By now most people are familiar with how the
COVID-19 vaccine is typically administered: a quick jab to the upper arm. But there is a
lesser known place on the body where the
vaccine has also been approved for
injection: the thigh.
اضافة اعلان
While getting the vaccine in the thigh is rare, there are
some groups of people who may want to consider it. If you fall into one of the
categories below and think you would be better off getting the COVID-19 vaccine
in your thigh instead of your arm, it’s best to discuss it first with your
doctor.
Which adults might want to get a shot in the thigh?
• People with a history or risk of lymphedema in both arms.
Lymphedema is a chronic and painful condition that causes
swelling in parts of the body. It can develop in breast cancer patients, for
example, who require surgery to remove lymph nodes from under the arm. Removal
of the lymph nodes disrupts the flow of lymph, the extra fluid from tissues
that would normally drain through the lymphatic system into the bloodstream,
causing the fluid to back up and the breast, torso or arm to swell on the
affected side.
In both the Moderna and Pfizer-BioNTech clinical vaccine
trials, some participants experienced swollen lymph nodes at the armpit or the
neck region two to four days following vaccination, on the same side where the
shot was administered in the arm. This is a normal short-term side effect that
means the body is responding to the vaccine. In the case of Moderna, the median
duration of swelling was one to two days, and it lasted an average of 10 days
in those receiving Pfizer-BioNTech.
For patients with lymphedema or at risk for lymphedema,
however, this side effect could be concerning. If someone has lymphedema in
both arms or if a patient is at risk of lymphedema in both arms, then some
medical institutions are recommending that their patients get the COVID-19
vaccine in the thigh as a precautionary measure. The concern is that the
vaccine could either make the arms swell even more or, for those who are at
risk of lymphedema, create worrisome symptoms where there were none.
The immune response might also be less efficient if the shot
is administered in an arm without lymph nodes or one that has impaired
lymphatic drainage.
“The lymph vessels are responsible for draining fluid out of
all of our tissues, so if your lymphatic drainage isn’t good, your tissues
swell from fluid — and that would also mean you wouldn’t carry a vaccine very
efficiently from tissue to lymph node,” said Marc Jenkins, director of the
Center for Immunology at the University of Minnesota Medical School.
Patients who had lymph nodes removed from one arm may get
the vaccine in the unaffected arm rather than the thigh, said Cheryl Brunelle,
the associate director of the Lymphedema Research Program at Massachusetts
General Hospital in Boston.
• People who have (or had) breast cancer.
Swollen lymph nodes in the armpit can be a sign of breast
cancer. If someone with a history of breast cancer didn’t know that the
Pfizer-BioNTech or Moderna vaccines can produce swollen lymph nodes, it could
be “very scary for her, thinking it may be a recurrence,” Brunelle said.
To alleviate potential concerns, people with a history of
breast cancer can opt to get the vaccine in the thigh if they wish.
• People who need a mammogram within six weeks of their
COVID-19 vaccine.
Coronavirus vaccinations can cause enlarged lymph nodes in
the armpit or near the collarbone that will show up as white blobs on
mammograms and potentially be mistaken as a sign of cancer. The Society of
Breast Imaging recommends trying to schedule your routine screening mammogram
before your first COVID-19 vaccine dose or at least one month after your second
vaccine dose. But an alternative plan would be to get the vaccine in your thigh
instead.
“Injection in thigh would be extremely unlikely to lead to
armpit nodes swelling,” Dr Constance D. Lehman, the chief of breast imaging at
Massachusetts General Hospital, told The New York Times.
If you prefer to get the vaccine in your arm and have
already scheduled your mammogram, you can keep that appointment — as well as
your vaccine appointment — and call your breast imaging center ahead of time to
let them know about the timing of your vaccine.
If you received the COVID vaccine in the arm in the last six
weeks, your radiologist will expect to see lymph node swelling on the same side
that you received the vaccine. This would be a normal finding unless the
swelling continued for more than six weeks or there were other clinical
concerns; in that case they would take more images as needed, Brunelle said.
Why are the vaccines typically injected in the arm?
The COVID-19 vaccines are designed to be injected into
muscle, and the muscles of the upper arm are convenient for shots and thought
to be less painful than some other areas of the body. But a vaccine can be
injected into other muscles, provided they are near some of the hundreds of
lymph nodes that exist in the body. The upper thigh, for example, is located
near multiple lymph nodes and has already been shown to generate an effective
immune response after vaccination.
Lymph nodes are “absolutely critical for generating immune
responses,” said Dr Akiko Iwasaki, a professor of immunobiology at
Yale University.
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