Influenza type A/H1N1 (swine flu) updates

[Ninong]

Here are the latest figures from the CDC (2,254 cases, 2 deaths):



So far we are very lucky that the death toll is as low as it is. Regular season flu usually kills about 1/10 of 1% of Americans who come down with it (36,000 out of more than 3 million cases -- the 3 million cases represents about 1% of the U.S. population).

This novel strain of Type A (H1N1) seems to be attacking teenagers and young adults disproportionately compared to regular seasonal flu. Fortunately for us, it seems no more deadly than regular seasonal flu. Two deaths out of 2,254 cases represents slightly less than 1/10 of 1%.

Mexico has reported 1364 laboratory confirmed human cases of infection, including 45 deaths. That's a mortality rate of 3.3%, which is horrendous!

It could be that early treatment with Tamiflu or Relenza is keeping the mortality rate in the United States down. Those anti-virals do not "cure" the flu, or even prevent it; what they do is lower the viral load, reducing the severity of the symptoms and shortening the period the patient will be ill.

The CDC cautions us that they expect more cases and more deaths in the coming days and weeks.

One of the cable news channels reported a couple of days ago that the WHO is predicting that 2 billion people worldwide will come down with this strain of H1N1 before it runs its course. That figure represents 30% of the world's population. They didn't say anything about a mortality rate prediction or whether that figure of 2 billion was based on not having a vaccine available. It's possible that it's based on having a vaccine available, which is likely, but not having enough vaccine to treat much of the world's 6.7 billion people.

We will just have to hope that the severity of this virus doesn't get any worse than it is right now. Should it get as high as 3.3%, which is what it is right now in Mexico, then we would have 66 million deaths worldwide and 3 million deaths in the U.S. That's based on 30% of the U.S. population (91.8 million) contracting the disease and 3.3% (3 million) dying. If 30% of the U.S. population should come down with this virus, but only 1/10 of 1% die, then the number of deaths would be 91,800. If we can get enough vaccine in time to treat 25% of the population, we could reduce the number of cases and the number of deaths, but that's a big if. Remember that most flu vaccine is manufactured in Europe, so let's be realistic about which countries will get the most doses.

Should the disease prove no more dangerous than regular seasonal flu, then we could expect a mortality rate of 1/10 of 1% of the cases in the U.S. The big unknown right now is the expected morbidity rate (the number of people who come down with it). In a normal flu season, about 3 million Americans get sick. That's only 1% of the population. And we end up with 36,000 deaths. Since this is a new strain, I think it's reasonable to expect that the morbidity rate will be higher than it is with regular seasonal flu. How much higher is unknown.

P.S. -- Excellent NYT article about Dr. Chan and the WHO.

[Ninong]

Here are the latest figures from the CDC (2,532 cases, 3 deaths):



Two of the deaths are in Texas and the other one is in Washington state. Current mortality rate is slightly more than 1/10 of 1%. Current mortality rate in Mexico is 2.8%. It is very likely that Mexico's mortality rate is lower than that because I doubt that Mexico is testing all of their cases.

[Ninong]

Here are the latest figures from the CDC (3,352 cases, 3 deaths):



Two states, Illinois and Wisconsin, represent nearly a third of the total. They're now showing Louisiana with a total of 33 cases but we have a lot more than that. It just takes time to get the specimens tested. I'm surprised that Arkansas and Mississippi have no confirmed cases.

According to the WHO, Mexico has reported 2,059 laboratory confirmed human cases of infection, including 56 deaths. That's not nearly as bad as the 181 deaths originally reported by Mexico's department of health more than a wee ago but 56 deaths out of 2,059 cases is still a horrendous mortality rate of 2.7%. The U.S. mortality rate is now slightly less than one-tenth of one percent. If our mortality rate was the same as Mexico's, we would have 91 deaths right now instead of just three.

