A (flu) shot in the arm

When I rolled up my sleeve last week for my annual flu shot, I was given a new option: an intradermal injection, using a microneedle to deliver the vaccine into the skin instead of the traditional intramuscular stab in the arm.

Who knew the choices for receiving a flu shot could multiply so quickly in just the past 10 years? First there was the introduction in 2003 of FluMist, an inhaled version of the flu vaccine that does away with shots altogether. Now there’s the microinjection – still a shot, technically speaking, but with considerably less of the ouch factor; it involves an ultrafine needle that’s 90 percent smaller than the usual flu vaccine needle and penetrates no deeper than the top few layers of skin.

Many of us could use a guide to what’s available in the world of flu shots these days, and who’s eligible for what. Here’s a quick rundown, courtesy of the U.S. Centers for Disease Control and Prevention:

Regular flu shot: Suitable for most people; not approved for infants younger than 6 months. The regular vaccine accounts for most of the flu vaccine administered in the United States each year. It is given as an intramuscular injection, usually in the upper arm. The vaccine contains inactivated, or killed, influenza viruses. Side effects can include soreness, redness or swelling where the injection was given, muscle aches and low-grade fever.

Nasal spray flu vaccine: An aerosol form of the vaccine that’s given as a spray into the nose. Because it’s made with a weakened form of the flu virus, it’s recommended only for healthy individuals between the ages of 2 and 49. Anyone older or younger than this or who has a chronic condition or other risk factor should not receive the inhaled version of the influenza vaccine. The most common side effects among children include runny nose, headache, wheezing, vomiting, muscle aches and fever. Typical side effects for adults include runny nose, headache, sore throat and cough.

Intradermal flu shot: Administered with a prefilled microneedle into the top layers of the skin. This version of the influenza vaccine was introduced in the 2011-12 flu season. It was offered on a limited basis last year but has become more widely available this year. Besides being somewhat gentler than the traditional flu shot, it contains 40 percent less antigen, meaning it requires a lower amount of active ingredients to deliver the same flu protection as the traditional vaccine. Otherwise, the intradermal flu shot works in the body the same way as a regular flu shot and protects against the same three strains of flu as other yearly versions of the flu vaccine.

Intradermal flu shots are FDA-approved for adults ages 18 through 64. Side effects include redness, swelling, pain, toughness and itching at the injection site. These side effects seem to be somewhat more common with this form of the flu vaccine than with regular flu shots. Other side effects that have been noted include headache, muscle aches and fatigue.

High-dose flu vaccine: Designed for adults 65 and older. The high-dose vaccine contains four times the amount of antigen as a regular vaccine and is intended to provide greater protection for older adults whose immune systems have waned with age. It’s given as an intramuscular shot, the same as the regular flu vaccine.

High-dose flu vaccine is not recommended for older adults who have had a previous severe reaction to a flu shot. As with the intradermal vaccine, side effects seem to be reported more frequently; they include pain, redness and swelling at the injection site, headache, muscle aches, fever and overall malaise.

Although it’s a welcome development to have more options, it puts more burden on the consumer to make an appropriate choice. Aside from eligibility, one of the key questions is this: Regardless of which form of the flu vaccine you choose, will it be effective?

By now, the nasal spray has accumulated a substantial 10-year track record of safety and reliability, especially among children. Some research suggests it’s less effective in adults, however, and the recommendations for who can receive it remain limited to healthy individuals ages 2 to 49.

Because the intradermal vaccine is newer, there are fewer studies that have examined its effectiveness. But most of the researchers’ conclusions are positive, and one study even found that this form of the flu vaccine worked better in older adults. As intradermal flu shots gain wider use, stay tuned for more information evaluating their safety and effectiveness.

One thing on which there’s a clear consensus among the researchers: Whether it’s a shot in the arm, a spray up the nostrils or an injection into the skin, the flu vaccine only works in those who actually receive it.

3 thoughts on “A (flu) shot in the arm

  1. This year I received a regular flu shot (not skin type) at the back of my arm and not in the shoulder muscle. Talking to a nurse friend she stated that this was not effective and as we had the same doctor (hence same nurse) she was injected in the shoulder muscle. I am 72 and concerned, Can I receive another flu shot for insurance. Thanks.

  2. Pingback: Ah, Science: Redheads, Booze, Booms and Shots | Oh Look, a Shiny Thing!

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