Most common side effect of booster jab explained
Image: Getty
As more Aussies are rolling up their sleeves for their Covid-19 booster shots, reports are emerging of all kinds of bizarre side effects. But there is one in particular that is proving the most common.
Most who have received both doses already have an idea of some of the side-effects that can occur, including pain at injection site, tiredness, fever, chills and headaches.
However, the more common adverse effect from the third Covid vaccine appear to be swollen lymph nodes. These are the small lumps of tissue that contain white blood cells to help you fight infection by attacking and destroying germs that are carried through the lymph fluid.
There are hundreds of lymph nodes throughout the body including in the neck, armpit, chest, abdomen and groin.
“Swollen lymph nodes are a normal and known side effect of vaccines and occurs when the immune system is stimulated,” the TGA said, adding it was observed during clinical trials for the Covid-19 vaccines.
For Pfizer, it has been found to occur more frequently after a third dose, with about 5% of people reporting experiencing swollen lymph nodes. This is compared to the less than 1% of people who reported this side effect after the first or second doses in the clinical trials.
For Moderna, this side effect occurred in up to 10% of people.
Swelling may be noticed near the injection site within a few days of the vaccination, for example in an armpit where the lymph nodes are located.
What causes the swelling?
The Covid-19 vaccines contain spike proteins that start to build when injected into your body. These proteins are then carrying into the lymph nodes, activating some of the white blood cells. Immunology researcher at the Walter and Eliza Hall Institute (WEHI), Joanna Groom, told the ABC some of the white blood cells that are stimulator are known “effector” cells and pump out antibodies that neutralise the virus and therefore multiplying, possibly leading to inflammation.
It appears that a fourth Covid-19 booster shot could be on the cards for Australians, with the country’s most senior health official dropping a big hint about additional vaccine doses.
Earlier this month, Israel became the first country to begin rolling out a fourth dose of the vaccine. A fourth dose is already recommended for immunocompromised people in Australia.