Paul Glezen, M. D., is Professor of Molecular Virology and Microbiology, Pediatrics and Epidemiologist in the Influenza Research Center at Baylor.
Recently I talked with him about the second threat of H3N2 coming while H1N1 cases are doubling each week; why the novel H1N1 virus is hitting the young and
pregnant populations so hard and yet this time, older people seem to have some
immunity. Dr. Glezen begins with the link between the 1918 Spanish flu pandemic
that killed 100 million people and this new H1N1 flu virus.
The 1918 pandemic virus was an H1N1 virus. But the hemagglutinin of the current H1N1 is much different from the 1918 H1N1. Certainly H1N1 from the earlier days (of 1918) is related to this new virus. But this H1N1 does not have the virulence
factors that 1918 did.
All Influenza A Viruses Originated in Birds 2009
Novel H1N1 is an Influenza A Virus
COULD YOU EXPLAIN THAT IF THIS IS A NOVEL VIRUS THAT HAS NORTH AMERICAN SWINE, HAS BIRDS, AVIAN, AND HUMANS IN THE GENETIC
MIX OF THE VIRUS – HOW COULD ANYONE FROM ANY TIME PERIOD HAVE ANTIBODIES TO SOMETHING THAT IS THIS STRANGE?
You have to realize that all Influenza A viruses started originally from birds. But then, they occasionally infect mammals of different species and eventually a virus emerges that will spread readily in humans.
Now, the pig is generally considered the mixing vessel because pigs have receptors for both avian viruses and human viruses.
Influenza viruses have a segmented genome. That is, their genetic material is
divided into eight different segments. It’s very easy then for the viruses to
re-assort and can re-assort in all kinds of combinations. Some of the gene
segments can come from pigs, some from birds and some from humans. That’s what’s happened in this new H1N1 virus. But let me stress that it is now a human virus because it is spreading very readily in human populations.
Another 2009-2010 Flu Threat: H3N2 “The H3N2 is a threat to the elderly population.” Then this winter, we might see seasonal flu – particularly H3N2 produce an outbreak this winter. We’re concerned about that because doctors discovered a
new variant of the virus in the Southern Hemisphere in our summer, their winter,
and that might get up here this winter at the usual time for seasonal flu
peaking in the middle of February 2010.
And H3N2 has been the major cause of mortality since it appeared in 1968. That virus has produced epidemics essentially every other year since it first appeared in 1968.
SO THE POSSIBILITY IS THAT WE MIGHT HAVE EVEN A BIGGER SPIKE IN MORTALITY IN THE H3N2 BECAUSE OF A NEW VARIANT IN ITS GENOME SEQUENCING THAT FIRST APPEARED IN THE SOUTHERN HEMISPHERE AND COULD BE UP HERE THIS WINTER.
Yes, that’s possible because as we have said, the older population, which usually make up the majority of people in the excess mortality category seem to be protected against the new H1N1, but for some reason, they have not acquired protection against the H3N2 variants that have appeared since 1968. So, most of the mortality – and this is largely in elderly people – that has occurred since 1968 has occurred in years when we have had H3N2 epidemics. GOING INTO THE WINTER OF 2009-2010, WE HAVE TWO INGREDIENTS: THE NEW H1N1 THAT IS FOCUSING ON CHILDREN AND PEOPLE IN THEIR 20S AND 30S. THEN WE HAVE THE H3N2 IN A NEW VARIANT THAT COULD BE HARDER
ON OLDER PEOPLE.
That’s correct. So, I think there is a good possibility that we’ll have an H3N2 outbreak in mid-winter of 2010. The H3N2 is a threat to the elderly population.
IS ONE OF THE IRONIES NOW THAT YOU AND OTHER VIROLOGISTS ARE ACTUALLY WORRIED MORE ABOUT H3N2’S IMPACT THIS YEAR THAN H1N1?
No, I wouldn’t say that. The impact is very different depending upon the
age of the person. I think this H1N1 is going to have a very heavy impact on
school age children and college students and there will be some tragic deaths
that occur in very young, healthy people. And that’s why it is important for
everyone now to get the seasonal vaccine as quickly as they can get it so they
will be prepared for this winter.
