Unusual type of flu virus is dominating early start to this year’s flu season Get your flu shot if you haven't yet. BETH MOLE - 12/10/2019, 1:37 PM
A child received a vaccination against influenza A (H1N1). Enlarge / A child received a vaccination against influenza A (H1N1). Getty | BSIP 211 WITH 96 POSTERS PARTICIPATING SHARE ON FACEBOOK SHARE ON TWITTER The 2019-2020 flu season is up and running—and so far, it's off to a weird start.
Flu activity has been elevated since the start of November and is only expected to continue climbing, the Centers for Disease Control and Prevention reports in its latest flu update. That's a few weeks earlier thanin past years.
Flu season in the United States can ramp up in the fall and peak anywhere between December and March, then drag itself out as late as May. In the last36 years, flu most often ramped up in December and January and peaked in February. But for this winter, the CDC says there's a 40 percent chance the flu will peak in December based on activity so far.
While this season may peak on the early side, the most unusual aspect is that it's being driven by an influenza B strain. This isn't necessarily goodor bad, just unusual.
Type B is one of three types of influenza viruses that infect humans—A, B, and the very mild C. (There's a fourth type, D, but so far it mainly seems to infect cattle.) Most flu seasons are driven by type A viruses, the kind you've probably heard about the most. Type A viruses are identified by numbered Hs and Ns, like H1N1 and H3N2.
Viral code The Hs and Ns refer to hemagglutinin (Ha or H) and neuraminidase (Na or N), respectively, which are both viral molecules that hang on the outside of viral particles. Basically, Ha helps viral particles invade human cells in the respiratory tract and Na allows newly formed viruses to burst out of human cells and invade more (for more details, see this explainer). But, because they jut out from a viral particle, Ha and Na also help our immune systems identify flu virus. This essentially triggers an arms race.
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FURTHER READING Looks like a rough flu season ahead. Here are answers to ALL your flu questions Type A viruses can swiftly mutate and rearrange the molecular makeup of Has and Nas, making them difficult if not impossible for our immune systems to recognize. That's where the numbering comes in. There are 18 Ha subtypes and11 Na subtypes known, creating 198 possible combinations. To make things more interesting, type A viruses are promiscuous—they infect humans, many mammals, and birds. This gives them a lot of opportunities to swap their Hasand Nas and come up with exciting combinations. Occasionally, extremely dangerous combinations can spark pandemics, such as the deadly H1N1 "swine flu" that spread worldwide in the 2009-2010 flu season. The ever-morphing nature of type A viruses is the main reason why flu can be so deadly and whywe need to get different flu shots every season. Type B viruses—which are dominating this flu season so far—don't do any ofthis. Their Has and Nas genetically "drift" relatively slowly. Type B viruses also only infect humans and, oddly enough, seals, giving them fewer opportunities to mingle and rearrange themselves. Since type B viruses were first spotted in the 1940s, they have never been linked to a pandemic.
Instead of a soup of numbers, Hs, and Ns, type B viruses are mainly identified by their lineage. In the 1980s, geneticists noted that type B viruses seemed to have split into two distinct, evolutionary lineages based on studying their Has. They dubbed the lineages B/Victoria for a reference stain isolated in Australia and B/Yamagata after a reference strain isolatedin Japan.
Type B viruses typically account for about a third of all of the flu diseaseburden. For many years, researchers had the impression that they were relatively mild flu strains, given their slow evolution and limited host- hopping. But recent studies have found that they can cause severe disease and sometimes cause the bulk of flu-related deaths in a season. Type B viruses are also detected most often in children.
Latest data According to the latest surveillance data from US surveillance programs, around 60 to 70 percent of the flu viruses analyzed from patients this flu season have been type B viruses. Of those, about 97 percent tested were in the B/Victoria lineage. Over the last few weeks, the proportion of B/ Victoria strains among the flu-positive cases has been increasing.
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It's unclear why B/Victoria is surging or what that surge means for the restof the flu season. CDC spokesperson Scott Pauley told Ars over email that flu is difficult to predict and that it's simply "too early to make any kindof assessment about the potential severity of the season."
