Alex Kurland, Staff Illustrator
As midterms wind down, this year’s flu season has secretly approached its final days. Even though those annual aches and colds might be behind most of us, there are others who are hard at work, already preparing for next year.
The medical community has to start early if it wants to stay ahead of the yearly flu epidemic. Part science, part prediction, the development of an up-to-date flu vaccine is an international effort.
Scientists discovered the influenza virus in the 1930s when ferrets used for research transmitted the virus to their keepers. The resulting first vaccine used inactive virus as opposed to a weakened live strain and when it was tested in animals, found a protective response. The vaccine was eventually licensed in the 1940s.
Even though the vaccine showed protection, it’s difficult to know its actual effectiveness. One can get the flu vaccine nearly anywhere; this makes it difficult to collect data outside of asking individuals who often don’t remember whether they’ve received the flu vaccine or not.
Also, since the flu is traditionally not a reportable illness, a considerable amount of guessing must go into the total number of estimated flu cases every year, let alone an accurate number of cases among the vaccinated population. For this reason, specific randomized studies often do not yield conclusive results because sampling is so difficult. Broad epidemiological studies and community comparisons are the main source of information.
John Treanor is the chief of the department of infectious diseases at the University of Rochester Medical Center (URMC) and works closely with the influenza virus.
This past season was a “relatively more active year,” according to Treanor. H3N2, a strain that manifests more frequently in elderly patients, was especially prevalent this year, and since elderly patients are more likely to go to the hospital and eventually die of complications, it’s difficult to attribute a death count directly to the flu or measure the success of this year’s vaccine.
“We don’t know as much about these respiratory infections as others,” Treanor said.
This year in particular, they were unsure, but there is a preexisting history of this uncertainty, especially among elderly patients.
“We don’t know why it didn’t work as well this year,” he said. “We never know for sure.”
Well, why do we insist on a flu vaccine every year if we’re not sure they even work? Despite all of the ambivalence and uncertainty with actual success rates, there is no doubt that the vaccine does its job, even if not perfectly.
“It works. You can always show that flu shot people contract the flu less,” Treanor said.
The general policy has been to promote the vaccine to the elderly and others who are susceptible to the flu and to err on the side of vaccination. According to the University Health Service (UHS), there was a 64 percent increase in students vaccinated on campus this past year. Even with the jump, only 23 percent of students were vaccinated. UHS also recognizes that these are minimum numbers since many students can get their flu shots elsewhere.
“As time goes on, we’ve become less sure of success, but there’s no downside to the vaccine,” Treanor explained. “There is definitely some protection, it’s cheap, and it’s completely safe. At the same time, though, we want something better.”
URMC is testing vaccines against potentially larger scale pandemics and researching the most effective ways to distribute them.
“Flu viruses are tricky,” Treanor said. “They will change their outer coat every year to cause an epidemic.”
The H-number-N-number naming system of the viruses refers to the two main proteins on this outer coat called hemagglutinin and neuraminidase. When making vaccines, matching these proteins is important. One flu vaccine doesn’t fit all, and if there is a large change from year to year, there can be an epidemic. That said, this matching process isn’t perfect either: It’s not black and white.
These year-to-year “subtle differences are hard to interpret,” but the World Health Organization (WHO) does its best, predicting next season’s strains with a process of intense surveillance and statistics.
“If they detect something that is substantially different, they must make a decision to change the vaccine,” Treanor explained. “This decision is made by February, usually, but they’re really just guessing which will be the next main strain.”
After the WHO decides the most likely strain, companies licensed to produce the vaccine get to work, churning out massive amounts in a short time.
“It’s a tough thing to do, to get the thing out the door in time,” Treanor added.
The yearly infections are due to small changes, but the big epidemics hit when radically different strains are introduced to human populations. These are usually transmitted from animals, but we’re not sure exactly how. The most common carrier is migratory birds that mingle with livestock and transmit the virus to humans via agriculture.
“That’s probably what happens,” Treanor said. “It’s unclear.”
Regardless, these new viruses can be dangerous.
“[They] have a huge advantage entering a new population,” he said. “They spread like wildfire.”
When a virus reaches humans, the problem becomes susceptibility. Normally, children are more susceptible than adults because their immune systems are less experienced with flu. When a new virus emerges, however, all bets are off.
“It’s like your immune system was a kid eating M&M’s, but just blue M&M’s,” Treanor explained. “You could have different shades, but they were always some kind of blue. Then, all of a sudden, you get a red M&M. You’re used to blue, but then it’s red. It’s like your first M&M all over again. Or, like you never had the flu before. That’s a pandemic.”
The flu may not seem like a major threat to humanity, but a widespread illness such as this could easily turn into a more serious threat.The race for a flu vaccine is a never-ending struggle, and unfortunately humans, specifically URMC and other immunology researchers, are the ones who must catch up.
Esce is a member of
the class of 2015.
