Is H2H spread of H3N2v occurring in the United States?

[alert]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Iowa has announced a three-person confirmed cluster of human trH3N2 with no apparent swine link:

http://www.flutrackers.com/forum/showthread.php?t=176893

I would think that more cases would have been detected by now if this were ongoing spread of a novel influenza (as in 2009), but it seems clear that more than just some H2H is going on. It seems now that we are in novel territory on this one.

Might cross-resistance from previous seasonal H3N2 viruses be preventing this new virus from producing a pandemic? If the H3N2 viruses that circulated in the 1990s were similar enough to this virus to provide adults immunity, this virus could be circulating at low levels in children with these sporadic detections. (Although why was one of the confirmed cases a 59-year-old veterinarian?) More testing is badly needed. Even efficient H2H might not result in a pandemic if a sufficient number of people have prior immunity.

If this is the case, these trH3N2 cases may be quite mild as well, as no cluster of severe respiratory disease has occurred, even though this virus may have been circulating for quite some time now.

Is this Pandemic Stage 4? That would require sustained H2H. Is this sustained? Only time will tell.

 

[alert]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

The detection of human infections with trH1N1 in Wisconsin and trH1N2 in Minnesota, both with the M gene from 2009 H1N1 raises the possibility that this is not a continuous chain of transmission, but rather an after-effect of the 2009 pandemic.

http://www.flutrackers.com/forum/showthread.php?p=433409&posted=1#post433409

http://www.flutrackers.com/forum/showthread.php?p=432032

Perhaps the presence of a swine-like virus in humans (2009 H1N1) is enabling further reassortment in swine and jumps of other swine viruses to humans?

 

[alert]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Well, we're in new territory once again, with about 200 confirmed/suspected human H3N2v infections in the past couple weeks in Indiana and Ohio. Is it really possible that most of these cases are the result of swine contact? Or is this now sustained H2H?

Are we still using the old pre-2009 pandemic alert scale for H3N2v? If so, this looks a lot like stage 4 now. Or does that scale not apply because H3N2v is not a pandemic candidate due to existing human immunity?

 

[Giuseppe]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

The scenario may rensemble that seen in 1977 when the displaced H1N1 strain re-emerged causing the children-pandemic, well described by the late E. Kilbourne.

This may impact the magnitude of the international response and the WHO alert level could be raised soon, but I am not sure if from 3 to 4 or to 5-6.

H3N2v has unique antigenic properties and may impact differently among populations, according the age (children almost naive and the elderly well known to be much more prone to H3N2 complication than H1N1 seasonal counterpart), the presence of comorbidities and health care infrastructure.

 

[alert]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

What is odd about this is that H3N2v has part of both 2009 H1N1 (the M gene) and part of the other circulating H3N2 viruses (at least, their ancestors from the 1990s). I don't know if all three viruses could co-circulate (H1N1, old H3N2, H3N2v) or whether the H3N2v would repleace one or both of the existing ones.

I also wonder what would happen with regards to reassortment/recombination between seasonal H3N2 and H3N2v if both viruses are circulating.

 

[Giuseppe]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

It is a complicate scenario.

The current H3N2 seasonal strain antibodies seem to be poorly reactive against H3N2v, but if an individual had a recent encounter with flu - for example in southern hemisphere - it is possible that the short-term humoral response may preclude infection with the novel strain.

The immunological original sin may pose further problems: people born after 1968 could have a lower cross-protective antibodies against 1990 circulating variants, so that they can serve as H3N2v reservoir.

Conversely, people born before 1990 and after 1968, may be partially protected, making possible the above mentioned children pandemic re-run.

This for the antigenic properties.

The genetic constellation (with the Matrix gene from H1pdm09) will play also a role in morbidity and mortality, especially in the most susceptible people for complications, pregnant women, old adults and small children.

 

[JimO]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

I find it hard to believe that public health officials are sticking with the theory that H3N2v is still swine to human and not H2H. For all we know, the swine at the fairs might be getting it from people, not the other way around.

I wonder what would be done differently if these were all found to be H2H cases. Also, let's go back, say, five years. If prior to pH1N1 there had been 200 confirmed cases of a novel influenza due directly to swine contact, I suspect that the sense of urgency would have been significantly higher. I remember in April 2009 we were tracking cases by state and there were no clusters as large as we are seeing in Ohio and Indiana. There was a tremendous amount of concern about a bad Pandemic.

Remember this thread?

http://www.flutrackers.com/forum/showthread.php?t=101242

The fact that we were lucky, so to speak, and didn't see millions of fatalities is no reason to be less vigilent. Just because there have not been any hospitalizations or deaths attributed to H3N2 doesn't mean it will be a mild strain of flu. I believe that this warrants more attention than it is being given.

