| Well, again we have good news and bad news. The bad news is that we are indeed in the early stages of a worldwide influenza outbreak, and it has killed a number of people. The good news is that here in the USA this outbreak has not yet proven to be severe. But we don't know yet how this will turn out in the end, or even how this first wave will turn out. There are many unknowns when it comes to the flu.
"I do not know". Those are the words I hear from responsible influenza scientists in response to many questions about this current pandemic. That's not what we are hearing from the media because "We don't know" does not sell papers or improve viewer and listener numbers. As a result there has been a lot of misinformation circulating. This update will concentrate on what we DO know, what we think to be true, what we expect to happen (and why), what might happen (and why), and what I recommend people do, and why.
We know the following:
Confirmed cases in the USA have continued to increase over the past week. {Comment- this was expected. Many more people will get sick before there is enough immunity in the population to limit the number of new cases.}
CDC has stated that they will not attempt to confirm new cases in an area where the presence of the Mexican Flu has already been confirmed, but will focus testing on suspect samples from areas that have no confirmation yet. {Comment- this means that the actual case numbers will remain significantly greater than those 'confirmed'. Or in other words, don't put much stock in the 'confirmed case count' as any measure of the spread or prevalence of this disease.}
There have been two confirmed deaths from this virus in the US, and over 30 people have been hospitalized. The median age of those taken ill is under 20. This virus may be different from the 1918 virus in HOW it kills people, but it can be lethal when given the opportunity.
The apparent severity of the disease as it presents in Mexico is greater than in the USA. The reasons for this are not known; more about this later.
'Mild' for an epidemiologist is not what a layperson would call mild. When the media says 'mild', what they mean is you probably won't die. Mexican flu symptoms include:
Fever of up to 104 degrees F
Severe muscle pain
Severe bone and joint pain
Severe nausea
Vomiting
Diarrhea
Debilitating weakness both during and after.
{comment- Hydration fluids, anti-viral drugs, and OTC meds for these symptoms are a good thing to have on hand. Another way to put it is that you can be so sick that you cannot text. Apparently this resonates with teenagers}
Immuno-compromised people, those with chronic respiratory ailments, and pregnant persons are especially at risk from influenza. If you are in one of these risk groups, be especially careful to avoid infection.
I think the following is true:
This Mexican Flu virus appears highly infectious, based on the rapid increase in reported and suspect cases. Suspect case counts double in less than 2 days.
Based on the scanty epidemiological data and case descriptions, it appears that hundreds of people have died from it in Mexico, but the data are fragmented, and the actual total will never be known.
The apparent difference in severity between Mexico and the USA could be explained by one or more of the following factors:
This flu strain does not present as typical flu; there is far more GI involvement, for one thing, and much greater myalgia, for another.
Misdiagnosis during the early stages of this outbreak in Mexico seems highly likely, whereas the US had more warning and knew better what to look for.
It seems likely that the total number of Mexican cases has been significantly under-reported; the vast majority of milder cases were probably never recorded as flu cases. A seroprevalence study would help, but those results would not be available for months.
Mexican culture and economic conditions discourage those taken ill from seeking professional treatment until much later in the course of the disease; Most Mexicans won't go to the doctor until they are VERY ill.
Tamiflu was not generally prescribed until late April when the nature of the outbreak was determined; Mexican cases treated early with Tamiflu show roughly the same prognosis as US cases.
So far, the USA has seen relatively few cases, and fewer still have progressed to conclusion. {We may yet see significant numbers of hospitalizations and more deaths here in the US.}
Mexico City has one of the highest population densities on Earth, encouraging a higher initial infectious bolus, and more possibility of infection;
Mexico City's poor water quality discourages adequate hydration; dehydration is a significant amplifier of the severity of any influenza outbreak;
There may be other factors, but the takeaway message is that it is TOO EARLY TO SAY that we can safely ignore this pandemic outbreak.
The virus appears to continue to be Tamiflu sensitive; early use of Tamiflu is thought to be one reason why the death rate so far in the USA has been lower than in Mexico. {comment- There is no way to know when this will change, but most experts are very concerned about this eventuality, and I agree with their concern.}
There is debate about this in the scientific community, but this virus appears to have a longer than normal incubation period, and a longer than normal infection period compared to seasonal flu. There is speculation that this may be one reason why this virus is so infectious.
Non-Pharmaceutical Interventions appear to be effective. Mexico significantly slowed their outbreak by closing down all public functions for a week. School closings appear to slow the chain of infection in our children.
What we can expect to happen:
I expect to see case counts increase for the next several weeks, until a significant fraction of the population has been exposed and infected. It would not surprise me to see 100 times as many cases in three weeks. Although you may not yet have experienced it, or know anyone that has, if this reproduction rate continues, you soon will. This means that there will be 100 times as many opportunities for the virus to acquire nastier characteristics.