We should also note that cases of type B viruses have been relatively low inrecent years and almost non-existent in the 2018-2019 flu season. This may mean that there's less immunity in the population overall.
Some good news is that early testing suggests that most of those B/Victoria strains now roaring back are B/Colorado/06/2017-like (Victoria lineage), which are covered by this year's flu vaccine.
Otherwise, very small samplings of the type A viruses popping up this season—H1N1 and H3N2 viruses—suggest that they're nearly all similar to the A/ Brisbane/02/2018 (H1N1)pdm09–like virus and the A/Kansas/14/2017 (H3N2)– like virus, which are both covered by this year's flu vaccine.
Get vaccinated However, as CDC's Pauley noted to Ars, "there is relatively little laboratory data on the characterization of viruses collected since October, so it's not possible to make conclusions about how well the vaccine will work at this time."
There has been some concern that the flu vaccine recommended for the 2020 flu season in the Southern Hemisphere includes different H3N2 and B/Victorialineage viruses than the 2019-2020 vaccine for the Northern Hemisphere. But again, flu seasons are notoriously difficult to predict, and it's still too early to say what will happen.
Regardless of how well-matched this year's vaccine will be to circulating flu viruses, getting a flu shot is critical, Pauley notes to Ars. The vaccine can spare you entirely and prevent disease spread or, at least, dampen the severity of the infection, potentially saving lives. "Flu vaccination is the best way to reduce the risk from flu and its potentially serious complications," Pauley says.
So far in the US, there have been six confirmed pediatric deaths from flu this season. Overall, the CDC estimates that there have already been at least 1.7 million flu cases nationwide this season, leading to at least 16, 000 hospitalizations and 910 deaths. Southern states have been hardest hit.
The U.S. winter flu season is off to its earliest start in more than 15 years.
An early barrage of illness in the South has begun to spread more broadly, and there’s a decent chance flu season could peak much earlier than normal, health officials say.
Some experts think the early start may mean a lot of suffering is in store, but others say it’s too early to tell.
The U.S. winter flu season is off to its earliest start in more than 15 years.
An early barrage of illness in the South has begun to spread more broadly, and there’s a decent chance flu season could peak much earlier than normal, health officials say.
The last flu season to rev up this early was in 2003-2004 — a bad one. Some experts think the early start may mean a lot of suffering is in store, but others say it’s too early to tell.
“It really depends on what viruses are circulating. There’s not a predictable trend as far as if it’s early it’s going to be more severe, or later, less severe,” said Scott Epperson, who tracks flu-like illnesses for the U.S. Centers for Disease Control and Prevention.
There are different types of flu viruses, and the one causing illnesses in most parts of the country is a surprise. It’s a version that normally doesn’t abound until March or April.
That virus generally isn’t as dangerous to older people — good news, since most flu hospitalizations and deaths each winter occur in the elderly. However, such viruses can be hard on children and people younger than 50.
Louisiana was the first state to really get hit hard, with doctors there saying they began seeing large numbers of flu-like illnesses in October.
刚听21.02.09【觀點│唐湘龍時間】1.誰說中國隱匿疫情？滾出來！2沒錯！我就是少
康幫！
唐湘龙说2019年美国是第一参加武汉军运会，派了100多人啊！没有拿到任何奖牌，中
间那个被怀疑零号病人女自行车手，居然有52岁了！美国什么时候缺自行车运动员了？需要派个52岁的老将去？所以去下毒才是首要任务吧？派军人干这事是合适的，这就是战争嘛！据说这些军人都是坐专机回去的，这是隔离吧？
难怪川普蓬佩奥口口声声中国病毒呢，这是要恶人先告状，想把污水泼到中国头上，让中国在忙于对抗疫情时无暇分辨！
WHO专家们的结论是中国是受害者！多么清晰明了啊！我等着看全世界要求彻查美国马
里兰实验室，要求美国赔偿！
中国是真正的受害者，因为美国就是故意去武汉散播病毒的！
可怜啊，没人附和这个五矛。
给点面子附和一下。 可能真的是美国老军人带过去的。 美国人做事太认真了，投个毒都要动用几百人和专机。 几块冻猪肉就能解决的问题。
什么叫第一次参加武汉军运会，武汉军运会就一次，所有国家都是第一次参加武汉军运会。之前军运会在其他国家轮流举办，美国也有参加。
这是明摆着的，
否则武汉军运会不会专门声明：谁敢侵犯我们就叫他灭亡！
比较合理的解释是有情报显示武汉可能病毒泄漏不安全， 所以美方派了些闲杂人员参
与了军运会。
12/10/2019 Unusual type of flu virus is dominating early start to this year
’s flu season
http://arstechnica.com/science/2019/12/this-years-flu-season-is-off-to-an-
early-unusual-start-cdc-says/
Unusual type of flu virus is dominating early start to this year’s flu
season
Get your flu shot if you haven't yet.
