It is the time of year again when pharmacies and clinics provide flu shots, hospitals get ready for a surge of ill patients, and caregivers of young children and the elderly brace themselves for a winter of coughs, fevers andnbsp;sniffles.
Precisely how awful will the coming flu season be? It is a question that eludes even the specialists. Since influenza viruses are constantly changing, the seriousness and time of each season are notoriouslynbsp;unpredictable.
“I have been in this business long enough to know it’s harmful to make flu predictions,” says Danuta Skowronski, epidemiology cause flu and emerging respiratory pathogens in the BC Centre for Disease Control, that has been analyzing the flu for about 20nbsp;years.
Yet even though they warn it is too early to tell how the season will pan out, specialists like Skowronski are keeping a close eye on a few important things, including indicators of which influenza strain will be most widespread, and how successful this season’s flu shot willnbsp;be.
Here Is What to watchnbsp;for:
Which influenza strain will benbsp;overriding?
Influenza viruses are grouped into many distinct kinds, but when speaking to seasonal influenza, it is the B and A types which are the primary culprits. For influenza A, the subtypes that public health specialists are tracking carefully are H3N2 andnbsp;H1N1.
Both of these sorts of flu A viruses have quite different profiles, Skowronski states. Flu seasons where H3N2 is overriding are far more severe, characterized by a larger number of hospitalizations andnbsp;deaths.
H3N2 also tends to strike seniors toughest, whereas in H1N1 seasons, more kids and younger adults are generally affected, and there are normally fewer hospitalizations and fewer deaths, says Bryna Warshawsky, medical director of communicable disease, emergency preparedness and response at Public Healthnbsp;Ontario.
What we have experienced over the last couple of years is an alternating pattern in influenza A subtypes, Warshawsky says. Last year was an H3N2 season, and the year before was an H1N1 season. This was preceded by an H3N2-dominant flu season and an H1N1 season the year before that, shenbsp;states.
If this pattern holds, we could have a milder H1N1 flu season. The trouble is there is no telling if the routine willnbsp;persist.
What’s going to be the fallout in the summer flu season in the southern hemisphere?
Countries in the southern hemisphere, such as Australia and South Africa, have experienced a relatively severe flu season because of H3N2 over the summertime, Skowronski says. Hong Kong has also had a particularly long and deadly epidemic. Based on what has been happening in different areas of the planet, there has been much speculation that Canada will probably experience a serious epidemic,nbsp;also.
However, Skowronski says many are overlooking the fact that Canada already had a rather severe H3N2 outbreak last winter. “So the question is: Are [the other nations] following us? Or will we be after them?” shenbsp;says.
In any event, a major question is whether we have sufficient immunity one of our population to maintain whatever continuously changing flu variants are circulating at bay, shenbsp;states.
Warshawsky says it’s hard to make solid predictions for our flu season depending on the experience of other nations, because they vary from country to country. Australia, for example, she says, was struck by influenza A and influenza B in exactly the exact same time, which generated a big burden on its health-care system, whereas both flu types do not typically overlap in Canada. “We usually tend to see flu A first, and influenza B after,” she says. “So all of this makes what happened in other nations hard to find out how that may impact usnbsp;today.”
How successful will this year’s influenza vaccinenbsp;be?
Each year, around February or March, the World Health Organization provides its recommendations about the composition of influenza vaccines for the northern hemisphere for the next flu season, according to its projections of what viruses are most likely to be in flow. But it’s tough to predict precisely how successful the vaccines willnbsp;be.
Generally speaking, influenza vaccines are around 50 percent effective. However, for the 2014-15 season, the vaccine efficacy against H3N2 was less than 10 percent. Flu shots are by no means ideal, but they are still considered the best method of protecting individuals from gettingnbsp;ill.
The trivalent flu vaccine given this season, which comprises three elements, is comprised of an H1N1 vaccine component, an H3N2 component, and an influenza Bnbsp;element.
While the H1N1 component in this year’s flu shot has been updated for the coming season, the other two elements have remained unchanged from last year’s flu vaccine, Skowronski states. Based on which is the dominant strain this season, this may spellnbsp;trouble.
“If it turns out to be a H3N2 season, then that means the vaccine efficacy is very likely to be suboptimal,” she says. That’s because this past year, with precisely the same component, the vaccine efficacy for H3N2 was approximately 35 to 40 percent. And because the viruses are constantly changing and mutating, Skowronski says it is unlikely the potency of the identical vaccine component is going to be any higher for the forthcoming season. “That is one of those unfortunate, concerning variables, frankly, from my perspective: the H3N2 component is unchanged, yet we know the virus isnbsp;shifting.”
Nevertheless, just because this year’s flu shot comprises two from three of the exact elements as last year, do not think you won’t have to get vaccinated again if you have the shot this past year. The upgraded influenza B component can help protect you in an influenza B outbreak, Warshawsky says. Plus, she adds, “We also know that the length of protection does not necessarily last well from 1 year to another. So relying on last year’s vaccine won’t necessarily carry more security to thisnbsp;year.”
What impact do previous flu vaccinations have on the present flunbsp;shot?