 

[Laidback Al]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

From a public relations point of view, the cluster of cases associated with local fairs allows the CDC and WHO to continue to claim animal to human infection rather than H2H. At least so far.

Will this novel virus break out H2H, and if so, what are the public health implications? So far no deaths attributed to H3N2v. The issues of influenza infection that Guiseppe brings up about children, old people, and pregnant women are always relevant for any influenza virus.

We are not in influenza season in the Northern Hemisphere, but I think that H1N1pdm09 showed us that a novel strain can develop anytime.

I agree with JimO that we were lucky with swine flu (relatively speaking) in 2009. So we need to keep on being vigilant.

There is one question that intrigues me the most. Has our monitoring and testing technology here in the USA outstripped out models of pandemic influenza strains?

The H3N2v was identified in humans last year, but did not go pandemic. Will it go pandemic this year?

We are now able to track minute sequence variations from one sample to the next. But do we understand enough about these changes and how they affect transmission and virulence to determine which strains will go pandemic? And if so, can we be certain enough to raise worldwide pandemic levels and expend scarce resources to develop and manufacture vaccines?

The worry is that if we cry "wolf" once too often, people will ignore the warnings when a future pandemic turns out to virulent.

 

[Giuseppe]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

I agree, the swine influenza outbreaks are a symptom of an illness that may die-off as itself or sparks a widespread health emergency.

In any case, viruses belonging to H3N2 subtype are well known to be much more virulent and capable to cause severe illnesses in people with more than 65 year of age, and in other with underlying conditions.

Usually, when H3N2 (human, seasonal) is the predominant strain, the overall morbidity and mortality are higher than the predominat is a type B or H1 subtype.

With this novel H3N2v the situation may be somewhat different, because of the low or absent immunity in children and the waning immunity in the elderly.

A bimodal distribution of cases, coupled with the usual complications-prone conditions such as the above mentioned, may result in a substantial impact on public health infrastructure, as seen during H1pdm09 pandemic or even worse.

Genetic constellation will play also a role, however we cannot predict it until a larger portion of population will be affected.

1968 H3N2 pandemic was the mildest among those happened during XX century, but in some geographic areas the morbidity and mortality was higher than in others, with a great number of fatalities: for example, in Italy during 1968-1970 seasons, it was estimated a death toll of around 30,000 people.

Taken into account the fact that seasonal influenza vaccines are not able to elicit a cross-protective immunity in children and that in young adult they boosts previous acquired immunity, it remains open the window for an attempt to slow down the progression of the epidemic through an immediate, targeted and as large as possibile, deployment of the available stocks. A specific monovalent H3N2v vaccine, although in advanced state of production, will not be available for the first wave.

It is anticipated that severe cases will occur, an taken into account the demographic distribution of regular H3N2 flu outbreaks, a number of people in old ages could be fatally ill.

 

[Vibrant62]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Remember too that there are three major problems faced by decision makers.

1. Even if this is going H2H there is no guarantee that this strain will, in fact, develop into a pandemic. It could burn out (See the Ranicello article)

2. The world is struggling badly economically. When large funds were directed to pH1N1 there was much international political outcry as it proved to be 'mild' (even though the later data showed this not to be the case in those under 45)

3. Vaccine issues still remain. It would take a minimum of 6 months from todays date, diverting all vaccine production resources, to produce a first vaccine in any meaningful quantities. By this time a first, if not a second wave will be long gone having done its damage. Right now, vaccine capacity is in full occupation making seasonal trivalent strains, in preparation for September onwards - and this years seasonal H3N2 is causing trouble enough in the S. Hemisphere (see reports in Australia)

TPTB announced just yesterday I think that work was beginning to develop a seed strain for H3N2v as a precaution. I do not expect to see any public alarm called unless or until there is evidence that this flu - should it go H2H - will cause any significantly greater problems that the seasonal variant already is.

Simply put, policy makers do not like to call 'problem' until they can deliver a solution.

 

[Giuseppe]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Vaccine seed for H3N2v has been shipped to manufacturer (Novartis, Siena, Italy) in February 2012: http://www.flutrackers.com/forum/showthread.php?t=182731

 

[JimO]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

The worry is that if we cry "wolf" once too often, people will ignore the warnings when a future pandemic turns out to virulent.

I think we are already there. We are less prepared now for a major pandemic than we were in 2008. No new antivirals are available. The problem with matching a vaccine to the strain that will emerge is no different. There have been no contingency plans developed for real school closures or cancellation of large public events developed since 2009. And, people are far more complacent about flu since the 2009 Pandemic appeared to have fizzled.