[Ninong]

Here are the latest figures from the CDC (4,298 cases, 3 deaths):

[Ninong]

Here are the latest figures from the CDC (4,714 cases, 4 deaths):



The latest death was in Arizona. That makes two in Texas, one in Washington and one in Arizona. Mortality rate in the U.S. is currently slightly less than one-tenth of one percent (0.085%). Mexico has reported 2,446 laboratory confirmed human cases of infection, including 60 deaths. That makes the mortality rate in Mexico 2.5% (2.515%).

We really need to know why the mortality rate in Mexico is nearly 30 times as high as in the U.S. The best answer would be that there are another four thousand unreported cases in Mexico and that their true mortality rate is less than one percent. That would be the best answer. The worst answer would be that the virus originated in Mexico and has now grown stronger there.

Canada has 449 cases, including one death. That's a mortality rate of slightly more than two-tenths of one percent (0.223%). Costa Rica has eight reported cases, including one death. That's too small a sample to worry about the mortality rate. Those are the only other countries with reported deaths. As of this morning, the WHO reports more than 7,500 confirmed cases in a total of 34 countries.

P.S. -- Texas reported another death today (Friday), bringing the U.S. total to five, but it's not in the CDC's figures yet.

From the CDC:

A New Influenza Virus

Novel influenza A (H1N1) is a new flu virus of swine origin that was first detected in April, 2009. The virus is infecting people and is spreading from person-to-person, sparking a growing outbreak of illness in the United States. An increasing number of cases are being reported internationally as well.

It’s thought that novel influenza A (H1N1) flu spreads in the same way that regular seasonal influenza viruses spread; mainly through the coughs and sneezes of people who are sick with the virus.

It’s uncertain at this time how severe this novel H1N1 outbreak will be in terms of illness and death compared with other influenza viruses. Because this is a new virus, most people will not have immunity to it, and illness may be more severe and widespread as a result. In addition, currently there is no vaccine to protect against this novel H1N1 virus. CDC anticipates that there will be more cases, more hospitalizations and more deaths associated with this new virus in the coming days and weeks.

Novel influenza A (H1N1) activity is now being detected through CDC’s routine influenza surveillance systems and reported weekly in FluView. CDC tracks U.S. influenza activity through multiple systems across five categories. The fact that novel H1N1 activity can now be monitored through seasonal surveillance systems is an indication that there are higher levels of influenza-like illness in the United States than is normal for this time of year. About half of all influenza viruses being detected are novel H1N1 viruses.

CDC Response

CDC continues to take aggressive action to respond to the outbreak. CDC’s response goals are to reduce the spread and severity of illness, and to provide information to help health care providers, public health officials and the public address the challenges posed by this new public health threat.

CDC is issuing updated interim guidance daily in response to the rapidly evolving situation.

Clinician Guidance

CDC has issued interim guidance for clinicians on identifying and caring for patients with novel H1N1, in addition to providing interim guidance on the use of antiviral drugs. Influenza antiviral drugs are prescription medicines (pills, liquid or an inhaler) with activity against influenza viruses, including novel influenza H1N1 viruses. The priority use for influenza antiviral drugs during this outbreak is to treat severe influenza illness, including people who are hospitalized or sick people who are considered at high risk of serious influenza-related complications.

Public Guidance

In addition, CDC has provided guidance for the public on what to do if they become sick with flu-like symptoms, including infection with novel H1N1. CDC also has issued instructions on taking care of a sick person at home. Novel H1N1 infection has been reported to cause a wide range of symptoms, including fever, cough, sore throat, body aches, headache, chills and fatigue. In addition, a significant number of people also have reported nausea, vomiting or diarrhea. Everyone should take everyday preventive actions to stop the spread of germs, including frequent hand washing and people who are sick should stay home and avoid contact with others in order to limit further spread of the disease.

