The Johnson & Johnson (Janssen) COVID-19 vaccine was a single-dose viral vector vaccine, differing from mRNA vaccines like Pfizer-BioNTech and Moderna. It used a modified, harmless cold virus to deliver genetic instructions, prompting cells to produce a piece of the coronavirus’s spike protein. This trained the immune system to recognize and fight the actual virus, building protection. Like other vaccines, it could cause side effects.
Common Side Effects After Vaccination
Individuals commonly experienced mild to moderate side effects, indicating the immune system was building protection. Reactions at the injection site included pain, redness, or swelling, usually subsiding within a few days.
Systemic reactions were also reported, such as tiredness, headache, muscle aches, or chills. Some individuals developed a fever or nausea. These general side effects typically began within one to two days and resolved within a few days. Over-the-counter pain relievers could be used for discomfort.
Rare but Serious Health Problems
While most side effects were mild, the Johnson & Johnson vaccine was associated with two specific rare but serious health conditions. One such condition is Thrombosis with Thrombocytopenia Syndrome (TTS), a rare disorder characterized by blood clots occurring in unusual locations, such as the brain or abdomen, combined with low levels of blood platelets. Symptoms of TTS can include a severe or persistent headache, blurred vision, chest pain, shortness of breath, leg swelling, persistent abdominal pain, or tiny red spots on the skin beyond the injection site. These symptoms typically develop within 6 to 15 days after vaccination. The overall reporting rate for TTS after the Johnson & Johnson vaccine was approximately 3.83 cases per million doses administered, with higher rates observed in women aged 30 to 49 years, at about 8 to 10.6 cases per million doses.
Another rare but serious condition linked to the Johnson & Johnson vaccine is Guillain-Barré Syndrome (GBS), a neurological disorder where the body’s immune system mistakenly attacks its own nerve cells. This can lead to muscle weakness, tingling sensations, and in some instances, paralysis. Other symptoms may include difficulty speaking or swallowing, problems with balance or eye movement, or a loss of bladder or bowel control. Most reported cases of GBS began within six weeks following vaccination. While the exact risk varies, approximately 100 to 132 suspected cases were identified among 12.8 to 13.2 million doses administered, suggesting a risk of less than 1 case per million immunized individuals. The highest risk for GBS was observed in men aged 50 or older.
When to Seek Medical Attention
Recognizing specific warning signs after vaccination and seeking prompt medical attention was important. If you experienced a severe or persistent headache, especially if it started a few days after vaccination and did not improve, medical evaluation was recommended. Similarly, blurred vision or any new neurological symptoms like weakness or tingling should prompt immediate care.
Other concerning symptoms included shortness of breath, chest pain, or swelling in a leg. Persistent abdominal pain or the appearance of unusual bruising or tiny red spots on the skin beyond the injection site also warranted urgent medical attention. Additionally, if you developed trouble speaking or swallowing, problems with balance or eye movement, or loss of bladder or bowel control, it was advisable to seek medical help without delay.
Current Recommendations and Availability
Based on a comprehensive review of vaccine effectiveness and safety data, health authorities, including the Centers for Disease Control and Prevention (CDC), expressed a clinical preference for individuals to receive an mRNA COVID-19 vaccine, such as those from Pfizer-BioNTech or Moderna, over the Johnson & Johnson vaccine. This recommendation reflected a risk-benefit analysis, considering the rare but serious risks of Thrombosis with Thrombocytopenia Syndrome (TTS) and Guillain-Barré Syndrome (GBS) associated with the Johnson & Johnson vaccine.
Despite this preference, the Johnson & Johnson vaccine could still be considered in specific circumstances. These included situations where individuals had a contraindication to mRNA vaccines or were unable or unwilling to receive an mRNA vaccine for other reasons. However, the Johnson & Johnson COVID-19 vaccine expired in the U.S. as of May 2023 and is no longer available for use.