BETH MOLE - 12/10/2019, 1:37 PM
A child received a vaccination against influenza A (H1N1).
Enlarge / A child received a vaccination against influenza A (H1N1).
Getty | BSIP
211
WITH 96 POSTERS PARTICIPATING
SHARE ON FACEBOOK
SHARE ON TWITTER
The 2019-2020 flu season is up and running—and so far, it's off to a weird
start.
Flu activity has been elevated since the start of November and is only
expected to continue climbing, the Centers for Disease Control and
Prevention reports in its latest flu update. That's a few weeks earlier thanin past years.
Flu season in the United States can ramp up in the fall and peak anywhere
between December and March, then drag itself out as late as May. In the last36 years, flu most often ramped up in December and January and peaked in
February. But for this winter, the CDC says there's a 40 percent chance the
flu will peak in December based on activity so far.
While this season may peak on the early side, the most unusual aspect is
that it's being driven by an influenza B strain. This isn't necessarily goodor bad, just unusual.
Type B is one of three types of influenza viruses that infect humans—A, B,
and the very mild C. (There's a fourth type, D, but so far it mainly seems
to infect cattle.) Most flu seasons are driven by type A viruses, the kind
you've probably heard about the most. Type A viruses are identified by
numbered Hs and Ns, like H1N1 and H3N2.
Viral code
The Hs and Ns refer to hemagglutinin (Ha or H) and neuraminidase (Na or N),
respectively, which are both viral molecules that hang on the outside of
viral particles. Basically, Ha helps viral particles invade human cells in
the respiratory tract and Na allows newly formed viruses to burst out of
human cells and invade more (for more details, see this explainer). But,
because they jut out from a viral particle, Ha and Na also help our immune
systems identify flu virus. This essentially triggers an arms race.
Advertisement
FURTHER READING
Looks like a rough flu season ahead. Here are answers to ALL your flu
questions
Type A viruses can swiftly mutate and rearrange the molecular makeup of Has
and Nas, making them difficult if not impossible for our immune systems to
recognize. That's where the numbering comes in. There are 18 Ha subtypes and11 Na subtypes known, creating 198 possible combinations. To make things
more interesting, type A viruses are promiscuous—they infect humans, many
mammals, and birds. This gives them a lot of opportunities to swap their Hasand Nas and come up with exciting combinations. Occasionally, extremely
dangerous combinations can spark pandemics, such as the deadly H1N1 "swine
flu" that spread worldwide in the 2009-2010 flu season. The ever-morphing
nature of type A viruses is the main reason why flu can be so deadly and whywe need to get different flu shots every season.
Type B viruses—which are dominating this flu season so far—don't do any ofthis. Their Has and Nas genetically "drift" relatively slowly. Type B
viruses also only infect humans and, oddly enough, seals, giving them fewer
opportunities to mingle and rearrange themselves. Since type B viruses were
first spotted in the 1940s, they have never been linked to a pandemic.
Instead of a soup of numbers, Hs, and Ns, type B viruses are mainly
identified by their lineage. In the 1980s, geneticists noted that type B
viruses seemed to have split into two distinct, evolutionary lineages based
on studying their Has. They dubbed the lineages B/Victoria for a reference
stain isolated in Australia and B/Yamagata after a reference strain isolatedin Japan.