Testing

CDC has developed a PCR diagnostic test kit to detect this novel H1N1 virus and has now distributed test kits to all states in the U.S. and the District of Columbia and Puerto Rico. The test kits are being shipped internationally as well. This will allow states and other countries to test for this new virus. This increase in testing will likely result in an increase in the number of confirmed cases of illness reported. This, combined with ongoing monitoring through Flu View should provide a fuller picture of the burden of disease in the United States over time.

See Also:
FluView Surveillance Report (PDF 277KB)
For the week ending May 2, 2009

[Ninong]

As of 11:00 AM, May 19, there have been 5,469 confirmed cases, including 6 deaths. Three deaths in Texas, two in Arizona and one in Washington.

Using those official figures, the U.S. mortality rate is slightly above one-tenth of one percent (0.11%).

Mexico's total is now 3,648 confirmed cases, including 72 deaths -- a mortality rate of 2.01%.

[Ninong]

As of 11:00 AM, May 20, there have been 5,710 confirmed cases, including 8 deaths (2 in Arizona, 1 in Missouri, 1 in New York, 3 in Texas and 1 in Washington). That's a mortality rate of 0.14%.

[Ninong]

W.H.O. About to Declare Pandemic (Level 6)

The purpose of this thread is to track the progress of the new strain of Type A (H1N1) flu virus, so I guess it's about time for an update. We have been very lucky so far that this new virus is nothing compared to H5N1 (avian flu) that we had a thread on back in 2005. The H5N1 avian flu virus, which isn’t easily transmitted among people, has killed 61 percent of the 432 people known to have been infected since 2003. This new strain of swine flu (H1N1) is more easily transmitted but it is much less severe than H5N1, having killed only 117 people so far worldwide.

The W.H.O. will declare the first pandemic in the past 41 years as soon as they can come up with a severity index to announce simultaneously. Level 6 simply means that the virus is pandemic (widespread) around the globe. It says nothing about the virulence of the virus. This particular strain is very mild, so far at least. H1N1 is now spreading in 66 countries.

The latest U.S. figures on the CDC's website show 11,054 total cases, including 17 deaths. That's as of 11:00 AM, Wednesday, June 3.

[Ninong]

The latest U.S. figures on the CDC's website show 13,217 total cases, including 27 deaths. That's as of 11:00 AM, Friday, June 5, based on data reported to the CDC by 5:00 PM ET, June 4.

[Ninong]

A Pandemic Is Declared

On June 11, 2009, the World Health Organization (WHO) raised the worldwide pandemic alert level to Phase 6 in response to the ongoing global spread of the novel influenza A (H1N1) virus. A Phase 6 designation indicates that a global pandemic is underway.

More than 70 countries are now reporting cases of human infection with novel H1N1 flu. This number has been increasing over the past few weeks, but many of the cases reportedly had links to travel or were localized outbreaks without community spread. The WHO designation of a pandemic alert Phase 6 reflects the fact that there are now ongoing community level outbreaks in multiple parts of world.

WHO’s decision to raise the pandemic alert level to Phase 6 is a reflection of the spread of the virus, not the severity of illness caused by the virus. It’s uncertain at this time how serious or severe this novel H1N1 pandemic will be in terms of how many people infected will develop serious complications or die from novel H1N1 infection. Experience with this virus so far is limited and influenza is unpredictable. However, because novel H1N1 is a new virus, many people may have little or no immunity against it, and illness may be more severe and widespread as a result. In addition, currently there is no vaccine to protect against novel H1N1 virus.

In the United States, most people who have become ill with the newly declared pandemic virus have recovered without requiring medical treatment, however, CDC anticipates that there will be more cases, more hospitalizations and more deaths associated with this pandemic in the coming days and weeks. In addition, this virus could cause significant illness with associated hospitalizations and deaths in the fall and winter during the U.S. influenza season.

