Originally published Dec. 18, 2014
United States health officials are warning the flu vaccine may not be fully effective in preventing the spread of disease due to changes in this season’s most common strain of flu virus, the U.S. Centers for Disease Control and Prevention announced Dec. 3.
A health advisory released by the CDC to healthcare providers announced that the nation is seeing a rise in flu cases caused by influenza A (H3N2), one of the largest strains of influenza virus. The advisory stated that a little more than half of viral specimens tested were antigenically different from the H3N2 virus component present in this season’s vaccines. This means the vaccine does not specifically protect against the exact strain of virus now most commonly circulating.
The culprit? Antigenic drift, small changes in the genes of flu viruses which occur over time as the virus continually replicates, according to the CDC. Over time, a person’s antibodies will no longer be effective against the virus, and so the person could again become sick. This year, the H3N2 strain has drifted from the strain present in the vaccine, so the antibodies created by the vaccine will not provide the same protection that they would have.
More than 144 million people have received flu vaccines this year, according to CDC reports. This means millions could still be susceptible to the illness that causes fever, chills, cough, sore throat, runny nose, headaches, muscle and body aches, fatigue and, in severe cases, death.
It is spread by coughing, sneezing and coming into contact with the droplets produced by these activities, according to the CDC. It is recommended anyone over the age of six months be vaccinated unless they have an egg allergy or have had adverse reactions in the past, according to Dr. Sheila Pinette, director of the Maine Center for Disease Control and Prevention.
Pinette says this type of circumstance is not unusual because the strains of flu included in the vaccine are decided by the World Health Organization toward the end of the previous flu season. This proves to be problematic as the virus can change from when the strains are selected in February to when the vaccine is made available to the public in August.
Pinette says WHO became aware of possible changes to the viruses in March of this year, but couldn’t do anything because production of the vaccine had already begun.
News of H3N2 drift casts a shadow over the anticipated success of a new vaccine formulation. This new formulation, called a quadrivalent vaccine, contains four flu viruses as opposed to the traditional trivalent option, which only contains three. It was hoped that this new vaccine would offer enhanced protection from the flu, but recent numbers indicate that the flu will remain a national health concern in coming months.
Between Nov. 29 through Dec. 6, the federal CDC reported 3,415 new positive flu specimens, more than 3,200 of which were influenza A viruses. Of these, more than 90 percent were H3N2 types. As of Dec. 6, there more than 8,800 confirmed positive flu specimens in the U.S.
As of Dec. 13, there have been 121 confirmed positive specimens of flu in Maine, 47 more since the previous week’s report. Most cases are in Cumberland and Penobscot counties.
However, the number of confirmed flu cases in Maine and the nation could be much higher than what is currently known.
“Influenza itself is not reportable, so the only reports we have are labs and providers who are willing to submit,” said Sara Robinson, epidemiologist with the Maine CDC.
With this thought, many people are bracing for what could become a severe flu season. The U.S. CDC said in a press release that early data suggests the 2014-2015 flu season has the potential to become severe and urged immediate vaccination for those who have not done so already.
“It’s too early to say for sure that this will be a severe flu season, but Americans should be prepared,” Dr. Tom Frieden, director of the CDC said in the press release.
“Our feeling is you can never expect the unexpected, but we have to be prepared. Part of our prevention is making sure we’re educating providers, sending out these health alerts and just preparing for the worst,” Pinette said.
Part of the uncertainty of this year’s flu season is due to the unpredictability of the influenza A viruses.There are two proteins that determine the strain of flu — the H and the N — and there are many different forms each protein, according to the CDC. As a result, the virus can change into a multitude of different strain types.
“There’s a lot of H’s and a lot of N options, and they all kind of play around with each other and they mutate a lot, so we never know when we’re going to get a combination that’s bad,” Robinson said.
As of right now, the H3N2 virus has not mutated into a new strain of flu, Robinson said. Instead, it has merely drifted from the form included in the vaccine into a different, but still antigenically similar subtype. Because the virus is still similar, the vaccine may offer cross-protection from the flu, which will likely lessen the severity of symptoms, Pinette said.
Flu outbreaks tend to occur most often at institutions like long-term care facilities and college campuses. In light of the recent drift of influenza H3N2, some University of Maine students voiced their opinions regarding the flu vaccine.
“I get [the vaccine] because I don’t want to get sick,“ said Emma Hardy, who studies communication sciences and disorders at the university. “I feel people probably don’t get [vaccinated] because they probably think they’re not going to be the person to get the flu.”
But others were not as supportive of universal vaccination protocol.
“I don’t really worry about it,” said Daniel Norwood, a history and political science student at the university, when asked if concerned about the flu. “I don’t really give it a second thought,” he said. “I don’t get sick that often.”
“I don’t get the shot because it doesn’t fight against all strains of flu,” said electrical engineering major Kati Burdet, who for seven years worked at Redington Fairview General Hospital in Skowhegan.
Burden stated that after the two times she got a flu vaccine she became sick. “I think it’s a very controversial issue because most hospitals require you to get a flu shot if you’re an employee there,” she said. “I think it’s a personal choice.”
Still, Dr. Pinette stresses that vaccination is the cornerstone of treatment.
“The more people that get immunized the better we will be preventing spread within our communities,” she said.
“Mutations occur regularly with the influenza virus,” Robinson said. “That is why it is important to get vaccinated each year because the circulating strains change rapidly.
Some mutations are worse than others,” she said.
The CDC recommends good respiratory etiquette such as coughing or sneezing into the elbow or shoulder, frequent hand washing with warm soapy water, and staying home if sick as preventative measures to practice to avoid catching the flu.
The CDC also recommends that anyone who suspects they are sick with the flu should contact their doctor within 48 hours of becoming sick as this is the best potential time for treatment, although treatment can still be started after this period with lesser success. People with the flu are often treated with the antiviral drugs Oseltamivir and Zanamivir, which target the flu virus and stop its replication in the body.
Despite uncertainty about the severity of this year’s flu season, Pinette still stands by her stance that Maine is prepared for this flu season.
“Every year you can’t anticipate it,” she said. “We just have to go forward and be prepared.”
Featured image courtesy: By Photo Credit: Cynthia Goldsmith Content Providers(s): CDC/ Dr. Erskine. L. Palmer; Dr. M. L. Martin [Public domain], via Wikimedia Commons