Safety of H1N1 New Vaccine
WHAT IS YOUR PERCEPTION ABOUT THE CONTROVERSY OVER THE SAFETY OF THE NEW H1N1 VACCINE?
The new vaccine is treated a strain change by the FDA. In other words, they have examined the virus and looked at its growth characteristics and preliminary data from all the vaccine manufacturers and they concluded this is like a strain change that we have every year with seasonal flu. The new H1N1 vaccine is produced in a manner that is no different than seasonal flu vaccines, which we have been using by millions of doses for the past fifty years. So, we have no concern about anything being special about this vaccine.
But, from all the data we have seen, we agree we can treat this
like a seasonal flu vaccine that has a change, but it’s manufactured in the same
way as a seasonal vaccine.
WHAT DO YOU SAY TO PEOPLE WHO ARE AFRAID OF
GETTING ANY VACCINATION OF EITHER OF THE FLU VACCINES (Novel H1N1 or 2009 seasonal flu vaccine)?
I think they need to look at the statistics on the number of people who have been ill and the number of people who have died with the new H1N1 virus. Then they have to weigh the risks and benefits. If those afraid think the risk of the vaccine is greater than risk from infection by the virus, then they can make their choice. But, personally, I think people are much better off if they take the vaccine and get protection against infection with this new virus.
Since August 30th, the U. S. Public Health Service has attributed over 10,000 hospitalizations to the new H1N1 virus and almost a thousand deaths. That’s only for September 2009. And the numbers have doubled each week since September 1, and we have seen skyrocketing change in the number of people who are presenting with influenza-like illness to clinics and emergency rooms. So, I think we can expect those numbers to increase.
It does not appear we have reached the peak of activity for this H1N1 wave yet. So, we’re still going to see a lot of illness before this fall is out.
No Mercury in H1N1 Vaccine for Pregnant Women and Children
The H1N1 vaccine is produced the same way as the seasonal vaccine. The
vaccine that will be given to pregnant women and children will have no mercury
in it. The vaccine in multi-dose vials for older people will have the usual
amount of thimerosal in it.
[ Editor’s Note: National Network for Immunization Information (NNii) - “What is thimerosal, and why is it in some vaccines? Thimerosal is a compound that is 49.6% mercury by weight. Although it is not used in all vaccines (for example, it is not used in measles-mumps-rubella or chickenpox vaccines), it has been part of the
manufacture of many vaccines since the 1930s. Thimerosal has been used: to kill
the bacteria that make the vaccine itself (e.g., whole cell pertussis vaccine)
to kill bacteria that might enter the vaccine during the production process
(e.g., influenza vaccine) as a preservative to prevent bacterial and fungal
contamination of vaccines during their clinical use. In this case, thimerosal is
added at the end of the production process either to the liquid vaccine itself
or — in the case of dry powder vaccines — to the liquid used to dilute the
Now, I want to say there is no evidence that thimerosal has any toxicity. Studies have shown that it is rapidly metabolized and excreted in the bile and does not accumulate and create toxic effects. It’s an ethyl mercury, which is very different than the mercury that causes poisoning, which is methylmercury that is not metabolized rapidly and tends to accumulate and produce toxicity. Methylmercury is found in seafood – particularly tuna and fish like that – and can accumulate and produce toxicity.
So, I don’t think anyone has to worry about the thimerosal in the influenza vaccine in the dose it is given. It’s not going to cause any harm.
WHO WILL BE ABLE TO GET THE H1N1 VACCINE IN THE UNITED STATES?
The goal is to immunize everyone in the country. But if it is the younger people who are having all the infections and are dying from it, it’s better if the new vaccine is targeted toward the younger population and pregnant women. Pregnant women have an excess mortality with this H1N1 that women of the same age who are notpregnant do not have. So, it’s important that we get an activated vaccine for pregnant women and a live or activated vaccine for school kids particularly because if we can get the school kids immunized rapidly, that will slow down the spread of the virus and we will be able to immunize the rest of the American population, hopefully before they have been infected.