Type B viruses typically account for about a third of all of the flu diseaseburden. For many years, researchers had the impression that they were
relatively mild flu strains, given their slow evolution and limited host-
hopping. But recent studies have found that they can cause severe disease
and sometimes cause the bulk of flu-related deaths in a season. Type B
viruses are also detected most often in children.
Latest data
According to the latest surveillance data from US surveillance programs,
around 60 to 70 percent of the flu viruses analyzed from patients this flu
season have been type B viruses. Of those, about 97 percent tested were in
the B/Victoria lineage. Over the last few weeks, the proportion of B/
Victoria strains among the flu-positive cases has been increasing.
Advertisement
It's unclear why B/Victoria is surging or what that surge means for the restof the flu season. CDC spokesperson Scott Pauley told Ars over email that
flu is difficult to predict and that it's simply "too early to make any kindof assessment about the potential severity of the season."
We should also note that cases of type B viruses have been relatively low inrecent years and almost non-existent in the 2018-2019 flu season. This may
mean that there's less immunity in the population overall.
Some good news is that early testing suggests that most of those B/Victoria
strains now roaring back are B/Colorado/06/2017-like (Victoria lineage),
which are covered by this year's flu vaccine.
Otherwise, very small samplings of the type A viruses popping up this season—H1N1 and H3N2 viruses—suggest that they're nearly all similar to the A/
Brisbane/02/2018 (H1N1)pdm09–like virus and the A/Kansas/14/2017 (H3N2)–
like virus, which are both covered by this year's flu vaccine.
Get vaccinated
However, as CDC's Pauley noted to Ars, "there is relatively little
laboratory data on the characterization of viruses collected since October,
so it's not possible to make conclusions about how well the vaccine will
work at this time."
There has been some concern that the flu vaccine recommended for the 2020
flu season in the Southern Hemisphere includes different H3N2 and B/Victorialineage viruses than the 2019-2020 vaccine for the Northern Hemisphere. But
again, flu seasons are notoriously difficult to predict, and it's still too
early to say what will happen.
Regardless of how well-matched this year's vaccine will be to circulating
flu viruses, getting a flu shot is critical, Pauley notes to Ars. The
vaccine can spare you entirely and prevent disease spread or, at least,
dampen the severity of the infection, potentially saving lives. "Flu
vaccination is the best way to reduce the risk from flu and its potentially
serious complications," Pauley says.
So far in the US, there have been six confirmed pediatric deaths from flu
this season. Overall, the CDC estimates that there have already been at
least 1.7 million flu cases nationwide this season, leading to at least 16,
000 hospitalizations and 910 deaths. Southern states have been hardest hit.
DEC 6 20194:55 PM EST Flu season arrives early, driven by an unexpected
virus
https://www.cnbc.com/2019/12/06/us-flu-season-arrives-early-driven-by-an-
unexpected-virus.html
Key Points:
The U.S. winter flu season is off to its earliest start in more than 15
years.
An early barrage of illness in the South has begun to spread more broadly,
and there’s a decent chance flu season could peak much earlier than normal, health officials say.
Some experts think the early start may mean a lot of suffering is in store, but others say it’s too early to tell.
The U.S. winter flu season is off to its earliest start in more than 15
years.
An early barrage of illness in the South has begun to spread more broadly,
and there’s a decent chance flu season could peak much earlier than normal, health officials say.
The last flu season to rev up this early was in 2003-2004 — a bad one. Some experts think the early start may mean a lot of suffering is in store, but others say it’s too early to tell.
“It really depends on what viruses are circulating. There’s not a
predictable trend as far as if it’s early it’s going to be more severe, or later, less severe,” said Scott Epperson, who tracks flu-like illnesses
for the U.S. Centers for Disease Control and Prevention.
There are different types of flu viruses, and the one causing illnesses in
most parts of the country is a surprise. It’s a version that normally doesn’t abound until March or April.
That virus generally isn’t as dangerous to older people — good news, since most flu hospitalizations and deaths each winter occur in the elderly.
However, such viruses can be hard on children and people younger than 50.
Louisiana was the first state to really get hit hard, with doctors there
saying they began seeing large numbers of flu-like illnesses in October.
铲逼不明白为什么美军不派派奥运冠军参加军运会。