Background

Novel influenza A (H1N1) is a new flu virus of swine origin that first caused illness in Mexico and the United States in March and April, 2009. It’s thought that novel influenza A (H1N1) flu spreads in the same way that regular seasonal influenza viruses spread, mainly through the coughs and sneezes of people who are sick with the virus, but it may also be spread by touching infected objects and then touching your nose or mouth. Novel H1N1 infection has been reported to cause a wide range of flu-like symptoms, including fever, cough, sore throat, body aches, headache, chills and fatigue. In addition, many people also have reported nausea, vomiting and/or diarrhea.

[Ninong]

Number of deaths nearly doubled since last report

The latest U.S. figures on the CDC's website show 17,855 total cases, including 45 deaths. That's as of 11:00 AM, Friday, June 12, based on data reported to the CDC by 5:00 PM ET, June 11.

[Ninong]

Update as of July 2, 2009:

Number of U.S. cases: 33,902

Number of U.S. deaths: 170

One teenager in San Francisco has come down with a drug-resistant strain of Type A (H1N1) 2009. It's resistant to Tamiflu. This is only the third such case in the world. The other cases are in Japan and Denmark. That still leaves one other drug that is effective. A vaccine is in the works but it won't be ready until the fall and quantities will be limited.

This is not unexpected. Flu viruses can mutate rapidly and are capable of developing resistance to antivirals.

[Ninong]

Update as of July 10, 2009:

Number of U.S. cases: 37,246

Number of U.S. deaths: 211

It is unusual that flu virus would continue to cause problems in the U.S. this late into the summer. This is not our flu season. The concern is that the virus will be stronger in the fall when our usual flu season begins. Hopefully we will have a specific vaccine by then, although in limited quantities.

The number of laboratory-confirmed cases is picking up in countries in the Southern Hemisphere. Australia is now reporting 5,298 cases, including 10 deaths. Argentina reports 2,485 cases, including 60 deaths. Chile has 7,376 cases with 14 deaths.

Worldwide the WHO is reporting a total of 94,512 laboratory-confirmed cases, including 429 deaths. Nearly 40% of the total number of cases and 49% of the deaths are in the United States but that could very well be because we have better testing and tracking capabilities than most our countries. Mexico, for example, is reporting 10,262 cases, including 119 deaths, but it's quite possible that those numbers do not reflect the true totals in that country.

There have been no new reported cases of Tamiflu-resistant virus other than the three isolated cases previously identified. All three of those patients did not have severe disease and all have recovered. The virus they had was resistant to Tamiflu but sensitive to Relenza. All of the other Type A (H1N1) 2009 viruses tested to date have been resistant to both Tamiflu and Relenza.

[Ninong]

Update as of July 17, 2009:

Number of U.S. cases: 40,617 (Make that 60 million as of March 2010)

Number of U.S. deaths: 263 (Make that 12,000 as of March 2010)

The WHO announced that they will no longer release the number of laboratory-confirmed cases any longer because many countries don't have the facilities to test large numbers of samples.

Besides, the results they were reporting did not reflect the true magnitude of the situation anyway. Some countries are grossly underreporting the number of cases.

In the US, the CDC announced that they will discontinue tracking individual cases shortly, following the example of the WHO.

In Britain, the government estimated that there were 55,000 new cases there just last week alone. That's an estimate, not actual laboratory-confirmed cases, which shows why the numbers reported by the WHO make no sense at all.

The WHO will continue to minotor the pandemic, they just won't be releasing numbers of individual cases.

[Ninong]

It's been a long time since we updated this thread, so here goes.

U.S. Surgeon General Dr. Regina Benjamin said that approximately 60 million Americans have been infected with the H1N1 virus and 256,000 people have been hospitalized. There have been close to 12,000 deaths from the virus which, while notable, is still far less than the 36,000 usually reported from the seasonal flu each year.

Ninety percent of the 12,000 deaths in the United States have occurred in individuals under the age of 65, about five times the death rate seen in this age group with the seasonal flu. Most of those hospitalized had not been vaccinated, Schuchat said.

Officials see new uptick in H1N1 cases.