Readers of Real Answers with Dr. Arthur Lavin will remember that nearly every posting on the influenza virus reminds us that this is a virus that mysteriously appears every year around the same time, and just as strangely, disappears every year in an equally predictable manner.
The Later Phases of the Middle of the 2019-2020 Influenza Virus Epidemic
This influenza virus epidemic, the 2019-2020 epidemic is shaping up to have two peaks of activity. The first peak spiked around the week or so before New Years. We are currently in the second spike, which began to spike in mid-January, and may be slowly waning just now. Until we have a few more weeks’ data, we can’t be sure if the current drop-off will continue.
A distinctive feature of this season’s epidemic is the prominent role played by influenza virus Type B. All the seasonal (Dec-April) influenza virus epidemics are caused by influenza virus types A & B. Typically type A dominates. Last year it caused about 75% of the infections. Not this year, where B is the dominant type. Influenza virus Type A is the type that infects many barnyard animals, hence swine flu, equine flu, and bovine flu. Influenza Type B, by contrast, infects only humans, not animals.
The main problem with influenza virus Type B is that it tends to infect younger people. That is good news for the elderly, and this year appears, so far, to be a safer year than usual. But it is bad news for children, and they are indeed sicker with the influenza virus than in typical years. But a B-dominant influenza virus epidemic year is not unheard of, we had such a cycle last in 1992-1993. Compounding the trouble with influenza virus Type B illness this cycle, is the fact that this year’s flu vaccine is not an exact match for the type B component.
As you may recall, every spring, as the season’s influenza epidemic fades, samples of influenza virus infection in various barnyards are taken across the world, to predict the exact nature of next winter’s epidemic of influenza A,and a guess is made on the strain of influenza B that will appear. Only once the epidemic is on, worldwide, can we know how close the guess contained in that season’s flu vaccine matches the actual epidemic. It is never 100%, but some years it is closer, of course, than others. This year the match in the flu shot for the influenza B strains is more off mark than usual.
Putting that all together, more kids are sicker this year. Sadly, the number of deaths from influenza virus infection in children less than 18 years of age is up too. Sadly, this tragedy struck a young person in our community this year.
The good news is that even so, the chance of actually dying from an influenza virus infection remains very, very, very rare. So far this winter, about 30 million Americans have been infected with the influenza virus. That means about 10 million children 18 and under have had an influenza virus infection already. To date, about 92 children infected with the influenza virus have died this winter. That means the chance of dying from this virus in childhood is about 100 in 10 million, or about 1 in 100,000. That means if a person 18 years old or younger gets infected with the influenza virus this winter, their chances of surviving it are at 99.999% which are outstanding chances!
The huge, almost complete, chance of surviving an influenza virus infection is not very different than in past years. Even at its highest, the number of children who die from these infections across the whole United States has always been less than 200. Horribly tragic, but mercifully actually very, very rare.
The same trends remain true this year as in past winter influenza virus epidemics:
- This season may turn out to be in the middle range for severity, not the worst, not the mildest.
- The epidemics typically go away sometime in April, this one should too.
- Be very wary of scary news reports, when we say the vast, vast majority (99.999%) of children infected with the influenza virus do fine, we really mean it.
- The 2019-2020 remains in force. This winter’s epidemic remains in full swing, many people have the infection, severity appears moderate, a fairly typical winter of high fevers and coughs.
- This epidemic has the unusual feature of influenza virus Type B dominating, a pattern that does happen and happened last in the winter of 1992-1993. Type B epidemics tend to affect children more than Type A.
- Influenza virus infections tend, overwhelmingly, to be not so dangerous to most healthy children.
Of course, we all hope this year’s epidemic is ends soon, and whatever the virus does, we are here to help.
To your health,
Dr. Arthur Lavin