How Does H1N1 Kill So Many Pregnant Women? WHY ARE
PREGNANT WOMEN SO VULNERABLE TO THE NEW VIRUS?
They are susceptible to it, that’s one thing. And pregnant women are vulnerable, not because they have a problem with their immunity. They respond to the vaccine very well. But, as the pregnancy progresses, the diaphragm is pushed up so their pulmonary reserve is compromised . And also their cardio-pulmonary reserve is less. Therefore, if they get pneumonia with influenza, they are more likely to die.
Another thing to remember is that if a pregnant woman takes the vaccine, she makes antibodies that are also passed to her new baby. It’s no use to vaccinate babies
before 6 months of age, so the only protection the babies can get against influenza infection are the antibodies they get from their mother. So, if the mother is vaccinated during pregnancy, she will not only protect herself, but she will provide protection for her baby that should last for the first six months of the baby’s life after birth. That is a very vulnerable period for the baby, too.
How Did H1N1 Vaccinations Get Turned Into A Political Football?
There are anti-vaccine groups that seem intent on doing this and it doesn’t matter whether it’s flu vaccine or some other vaccine. Whatever is popular is what they attack. All the studies show that vaccines are very safe and the amount of disease they prevent is amazing!
In this era of high cost of medical care, we should be doing everything we can to prevent illness and reduce costs of health care. Otherwise, we are going to drown in the cost of health care. So, to go against agents that are affective vaccines is againstthe national interest and our economy.
Could the Novel H1N1 Flu VirusMutate
to More Virulence?
THE H1N1 VIRUS COULD JUST KEEP PERKING ALONG UNTIL WHAT?
I think it will produce a pretty sharp outbreak this fall of 2009. Then it might die out a little bit and then it might either re-occur in the winter or come back next year.
WILL IT CHANGE THE HEMAGGLUTININ AGAIN SO THAT IT’S
MORE VIRULENT? OR LESS?
Well, it usually mutates in response to the immunity of the population. Partially, it will depend upon how quickly we distribute vaccine against the current H1N1 virus. Then we might see a change in the virus. But whether or not it will change the virulence, that’s really speculation.
BY THE MIDDLE OF NEXT YEAR, WHAT MIGHT BE THE PROJECTED DEATHS
FROM THE COMBINATION OF THESE TWO VIRUSES THIS YEAR? WHAT IS NORMAL AND WHAT MIGHT HAPPEN?
Normal seasonal flu is 50,000 excess deaths. That’s the average. The direct medical costs plus indirect costs due to disruption of social factors is $87 billion/ year just for seasonal flu. The cost is very high for flu every year.
HOW MANY MORE THAN 50,000 WOULD YOU EXPECT IN
I would expect the total to be 70,000 to 80,000 excess deaths.
NOT QUITE DOUBLING, BUT GETTING UP THERE.
Yes, getting up there, but the age specific mortality will be different because there will be much higher mortality in younger people than we usually see.”
Virus Symptoms Differ Patient to Patient
Another aspect of this novel H1N1 are the differences in symptoms from patient to patient. Recent child deaths in
Indiana and New Mexico shocked the parents because each healthy girl had few
symptoms other than a sore throat and nausea until each suddenly declined, went
to emergency rooms and died without any evidence of other medical complications
other than lab-confirmed H1N1 virus.The more typical symptoms summarized in the
recent CDC research include:
- 39% had diarrhea or vomiting compared to
only 5% with normal seasonal flu- About 40% of H1N1 patients ended up with
pneumonia because the virus especially attacks lung tissue.- All had been put on
breathing machines, but 7% died. Weigh that higher mortality rate against the
fact that about 75% of all these patients in the CDC study had been given
antiviral medicines such as Tamiflu. This means even with the antivirals, mortalitywas higher than normal.
As Dr. Glezen pointed out, with the virulent strain of H3N2 now making its way north on top of the H1N1, deaths from influenza in the United States by February 2010, could nearly double. That’s why it is important for older people to get the seasonal flu vaccine as soon as possible – and why those on the list to receive the H1N1 vaccine now being distributed should get that vaccine as soon as possible.
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