My concern is that if this does develop into a Pandemic virus, the WHO will be much more resistent to officially declaring a Pandemic. I fear that by the time it is recognized as a virulent Pandemic, it will be widespread and too late to do anything but react to circumstances as they arise.

 

[Giuseppe]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

True.

Peramivir remains an investigational drug, and its clinical use is limited in individual cases for compassionate treatment.

Laninamivir is available only in Japan and combination therapies with adamantanes+ribavirin+oseltamivir never reached clinical trials.

Other adjuvant drugs, as immunomodulants, statins, cox-2 inhibitors were almost forgotten.

Vaccines: the idea of a virus seeds library was good but nobody seems to want to proceed into this way.

For example, to override the long process of trials and approval by national drugs agencies, the idea proposed contemplates the use of the seeds that match well with the newly emerged strain.

In the H3N2v case, the seeds may be one of the seasonal trivalent vaccines available during first half of 1990 decade.

It would be not the best for effective protection but could play a role in make the illness milder and boost protection in people already infected with parent strains.

Current H3 component of TIV may also be useful to reduce transmission in affected area in people older than >10 year of age, with or without use of adjuvants or double dosage.

The aim of health authorities could be also to seek information about clinical course during these limited extension outbreaks, pathogenesis, viral shedding and treatment effectiveness or failure.

To date, no paper are available about the features in humans of the infection by H3N2v.

 

[alert]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

The CDC report now claims that all cases confirmed so far in this cluster have had at least indirect swine contact. If that's true, then this isn't stage 4 or 5, as they are still claiming that no sustained H2H is occurring.

There is at least one precedent for this. In 2003, 89 human infections, including one fatality, were reported from the Netherlands with an avian H7N7 virus. Little or no H2H was observed, and when the virus was eliminated from its animal source, human infections stopped.

 

[jeffrey]

Re: Ohio: Human infections with H3N2v virus - 102 cases in 23 Counties - 1 fatality

Re: Ohio: Human infections with H3N2v virus - 102 cases in 23 Counties - 1 fatality

Now we have a death, so when is CDC going to do something???

 

[alert]

Re: Ohio: Human infections with H3N2v virus - 102 cases in 23 Counties - 1 fatality

Re: Ohio: Human infections with H3N2v virus - 102 cases in 23 Counties - 1 fatality

Now we have a death, so when is CDC going to do something???

I moved that post here, as this thread seems to be the place to discuss what the CDC (or anyone else) should be doing about H3N2v.

I'm not sure what else they can do right now. There is a vaccine in development. Pigs are being removed from agricultural fairs. Perhaps I would like to see a bit more contact tracing or quarantine of suspected/confirmed cases, but there really isn't much they can do now. Only time will tell what the future of H3N2v is.

The number of new confirmed cases each week does appear to be decreasing.

 

[jeffrey]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

I apologize for being in wrong spot.

I know CDC stated there may be deaths, but if you know that, then do something about it! I feel CDC is really sweeping this under the rug. One death is too many when the swine barns should have been shut. Sorry, I guess we did not learn anything from 2009!!!!!

Now is the time to act before anymore deaths occur!

 

[JimO]

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

Re: Is H2H spread of a novel swine H3N2 occurring in the United States?

I would like to see serious school closure and event cancellation plans put into place in the event that we have a virulent strain emerge. Such plans would have multiple stakeholders who should be consulted during development. Logistics should be worked out on paper, at least, so people know what to expect.

It was clear in 2009-10 that people weren't serious about aggressively limiting the spread of pH1N1. I realize that these measures won't stop the spread of a virulent flu virus, but it could delay the spread enough to allow for effective vaccine development and, more importantly, lengthen the period during which cases develop so that the healthcare system isn't overwhelmed at any given time.

As it is, I believe that we are less prepared for a major outbreak than we were in January 2009. How many dress rehearsals do we need to go through before an H5N1 strain catches us unprepared?

 

[Laidback Al]

Re: Is H2H spread of H3N2v occurring in the United States?

CDC H3N2v Surveillance

There is growing concern about CDC surveillance for the spread of the H3N2v virus from human-to-human (H2H). The situation reminds me of the old drunk/lamppost joke.

<!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--> Late one night, a drunk is crawling around under a lamppost looking for his lost keys. A policeman comes over and asks him what he is doing. “I lost my keys over in the park and I am looking for them.”

The policeman is puzzled. “Then why are you looking for them all the way over here?”

The drunk replies, “Because the light is so much better here under the lamppost”.

I guess it is easier for the CDC to search under the lampposts at state and country fairs for H3N2v cases that to search more broadly for H2H H3N2v cases.
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