By Vincent Gabrielle
BU News Service
SPRINGFIELD — Baystate Health announced this week it was tightening visitor access to prevent the spread of the flu. Reports from Australia indicate the flu vaccine is only 10 percent effective against influenza A (H3) and 33 percent effective overall this year. The Centers for Disease Control and Prevention report the flu season peaked in the United States several months earlier than usual. There have been comparisons to the 2009 swine flu pandemic.
With all this information swirling, it’s understandable people might be concerned. Public health experts are also concerned, but they advise caution and perspective.
Dr. Alfred DeMaria, medical director and state epidemiologist for the Massachusetts Department of Public Health, stressed that while this year’s flu is bad, it is far outside the range of a pandemic.
“2009 was a pandemic. This is a bad flu season,” DeMaria said. “It’s like comparing apples and oranges.”
Influenza is a respiratory virus that causes fever, coughing, muscle pain, fatigue and headaches. Less commonly, it can cause nausea and stomach pain.
Influenza is usually mild but may cause severe infections and fatalities. The infamous 1918 influenza pandemic infected approximately 500 million people worldwide and killed 50 to 100 million according to the Center for Disease Control and Prevention. It was responsible for more deaths than World War I which was happening at the same time.
The virus spreads annually during the respective winters in the Northern and Southern hemispheres. Cold, dry and dark winters promote the spread of flu. Dry air also dries out protective respiratory mucus.
The cold keeps you indoors and near other people. The lack of sunlight also means less UV which kills viruses. It’s perfect for transmission.
In the United States, the flu season runs from October until the following May, peaking in February. This year’s flu is unusual. It began to peak in December during the holiday season.
It’s unclear why this occurred, but it may have increased the transmission of flu this year, contributing to a worse season.
“Nothing indicates this year’s virus is more virulent than last year’s,” DeMaria said. “It headed toward a peak during the holidays when everybody was congregated and off work. That could have contributed to making it worse.”
DeMaria also stressed holiday travel could have contributed to spreading the flu.
What about rumors the flu vaccine is ineffective or causing the flu?
Dr. Brian Chow, an infectious disease physician at Tuft’s Medical Center, said those claims are based on studies conducted in Australia on the southern vaccine.
Influenza comes in three main types, A, B and C. Type A is known for having different surface antigens (H and N) which have many different numbered variants that can recombine (like H3 N2 or H1N1). Each type of flu virus also propagates into numerous strains that are subtly different from each other.
Vaccines are only effective against specific strains and serotypes.
To build a vaccine, scientists grow influenza in eggs or cell culture that they predict will match the influenza in the wild. They then kill these viruses and use them in the vaccines. By showing your immune system dead viruses, you can protect against future infections.
This means each vaccine contains multiple types of influenza. The newest vaccine contains up to four types. The southern vaccine, which wasn’t effective against H3N2, contains different strains and was manufactured differently than the vaccines used in the U.S.
“The vaccine strain drifted during the manufacturing process,” Chow explained. “When it was released, it was not a good match for the strain circulating in the wild.”
So, the vaccine is effective?
“The flu vaccine is still the best tool we have to prevent influenza,” Chow said. “Studies show even if you get the flu after being vaccinated, you’re less likely to be hospitalized or develop severe complications.”
The flu vaccine is also more effective against influenza B which tends to peak later in the season. Doctors stress it isn’t too late to get vaccinated.
“Right now, it is not too late to get the vaccine if you haven’t already – there are still many weeks of the flu season remaining,” Dr. Graham Snyder, associate epidemiologist at Beth Israel Medical Center, wrote in an email.
Snyder wrote that it is most important to wash your hands often and avoid going to work or class when sick.
Most importantly, Snyder wrote, get vaccinated.