When it comes to the flu season, the only thing we can be absolutely sure about is this: it will happen every year. We are notoriously bad at predicting virtually everything related to the flu, including the timing and severity of the season, so we rely on small clues to try to anticipate the virus. And so far, this year's suggestions point to a particularly nasty and early flu season. So get your shots now, people.
This is what we know so far:
The southern hemisphere was hit hard, and it probably is too
As the innumerable stories about the flu season have reminded him: every year, the The World Health Organization has to make a call about what should be included in the annual influenza vaccine. They look at how the virus has evolved so far, how it has spread, how effective the previous shots were, and so on until they make their best estimate. The influenza evolves so fast that the virus is usually quite different when it finally arrives in the USA. UU
Given that the southern hemisphere has its flu season a few months before us, it can sometimes be useful to observe how they have been doing it. This year is especially useful, because we are both using exactly the same vaccine. And so far, it has not looked good.
Australia has had a record number of cases and hospitalizations or deaths. A group of senior officials from the National Institutes of Health wrote a memorandum last week in New England Journal of Medicine warning US medical professionals. UU About the outbreaks. Our friends below had 215,280 cases in mid-October (towards the end of the flu season), which far outnumber the 59,022 cases they saw during the 2009 H1N1 pandemic. Part of the problem is that this year's vaccine is only 10 percent effective against the predominant flu strain in Australia.
Even in good years, we only achieve an effectiveness of between 40 and 60 percent. No vaccine is perfect. But because collective immunity helps keep the virus at bay to some degree, having a particularly low success rate means that many more people will get sick and die.
So far, there are more cases than normal
The Centers for Disease Control is a whole division dedicated exclusively to the monitoring of influenza. They monitor a number of different metrics, trying to discover how the season unfolds with the hope that they can help the nation prepare better.
At this time, we are seeing a spike in what is called "influenza-like illness," (ILI) plus a wider geographical spread than in previous years, ILI quantifies how much influenza activity we are seeing in a state , as measured by the number of cases more than the average number of people with flu-like symptoms, that means temperatures over 100 ° F plus a cough and / or sore throat, isolated but severe outbreaks can sometimes bias this metric, even if the rest of the state is having a quiet season, that's where geographic dispersion comes in. It does not measure gravity, but it shows how widespread the virus actually is.
Each one is a metric useful, and at this time both seem to indicate more than -activity average of the flu.
Here we show the geographical data so far this season compared with the last two. Ro 47, is the last week of November, which is the latest information available.
Part of the way the CDC determines when the flu season is officially is when we are above the ILI reference level. For most of the year, 2.2 percent of outpatients (those who are not hospitalized, basically) have a flu-like illness, that's the baseline. We do not confirm influenza with any type of test, so the flu-like illness is a substitute for knowing how many people have the flu at any given time. And as of the week of Thanksgiving, we're at 2.3 percent.
That puts us several weeks before the last two flu seasons, and a week before the 2014-15 season. Some weeks do not sound like much, but since the flu vaccine takes a few weeks to activate, it is crucial that people prepare now for what might be coming.
"At this point, I'm willing to say I'm looking forward to a season of early flu," says Richard Zimmerman, professor of family medicine at the University of Pittsburgh and director of PittVax, a CDC-funded team that evaluates the effectiveness of the flu vaccine. He is seeing more cases in his office than is normal at this time of year, in addition to closely monitoring the FluView of the CDC.
"We are seeing some kind of early increase in ILI," says Lynnette Brammer, director of the CDC's internal division influenza surveillance team. "The percentage of outpatient visits is higher than what we've seen during the same weeks since the 2010-11 season, but it's only one to two weeks."
Explain that comparing the seasons can be helpful in detecting some patterns, but if she learned something from influenza surveillance, the virus can always surprise you. This season may have had an early start, but it could reach stagnation and not be worse in the end than any other year. Or we could be in a particularly unpleasant season. It is too early to say it.
There is still some hope, but only if the virus changes in very particular ways
According to the unpredictability of the flu season, it is always possible that the influenza that hits EE. UU It is predominantly a strain directed by the vaccine. The H3N2 viruses led the unpleasant season in Australia, but if other varieties dominate here, we may save ourselves. We simply will not know until it is already happening.
By the time the influenza virus circumnavigates the planet each year, it has become a completely new demon, so we need a new vaccine every year. It is less predictable how much will change in the span of a few months. Global travelers can sometimes bring almost unchanged viruses to half the world, or a more gradual spread may allow them to mutate more dramatically. As more cases arise, researchers can sequence viruses to see which strains are most active, and can compare the virus on which the vaccine is based with those that are actually circulating. Unfortunately, all this happens after most people (thankfully) have been vaccinated, so it's too late to do anything about it, except to advise everyone to take extra precautions to stay healthy.
Still should be vaccinated against the flu, even if it is not effective could be
The reality of the flu is that even a vaccine below normal is better than any vaccine, especially on a population scale. Even if the injection is 10 percent effective, that does not mean it's 10 percent effective for you . The vaccine can still help your body fight part of the virus, which decreases symptoms and makes it less likely to be hospitalized, and may even help you avoid getting completely sick. It can also be totally ineffective. The problem is that you do not know what it will be until after they vaccinate you, and even if you do not like needles or doctors or stab you in the arm, it is better to get vaccinated and take an injection (pun). In a healthy winter you skip it.
It is helping to prevent the general spread of influenza by receiving the vaccine. Your grandparents and elderly neighbors are less likely to die of influenza if more people have even low levels of immunity. Help them to. Help himself. Get vaccinated