases nor deaths appear to be rising as rapidly as initially feared.  The graphs below show the incidence rates (per 1000) associated with the 1918 pandemic and with the current H1N1 outbreak.  The  contrast between these graphs should be noted (note the dramatic difference in Y-axis values).

Incidence rates/1000, US, 1918 Influenza Pandemic
Incidence rates/1000, US, 1918 Influenza Pandemic

Incidence rates/1000, current H1N1 outbreak
Incidence rates/1000, current H1N1 outbreak

3)The apparent waning of this H1N1 outbreak is good news, but novel strains of this sort do not simply disappear into the ether.  At this stage, the fate of this strain in the Southern Hemisphere, where the influenza season is just beginning, bears keeping an eye on.  Similarly, many epidemic strains will resurface, often in a more distinctive and aggressive form, in a second wave of infection.  This ain’t over yet.