When that 'knee' or leveling off will be seen is dependent on too many variables, including weather, for anyone to be able to confidently predict at this time, but at some point, the number of new cases will stop increasing. In past pandemics, this started to occur once about 15-25% of the population had become ill; ultimately, I expect somewhere around 1/3 of the people in the US to have had some form of this disease. This may be a low estimate; nobody knows for sure.
With CDC revising the recommendation for school closure, I expect to see many fewer school closures, and an increase in the rate of school age infections.
If past history is any basis (and it may or may not be, for reasons discussed later) then we may see a respite in June or early July due to hot weather which may last until the fall, at which time we may see a return, a second wave, which might be more severe than this one.
Eventually, I expect to see this virus acquire the Tamiflu resistance gene, and Tamiflu will no longer work. There is no way to know when this will happen, but the consensus opinion is that it will. This change may or may not include Relenza resistance; it depends which genes it picks up. The selection pressure for Relenza resistance is thought to be lower than that for Tamiflu resistance, but there is no way to know for sure what will happen. The consensus opinion is that Relenza resistance is less likely, but it is not known whether or not Relenza will continue to be effective.
At best, the health care system will be severely stressed if enough people get sick, and at worst, it might not be able to function. Shortages of anti-viral drugs are already reported, and the present vaccine production in the USA will only protect a fraction of the population. Shortages of care, vaccines and drugs can be expected, either this summer or more likely later this fall.
What might happen:
With the changes in travel since the last great pandemic in 1918, the waves that we have seen in past pandemics may not occur. It may be that we won't see any summer downturn in cases, and that there will be continual re-infection of North America from the Southern Hemisphere, and vice versa. This acceleration of viral evolution could result in a continuous chaotic pandemic of increasing severity which might progress for 12-24 months, or longer. No way to know how likely this is, but it is being discussed as a possibility.
It is also possible, for reasons we do not know, that this outbreak will quickly fizzle out soon, and not return until the fall. It is even possible that it may never return. I think this to be highly unlikely, given what we have seen so far, but it cannot be ruled out. I would not, however, bet my family's well-being on it.
It is possible, if enough people get sick, either during this first wave or later on in the year, that there would be interruptions in power and phone service, or to water and sewer service in towns and cities. The Internet could be down. These service interruptions could be brief, or extended. If generation capacity were affected, and not just the upkeep of the power distribution system, these outages could be prolonged.
Health care facilities, especially hospitals, could be swamped if enough people get sick at once. Doctors and nurses have a higher infection rate than the general public, so if this virus becomes widespread, it may be difficult or impossible to find professional treatment.
It is possible that this H1N1 virus could swap genes or portions of genes with other influenza viruses now circulating in human, or other mammals, producing a more virulent strain, possibly much more virulent strain. The Mexican Flu is currently showing a case fatality rate of about the same as the 1918 pandemic, when Tamiflu is not used; simply acquiring the Tamiflu resistance gene would multiply hospitalizations and deaths many fold, and this is not the worst possible outcome. There are possible nightmare scenarios that I see no point in discussing here, but they do exist.
In view of the above, here is what I recommend:
Continue to exercise reasonable prudence, because WE DO NOT KNOW what will happen. An influenza pandemic is a marathon, not a sprint. If this pandemic is like the others we have historical records on, we are only in the early stage of the first of what may be several waves. I suggest that you limit your exposure to limit the opportunity this virus has to change into something worse, and to keep you and your family from having to experience an extremely unpleasant and possibly deadly disease.
Make a pandemic plan. Prudent people prepare properly.
Stock up on essentials:
Food
Water
Medicine
Sanitary supplies
PPE
Avoid getting ill-
Exercise cough discipline;
Practice social distancing;
Practice good hand hygiene
Avoid interaction with obviously ill individuals.
Avoid 'sharing' the flu with others; stay home if you are sick, and encourage sick people to stay home.
Educate yourself and your family on what the flu is, and how to treat it. Check out these websites-
FluWiki
GetPandemicReady
PlanForPandemic
CDC
WHO
BirdFluManual
Make sure that your family knows the plan; having flu medicine stockpiled will be no good if the only person who knows where things are kept is ill.
Continue to monitor this outbreak. Check the CDC pages and the flu blogs regularly.
In particular, I would recommend that you NOT actively seek this infection. There is no way to know what sort of case you will get, nor is there any way to know whether an early infection will confer any immunity against a subsequent strain of this virus.
I solicit comments and questions, and if anyone wants to copy some or all of it, feel free! |
