COVID: Pfizer reports an unexpected side effect of third booster jab

In terms of side effects, there is very little that sets the third jab apart from the first two doses. The most common reactions to expect include headaches, fatigue, pain and redness on the site of injection, and muscle pain.

However, a study done by Pfizer has revealed that some of their participants reported another unexpected side effect after getting jabbed with the drugmaker’s booster vaccine.

Common side effects

The Food and Drug Administration (FDA) recently released the findings from Pfizer’s study that administered their booster vaccine on 306 participants aged between 18 and 55. They observed all the possible side effects that could manifest after administration. Similar to effects felt from earlier doses, 63.7% of participants had fatigue, 48.4% reported headaches, 39.1% had muscle pain, and 29.1% experienced chills. Surprisingly, only 8.7% of participants experienced fever as a result of vaccination.

Unexpected reaction

As part of the trial, they also monitored any adverse events that occurred and according to their findings, 44 people reported unexpected side effects. 16 of those cases were lymphadenopathy—which is the swelling of lymph nodes or glands.

The study specified that all cases occurred within four days of inoculation and it was predominantly found in female participants. Most of them recovered from lymphadenopathy within the subsequent five days. The study states:

These cases predominantly occurred in female participants and were located in axillary nodes (armpits).

While most of the cases were mild, a participant in their early 40s did experience a more severe reaction. They experienced a swollen lymph node in their left armpit two days after their booster jab which lasted for a total of five days and it affected their ability to use that arm. The report noted:

The investigator-judged severity was based on the participant reporting that the lymphadenopathy prevented use of the affected arm.