[Update April 26, 2021]
As of April 25, 2021, the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) recommend the use of Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 vaccine resume in the U.S. after a temporary pause (CDC, 2021 April 25). An analysis of adverse events following the use of the J&J/Janssen vaccine suggest an increased risk of thrombosis with thrombocytopenia syndrome (TSS), however they concluded that the benefits outweigh the potential risks. The complication is rare, occurring in approximately 7 per one million vaccinated women between 18 and 49 years old and 0.9 per one million vaccinations among women 50 years and older. As of April 23, 2021, there were 15 reports of women who received the J&J/Janssen vaccine later developed TSS between 6 and 15 days after vaccination. Women younger than 50 years old should be notified of the risk of TSS and that there are other COVID-19 vaccine options available where this risk has not been seen. If you have received the J&J/Janssen COVID-19 vaccine, you should watch for symptoms of blood clots with low platelets such as severe or persistent headache or blurred vision, shortness of breath, chest pain, leg swelling, abdominal pain or easy bruising or tiny blood spots under the skin beyond the injection site. The CDC and FDA will continue to monitor the safety of all COVID-19 vaccines.
[April 16, 2021]
I received a call earlier this week from my sister, alarmed and concerned after hearing the news of serious blood clots associated with the Johnson & Johnson (J&J) COVID-19 vaccine. She is 44 years old and had just received the vaccine 6 days ago. I reassured her that this complication is very rare, however as a precaution, I asked her to monitor closely for side effects such as severe headache, leg pain or swelling, stomachache or shortness of breath and told her to seek medical care right away if any of these symptoms occur. My two sisters, my brother, his wife and my brother-in-law all received the J&J COVID-19 vaccine. I urgently needed to do some research to understand the significance of this adverse event. Here’s what I discovered.
As of April 13, 2021, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) paused the administration of the Johnson & Johnson (J&J) COVID-19 vaccine to investigate the occurrence of serious blood clot complications. The cases are similar to those reported last March with the Oxford-Astrazeneca COVID-19 vaccine, Vaxzevria. Both the J&J and AstraZeneca vaccines utilize viral vector technology, an inactivated, genetically modified common cold virus or adenovirus, that carries the code for the spike glycoprotein of SARS-CoV-2 to incite an immune response to the virus (CDC, 2021).
As of April 7, 2021, of the 25 million people who received Vaxzevria, 62 cases of cerebral venous sinus thrombosis (CVST), a rare clot in the veins of the brain, and 24 cases of splanchnic vein thrombosis in the abdomen were reported in Europe, mostly in women under the age of 60 (European Medicines Agency [EMA], 2021). Unfortunately, 19 of these cases were fatal. The rare blood clots combined with low levels of blood platelets occurred within 2 weeks of vaccination. One hypothesis is that the vaccine may trigger an immune response that can lead to an atypical syndrome similar to heparin-induced-thrombocytopenia (HIT) disorder. This mechanism may be associated with platelet-activating antibodies against platelet factor-4 (PF4) (CDC, 2021), that can cause arterial and venous thrombosis. Health authorities in the United Kingdom (UK) and Europe have confirmed a correlation between the Vaxzevria vaccine and blood clots however, they have not established a causal relationship (Jiminez, 2021). After analyzing the data, the European Medicines Agency (EMA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA) stated the benefits of the Vaxzevria vaccine continue to outweigh the risks for most people (EMA, 2021).
Since receiving Emergency Use Authorization (EUA) in February, 6.8 million doses of the Johnson & Johnson COVID-19 vaccine have been administered in the U.S. Of those vaccinated, seven cases of CVST in combination with thrombocytopenia (low platelet levels less than 150,000) were reported in women between the ages of 18 and 48 with symptoms occurring between 6 to 13 days after vaccination (FDA, 2021). That equates to less than 1 in a million people who developed the complication. Two of the six were also diagnosed with splanchnic and portal vein thrombosis and four developed intraparenchymal brain hemorrhage, one of whom did not survive (CDC, 2021). As a point of comparison, the incidence of cerebral venous thrombosis in the general population is estimated to be between 2 and 5 per million people per year (Ferry & Canhao, 2020). In addition, a retrospective population study conducted by Devasagayam, Wyatt, Leyden & Kleinig (2016) found that the incidence may be even higher, closer to 15.7 per million people per year.
To prioritize patient safety, the CDC and FDA will collect and analyze more data and are taking the necessary steps to protect the public. They advise patients who received the J&J COVID-19 vaccine to seek medical care immediately if they experience any of the following symptoms (CDC, 2021):
- Shortness of breath
- Chest pain
- Swelling or pain in the lower extremities
- Persistent abdominal pain
- Severe and persistent headaches or blurred vision
- New neurological symptoms
- Severe back pain
- Petechiae or small, pinpoint red spots on the skin (not including the injection site)
- New or easy bruising
The CDC (2021) advises all health care providers to closely monitor their patients for these signs and symptoms. If a patient develops a thrombotic event with thrombocytopenia after receiving the J&J COVID-19 vaccine, obtain a platelet count, evaluate with a screening PF4 enzyme-linked immunosorbent (ELISA) assay and consult a hematologist. Blood clots that develop after vaccination should not be treated with heparin (unless HIT testing is negative) as this could exacerbate the problem. Non-heparin anticoagulants and high-dose intravenous immune globulin may be considered. All clinicians should report adverse events to the Vaccine Adverse Event Reporting System at https://vaers.hhs.gov/reportevent.html
and patients who were scheduled to receive the J&J COVID-19 vaccine should seek alternate vaccine availability, either Moderna or Pfizer-BioNTech.
It will take time for the CDC and FDA to evaluate these cases and determine the effect this will have on the distribution of the J&J COVID-19 vaccine. The potential impact on vaccine confidence
and vaccine hesitancy is concerning, and we need to remember that most, if not all medications and treatments have associated risks. The current rate of CVST reported with the J&J COVID-19 vaccine is approximately 1 in a million people, compared to the incidence that is normally seen in the general population (5- 15 people per million). We have lost over a half a million individuals to COVID-19 in the U.S. and almost 3 million worldwide. The question of whether the benefits of the vaccine continue to outweigh the risks must be answered, and if the regulatory agencies analyze the data and come to that conclusion, it will be critical to share the science with the public.