Monday, May 11, 2009
Swine Flu, WHO Knew?
The US count is always outdated, but so far the CDC lists 2,532 US confirmed cases. This does not represent a sudden change in incidence, but a change in the ability to test. The CDC sent out test kits to the state labs. Then each state lab was to test 5 cases, and submit those cases to the CDC for confirmation. After that, they were free to run. The result (in less than a week):
Not every state is testing, and not every state is testing the same way, so the case counts should be viewed with that in mind. With a mild flu, most people don't even go to the doctor, and doctors can't test directly for this. It has to get typed and booted up to the state lab. The individual states make the rules as to which cases they will test, so the numbers by state are not really meaningful.
CIDRAP has already warned that the reported swine flu death rate will rise because of state testing protocols, giving as an example:
Minnesota is among states that have announced a cutback in influenza testing. In a May 4 press release, the Minnesota Department of Health (MDH) said it was asking healthcare providers to submit lab specimens only when a patient has been hospitalized for flu-like like symptoms. It will also continue to accept specimens from the state's 29 sentinel influenza surveillance sites and for ill healthcare workers.
Worldwide (WHO update site), the confirmed count is up to 4,694 cases in 30 countries.
Mexico has 1,626 cases and 48 deaths. The US has 3 deaths. Canada has 284 cases and 1 death.
Before looking at the absolute numbers and leaping to conclusions as to which countries have the highest real infection rates, consider the case count in CA (282) and the case count in Canada (284). Canada's population is more than 3 million less than CA's, so if one were to assume that there is similar coverage in testing, one would infer that Canada has a similar to greater infection level in the population.
Mexico's confirmed 48 deaths likely indicate a higher level of infection in their population.
Costa Rica has confirmed 8 cases and 1 death. You do the math. With a mild flu, it's all in how you do the testing. There were clearly a number of deaths in Mexico from another flu romping through the community at the same time as this novel H1N1 virus, and since Mexico's official case count is much reduced, it's anyone's guess as to how much of their flu epidemic was really due to the H1N1 versus other strains.
Outside of the Americas, the highest confirmed case counts are in Spain (95) and in the UK (47). Spain reports that at least 5 cases were not imports (travelers coming from infected regions) but contacts of infected people. It's easier to screen air travelers than to screen ships, so in a few months this virus will have traveled by ship everywhere, and will have expanded through borders.
The gold standard for estimating flu epidemics is still mortality and morbidity. In a severe flu epidemic, death counts from pneumonia/influenza will rise out of their normal ranges, and mortality will rise among the young. The US issues the weekly mortality report which can be accessed on Wonder, and using the traditional metrics, it becomes clear that the impressive swine flu case counts for Wisconsin and Illinois do not seem to have translated into higher deaths.
This is the report to watch for abnormalities, although the week-by-week variance does not mean as much. Generally when flu epidemics are starting, you see a three-week rise in P/I deaths, P/I deaths rise to over 10% of the total, and total deaths rise. Also indicative are rises in the death rates for the under 1 and under 24 groups.
By those standards, the US has not been experiencing anything suspicious. However, week 17 showed two early possibles, which are the New England region and West South Central (TX, LA, OK). It's too early to say if either of those are real, especially since the WS Central blip is concentrated in San Antonio, and the counts for the prior week in San Antonio are suspiciously low. Another thing is that it is consonant with this year's pattern in San Antonio, so it's a little iffy to attribute any abnormality to this particular strain of the virus, or alternatively, if one were to do so, the most probable conclusion would be that this virus has been there long enough that one could be reasonably certain it won't suddenly do something different.
As far as assessing the currently-expected economic consequences, what we would expect with the virus in its current state is that it is unlikely to be a problem for developed countries with high-level medical systems. They will spend more money on adjunct immunization programs, but their overall medical systems should be sufficient to compensate.
Looking at Mexico, which is mid-range, and has poorer populations with high levels of endemic bacterial infections, one would also guess that this virus might cause problems for less-developed nations. Since it is novel, there is less immunity, and the greater incidence of serious consequences for flu coincident with other health problems can cause much more serious consequences.
In Mexico, the flu outbreak (which was not just H1N1) and the attempts to control it have abruptly produced much more negative near-term economic projections. Some of them are detailed in this Bloomberg article:
“The economy is going to need a substantial stimulus to beat this slump,” said Mendez, 37. “If we thought the bank was planning on cutting rates before the outbreak, now we think it’s planning on cutting even more.”I don't think anyone would deny that there has been a significant effect. A reasonable estimate of the effect on 09 GDP would probably be in the -0.5% to -1.0% range. The change in analyst estimates has to be seen in the larger context. During this period, many countries have cut their 09 GDP estimates.
Finance Minister Agustin Carstens last week estimated the economy will shrink 4.1 percent this year, compared with a previous projection of 2.8 percent.
Credit Suisse Group AG and HSBC Holdings Plc revised their forecasts for Mexico’s economic contraction last week, citing the effects of swine flu. Latin America’s second-biggest economy will shrink 6 percent in 2009, according to Credit Suisse’s Alonso Cervera in New York. HSBC’s Jonathan Heath in Mexico City forecasts a contraction of 5.9 percent. Cervera and Heath had previously forecast a decline of 3.5 percent and 3.3 percent, respectively.
I think swine flu may be more of a factor than most expect. The offset to it is that the maximum effect will mostly be seen in countries that are heavily dependent on natural resource production, so with any luck, if most of the impact is delayed until next year, the overall impact might be softened by an earlier pickup in those countries.
Young children don't spread germs because they want to, they don't know how NOT to.
Germy Wormy Germ Smart for Kids educates and entertains kids while teaching them how to NOT spread germs.
Please pass along to anyone who has young children and is concerned about the spread of the Swine Flu
That map only shows cases confirmed by PCR testing, even though you are correct that almost all of the unidentifiable Type As are being confirmed as the novel H1N1.
Take care, Elli
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