Enlarged lymph glands following Covid vaccination

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Mr Mouli Doddi

Consultant in ENT and Head & Neck Surgery

What is lymphadenopathy? 

Lymphadenopathy is the medical term for enlarged lymph nodes (glands) in the body. We have approximately 500—600 lymph nodes scattered throughout the body, with clusters in the neck, armpits, chest, abdomen and groin.  

What is lymph? 

As blood flows through the tissues of the body, it delivers nutrients and collects waste products. During this process of exchange of nutrients and waste products some of the plasma (the liquid part of blood) from the blood leaks into the tissues. This fluid enters the lymphatic vessels becoming lymph. The lymph travels through the lymph vessels, passes via the lymph nodes and ultimately reaches the bloodstream.  

What is the function of lymph nodes? 

The lymph nodes as a filter and monitors the lymph flowing into them. They trap and destroy substances that the body does not need. Cancer cells are also trapped and destroyed in the lymph nodes. They produce immune cells like lymphocytes that help fight infection.  

When are lymph nodes enlarged? 

The common causes for swollen lymph glands are: 

Infections: More lymphocytes are produced when you have an infection and hence lymph nodes tend to swell when you have an infection.  

Cancers: Cancer can appear in the lymph nodes in 2 ways: it can either start there (Lymphoma) or it can spread there from somewhere else (Metastasis). 

Covid vaccination causing enlarged lymph nodes 

The development of lymphadenopathy after COVID vaccination is a sign of the body’s immune system making antibodies in response to the vaccine.   

Emerging research so far revealed that lymphadenopathy occurred in 11.6% of people who had their first dose of Moderna and Pfizer BioNTech covid-19 vaccines and in 16% of those who received their second dose of Moderna and Pfizer BioNTech vaccines. Studies show a lower incidence of lymphadenopathy (1.5%) with Astrazenica vaccine. Researchers believe that the true incidence of lymphadenopathy after all COVID vaccines would be higher as more evidence emerges.  

The lymphadenopathy occurred on an average 12 days after the first dose and 5 days after the 2nd dose. It was seen to last for about 4 weeks is expected to resolve spontaneously.  

As there is a chance that this vaccine induced lymphadenopathy may mask cancer, experts suggest scanning 4 to 6 weeks after the 2nd dose to check that the lymphadenopathy has resolved.  

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