Biography of a virus
September 13, 2009
You push, you lean, you grab … and then you wonder how many other people have touched those same office doors and train poles today.
All the hype around swine flu, caused by the H1N1 virus, might make it difficult to feel safe as you go about ordinary life this fall, especially if someone near you is showing the slightest signs of being sick — a runny nose or red eyes.
School, city and world communities have the flu under a critical spotlight. Thankfully there has not been a single case of swine flu diagnosed on Columbia’s campus, but we should still be concerned. How concerned is the question, as facts surrounding the virus are easily confused.
For starters, the sheer volume of names for this virus can be mystifying: Swine flu, H1N1, a novel strain. It’s all of the above.
Pigs are indeed a reservoir for this virus, which is where the swine part comes from. But obviously humans can obtain this virus as well, and Dr. Stephanie Black at the Chicago Department of Public Health says birds can also carry it.
Speculating on why the original term swine flu has given way in the media, Dr. Blair Odland, an internist at the Columbia Health Center said, “Probably just politically the name was changed, so that people wouldn’t think of it as something to do with pigs. It has very little to do with pigs, actually.”
H1N1 is the scientific name of the virus. Technically, a virus is not considered a living organism but feeds off living bodies by invading cells. We call this invasion an infection, and to launch it, all viruses have cellular mechanisms that allow them to enter and leave cells. These are called hemagglutinins (the H factor) and neuraminidases (the N factor).
“The hemagglutinin is a surface attachment spot … on the surface of the viral capsule,” Odland said. “If you are catching a flu, that’s where the virus attaches.”
“The neuraminidase is used by the virus as an exit enzyme, which allows [the virus] to break out of the infected cell and spread to other cells in the body,” Odland explained.
This makes a virus contagious, which is vital to the viral lifecycle.
In biology, shape determines function. Hemagglutinins can take one of 15 shapes and neuraminidases can take any one of nine. These H and N factors are important in the labeling of viral types, which vary according to these shapes. Odland said they represent points that medicine can use to prevent or fight a viral infection.
But the name H1N1 can be confusing because the seasonal flu that we get every year is also classified as H1N1.
The swine flu that threatens us this fall does not resemble the seasonal H1N1 flu or any of the swine influenzas of the past, and therefore it is also referred to as a “novel” strand.
“The swine flu comes out every now and then,” Odland said.
The Centers for Disease Control and Prevention web site, a good source of facts about swine flu, cites another case that happened in 1988 when a swine flu outbreak in pigs in Wisconsin infected a few people. No epidemic followed though, and many people who were exposed to the virus didn’t get sick at all.
The most recent mass outbreak of a swine flu occurred in 1976. According to an August article in the Journal of Infectious Disease, the nation’s response to the 1976 occurrence “involved the immunization of [approximately] 45 million persons over a 10-week period against an A (H1N1) influenza virus of swine origin that had initially infected soldiers at Fort Dix, N.J.”
The episode left an unnerving history because–though only one person died from the virus and it did not spread beyond the fort–those who were vaccinated were at an increased risk of developing Guillain-Barré Syndrome, a very rare paralytic disorder.
The JID article goes on to explain the number of GBS cases were unusually high and caused the inoculations
to be halted.
“The consensus at the time was that the number of GBS cases was in excess of background incidence and although background data on GBS incidences were not firm, a political decision was taken to end swine influenza vaccination.”
An original 1976 retrospective study showed the chance of developing GBS increased by approximately 87 percent among all those who were vaccinated, compared to those who were not. However, the JID article also reported that after 1976 “multiple studies have failed to demonstrate a significant link between GBS and influenza vaccination.”
“The wild card is that [the vaccine] is part swine and nobody really knows what led to those complications from the swine vaccine [in 1976],” Black said.
Black said states will be required to keep a tight record of who gets vaccinated and the CDC will monitor adverse events that happen among vaccine recipients. She stressed the importance of individuals to weigh their risk of developing swine flu with the low risk of developing GBS.
“The CDC is very aware that people are concerned about the safety, but the vaccine is produced in the same way as the seasonal vaccine,” Black said.
Still, the manufacturing of this year’s swine flu vaccine differs from that of the seasonal vaccine in that the need is immediate. The ongoing race to make a vaccine puts a lot of pressure on a process which Odland said normally takes a whole year.
The New England Journal of Medicine reported on Sep. 10 the production of a vaccine efficient after only one dose. Australian-based CSL Biotherapies prepared the vaccine “in embryonated chicken eggs with the same standard techniques that are used for the production of seasonal [vaccine],” reported
the NEJM article.
The vaccine was tested on healthy individuals aged 18 to 64 years. Bellberry Human Research Ethics Committee approved the study and because CSL is licensed to sell vaccine in the U.S., Chicagoans will most likely get this vaccine. Chicago Department of Public Health Spokesman Tim Hadac said the city hopes to administer vaccinations by mid-to-late October.
The good news is that the Southern Hemisphere made it through its flu season without the swine flu vaccine and with only a mild reaction to the virus in case numbers, case severity and duration of the outbreak.
There was also no sign of the virus mutating, which is a huge concern as The Chronicle reported this May that influenza viruses mutate even faster than the human immunodeficiency virus that causes AIDS, also known to mutate very quickly.
When the U.S. government put out scary numbers of possible scenarios for deaths and hospitalizations, Black gave some insight and said, “They test really severe hospitalized cases so you get this false sense that everything is really severe.”
While the wait for the vaccine goes on, Columbia remains a potential hot-spot for the illness. Preparations for a severe flu breakout remain a high priority for the college, city and nation.
tgleason@chroniclemail.com