Despite ‘Drift’ Flu Vaccine Remains Best Protection

Friday, December 12, 2014

This year’s flu season is underway in the Washington, DC metropolitan region, but early indications are it may not only be a tough one, but the flu vaccine will not be as effective as hoped.

Nevertheless, a vaccine is one of the best defenses against the flu.

“The CDC continues to emphasize that getting vaccinated is still the best way to prevent and combat flu. The overall effectiveness of the vaccine in our population may very well be lower this year because of the ‘drift’ but vaccinated individuals have a good chance of having ‘cross-protection’ against the circulating H3N2 strain,” Children’s National infectious disease specialist David Hyun, MD, said.

Health officials warn an aggressive influenza strain, H3N2 strain, has changed or mutated after vaccines were distributed and is currently widely circulating. And early data collected by the Centers for Disease Control and Prevention (CDC) suggest a harsher than normal flu. Changes or mutations in the strain may reduce the effectiveness of the flu vaccine.

"For each flu season, experts and epidemiologists have to make predictions 9-10 months in advance of what the most likely circulating strains will be,” Dr. Hyun said. “This is because it takes that much time for the vaccine manufacturers to accommodate those predictions/selections of the strain and have the vaccine products ready by August/September. So, for this flu season the experts made the selections of which strains should be targeted for protection in the vaccine all the way back in March."

Does The Vaccine Cover All Viruses?

The CDC is “expressing caution that the vaccines may not provide high levels of protection because of the differences between the circulating strain and the vaccine strain,” Dr. Hyun said.

Dr. Hyun said this isn’t unusual and changes in the circulating strains happen every few years.

“In past years, you may have heard news outlets describing, during the flu season, that the vaccine was ‘not a good match’ for the flu strains circulating. Basically it’s the same thing,” Dr. Hyun said.

A ‘Drift’ Doesn’t Mean Vaccines Are Useless

“None of the announcements have any implications for vaccine safety,” Dr. Hyun said. “Vaccine safety is still expected to be the same as before with the same contra-indications in place.”

Are There Any Universal Vaccines?

“Ideally we would love to have a vaccine that universally covers all strains and that is being researched,” Dr. Hyun said, adding that research indicates that “we may not be that far away from this becoming a reality.

“But in the meantime, we are still limited on how many strains we can provide protection for in a single vaccine,” he said.

The CDC warning is also important because some of the most severe flu seasons have occurred when the H3N2 strain was most prevalent.

Flu Vaccine Remains the Best Protection

It is still best to get vaccinated.

“It may have some genetic changes but it's still an H3N2 strain and continues to share many common genetic features with the vaccine H3N2 strain,” Dr. Hyun said. “This cross-protection may be enough to prevent a vaccinated individual from getting infected or even in infected individuals may provide enough immunity to temper the severity of the disease.”

Not Too Late to Vaccinate

The flu shot or nasal spray is the best tool for prevention.

“It's never too late to receive a flu vaccine during the flu season,” Dr. Hyun said.

Vaccination will protect against strains other than H3N2.

“Even if H3N2 is the predominant strain this season, there will still be a baseline level of H1N1 circulating as well and the vaccine can provide protection against it,” Dr. Hyun said. “In addition, you also get protection against the Influenza B strains which will circulate March once H3N2 fades out.

Ways to Avoid the Flu

Dr. Hyun said hand washing is the best prevention against the spread of germs. Stay home when sick. And properly cover your coughs. Learn more about how you can protect your family this flu season.

National Influenza Vaccination Week, which started Sunday and ends tomorrow, was established to focus attention on the importance of flu vaccines. The flu season typically lasts several months, peaking in January and February before ending in late winter or early spring.

Some of the flu-like symptoms to monitor in your kids include:
  • Fever
  • Cough
  • Sore throat
  • Body aches
  • Headache
  • Vomiting or diarrhea


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