It is a subject of debate, but there could be some reason to suggest that getting flu vaccines year after year could reduce their effectiveness. Skowronski says emerging data seems to indicate flu vaccines might not work too in people who have had repeat flu shots in prior years, compared with those vaccinated for the firstnbsp;time.
Since these findings are still emerging, researchers do not have any conclusive information regarding the mechanics to explain why this could be, Skowronski states. But one theory is that a preexisting antibody in those who’ve had previous flu shots could be “mopping up” or interfering with the antigens they get in the current year’s flu shot, ” she says. It might be that a new flu shot refocuses a preexisting antibody to target elderly antigens as opposed to currentnbsp;antigens.
“If it is a real phenomenon, which replicate immunization effect may play a role this season with [the] unchanged H3N2 vaccine component,” she says. If it turns out to be a H3N2 season, people who obtained last year’s flu shot might wind up being less protected by this year’snbsp;vaccine.
Nevertheless, there is not yet enough evidence concerning this potential effect to change public health policy, Skowronski states. And she highlights in most seasons, flu shots still provide better protection to people who’ve had prior flu vaccinations compared to those that aren’t vaccinated in any way. So you are better off getting the flu shot than not, even if you were vaccinated lastnbsp;year.
Some researchers dispute whether the result is real in the first location. Warshawsky and her colleagues conducted a systematic review and meta-analysis, published earlier this year in the journal BMC Medicine, that found no evidence that before flu shots lower the effectiveness of vaccinations. She states differences in research methods could explain why some studies have foundnbsp;differently.
In any event, researchers will be monitoring the efficacy of the year’s flu vaccine, which might help contribute to their comprehension of what is goingnbsp;on.
What job do vaccination ratesnbsp;drama?
In regards to the flu vaccine, it is hard to achieve herd immunity, that’s the protective effect of having a large proportion of the population immunized from a contagious illness, Warshawskynbsp;states.
Unlike other vaccines, such as the measles, mumps and rubella vaccine (MMR), which is about 97 percent effective at After two doses, the influenza vaccine is typically only about 50 percent effective. Additionally, it must be given yearly. Plus, each year, only around 30 percent of the populace generally gets vaccinated for thenbsp;influenza.
What is important to notice is if you do not get the flu, you won’t pass it on to anybody else, Warshawsky says, so on a single level, protecting yourself with a flu shot helps protect those around you. “But on a population level, to find enough people vaccinated to really stop flow [of a influenza virus], that is going to be more challenging tonbsp;reach.”
What is holding people back from gettingnbsp;vaccinated?
Vinita Dubey, associate medical officer of health at Toronto Public Health, cites what is called the “three Cs”: assurance, which involves people’s degree of confidence in vaccines, in vaccine producers, heath-care providers and the authorities; complacency, which entails a lack of understanding about the need for a vaccine or ambivalence about getting vaccinated; and advantage, or the simplicity of gettingnbsp;vaccinated.
Individuals who get flu shots are generally motivated not merely to protect themselves, but also to protect others, such as relatives, Dubeynbsp;states.
To encourage more people to get their yearly flu shots, ” she says public health officials attempt to target individuals in the community, school or childcare center level, as an example, by advocating that childcare workers get the flu shot not only for themselves, but for the children under their care, especially those under age 5 who are in highnbsp;risk.
In the institutional level, she says, some offices, like hospitals, have policies which require employees to get the flu shot or put on a mask during flu season. These steps probably affect people’s choice to get vaccinated, she says, noting that Toronto Public Health places the flu vaccination rates of certain offices, such as healthcare facilities, to promote those centers to urge their employees to receive their flunbsp;shots.
Dubey says Health Canada data indicates offering flu shots at pharmacies can bring about a small gain in the amount of people getting vaccinated. “So being able to provide it in various places isnbsp;useful.”
Should children get the nasal spray influenza vaccine?
For kids, the nasal spray FluMist has been provided as a pain-free method to obtain the flu vaccine. But there are conflicting recommendations about whether to usenbsp;it.
The U.S. Centers for Disease Control’s advisory committee on flu practices has recommended against using the nasal spray, which contains live attenuated flu, because of concerns about its efficacy. Alberta Health Services announced earlier this year it wouldn’t make FluMist accessible through the provincially funded influenza program this year. And Saskatchewan public health clinics will not be supplying the nasalnbsp;spray.
Bryna Warshawsky points out Canada’s National Advisory Committee on Immunization — that places the vaccination recommendations for the nation — states that for children aged 2 to 17, possibly a flu shot or nasal spray may benbsp;used.
The mixed messages about the nasal spray vaccine stem largely from conflicting U.S. and Canadian data. Canadian and some European research results show somewhat higher rates of efficacy for the nasal spray compared to U.S. results, states Warshawsky, medical director of communicable disease, emergency preparedness and response at Public Health Ontario. But the main reason for the difference is unclear. “People do not really know,” shenbsp;states.
“It is really a matter of talking to your health-care supplier to determine if there is any reasons you shouldn’t get one or another … and the preferences of the parents and the child,” shenbsp;states.
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Courtesy: The Globe And Mail