The Janssen/Johnson & Johnson COVID-19 Vaccine
The incredible shared focus on developing safe, effective vaccines to combat the COVID-19 pandemic is nothing short of exceptional. To have not just one, but several strong candidate vaccines is perhaps the most significant medical achievement of all time. Yet we know a myriad of concerns surround the rapid release of these vaccines with regards to safety, length of protection, and others.
Last month, reports of blood clots were examined regarding the Astra Zeneca (AZ) COVID-19 vaccine in Europe. Its distribution focused mainly in the UK and Europe; the AZ vaccine did not present a statistically significant finding of blood clots in clinical trials. Ultimately, the European Medicine Agency (the EU FDA) determined the vaccine benefits outweighed the risks. However, European countries are making their own decisions on whether to continue administration of the AZ vaccine, pause, or limit to persons at lower risk for developing blood clots (those over 50).
The mechanism used in the AZ and Janssen vaccines is similar. Both use an adenovirus vector to carry the COVID-19 viral material into the body. The Moderna and Pfizer vaccines do not use a vector but present virus particles directly to the body.
Preliminary research points to the possibility of an autoimmune disorder triggered by AZ or Janssen vaccine administration that results in a blood clot. A similar reaction occurs in 0.2-3% of patients administered a medication used to treat blood clots. This reaction appears more likely in women and those under the age of 50.
Cases related to the AZ vaccine are slightly different in that men were affected as well as women.
We need to keep in mind the first step in epidemiologic evaluation is to review case studies. Cases are examined for similarities, timing between exposures and disease (i.e., vaccination and blood clot), and the possibility of cause and effect. We do not yet know what other factors these cases have in common leading to the outcome.
The next step is evaluating cohorts of people who received vaccine and did not for the occurrence of blood clots. Clinical trial data are re-reviewed. Ultimately, our pharmaceutical governing bodies must determine whether the risk of harm from the vaccine outweighs the benefit of mass immunologic protection.
Statistically speaking, blood clot events among Janssen vaccine recipients are extremely rare at only seven cases among seven million doses administered. That equates to only one per million doses. The Moderna and Pfizer vaccines share an average incidence of three cases of anaphylaxis or severe allergic reaction per million doses.
To put this in perspective, the chance of having a severe allergic reaction to penicillin is 100 out of every 10,000 doses, or a 10% risk, compared to a 0.0001% risk of blood clot with the Janssen vaccine or a 0.0003% risk of anaphylaxis with either the Moderna or Pfizer vaccines.
We are on the precipice of the recovery phase of this pandemic. The entirety of our progress is jeopardized by new variants. The more people infected, the more chances the virus has to mutate.
The question now is whether a one in a million risk outweighs the critical need to mass protect. The single dose vaccine is finally being prioritized for vulnerable, hard-to-reach populations such as homeless or homebound. Removing this tool could dampen the progress to reaching a level of immunity needed to stop widespread infection.
CDC and FDA governing bodies are taking necessary time to review data and determine whether to change the Janssen administration recommendation. The Advisory Committee on Immunization Practices (ACIP) recommended Friday 4/23 to resume vaccination excluding persons with a history of developing blood clots.
References
Joint Media Call: FDA & CDC to Discuss Janssen COVID-19 Vaccine - 4/13/2021 - YouTube
Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination | NEJM
Thrombotic Thrombocytopenia after Ad26.COV2.S Vaccination | NEJM
Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination | NEJM
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Pause of Johnson & Johnson coronavirus vaccine likely to be lifted by Friday, Fauci says
AstraZeneca: PR-Desaster statt Erfolgsgeschichte - news.ORF.at