April 14, 2021

pause for cause

Much of the news today continues to be about the Johnson & Johnson (J&J) vaccine and its “pause” by the CDC and FDA. The process of vaccine approval is a long and complicated one. All of the 3 vaccines now being given in the US, have only “Emergency Use Approval”, or EUA, due to the pandemic emergency. That means they are cautious when reports arise of possible complications, especially when there is more than one case with similar effects. Now they need to examine and look at the cases and make a decision regarding continuing the pause, restarting distribution, limiting its use or withdrawing it completely. Not easy decisions and there is still little data.

Today Katelyn Jetelina, an epidemiologist, who has an excellent and informative blog called “Your Local Epidemiologist” explained very clearly what happened at the Advisory Committee on Immunization Practices (ACIP) emergency meeting today. I highly recommend looking at- she explains in a concise and straightforward fashion what happened, reviews the data, and has charts. She, like me, started her blog when she perceived the lack of simple, clear translation from the scientific to the the non-scientific so people could more easily understand and be informed. I just recently found her blog and find it educational and straightforward.

I also learned more while at work today from my excellent and smart infectious disease colleagues. One is that half of the more than 6 million doses of the J&J vaccine were given in the last 2 weeks. That means surely we will see more cases. Another is that we still don’t have enough data about theses cases which is one reason the pause will continue for now. The New England Journal of Medicine just published a report on April 9 about similar low platelet and blood clot conditions from the Astra Zeneca (AZ) vaccine called Immune Thrombotic Thrombocytopenia . (Immune: caused by antibodies; Thrombotic: causes blood clotting; Thrombocytopenia: low platelets).

The two vaccines are similar in that they use adenovirus “vectors” to get the immune system to make antibodies towards the spike protein. The AZ cases were tested for platelet-activating antibodies targeting platelet factor 4 (PF4)–heparin using platelet activation and enzyme-linked immunosorbent assays (ELISA) and found to be positive. That means that heparin which is usually used to treat blood clots can not be used because that antibody reacts to heparin and it will make matters worse for the patient. A different anticoagulant is needed. Because of this knowledge, testing for the PF4-heparin was done on the J&J cases. Those were positive and that knowledge now guides the advice to not treat with heparin.

Complex stuff which again points out the amazing collaboration and sharing of information that has sped up our understanding of these conditions. Still so much is not known and data gathering is ongoing, including did any of the patients have COVID-19 prior to the vaccine.

More to know is that the President was not involved in the decision. It was made by the FDA and CDC and they informed him. Also know that the decision to pause is due to the Emergency Use Authorization which complicates the ethics of these decisions.

Know what to do if you just got the J&J vaccine: First, don’t panic- this is till 1 in a million, most people have reactions to the vaccine the first few days, a nuisance but not dangerous. The symptoms of this dangerous condition pop up 6-13 days later. Check with your doctor if you get a headache or other symptoms. If you are past 3 weeks, breath easy.

The other data available now is that the two mRNA vaccines have not had these clots.

Wash your hands, cover your nose, keep safe six, pause and be grateful for all of the scientists and epidemiologists sharing their knowledge.

And finally, my caveat is that this is my experience and my opinions, which are subject to change as more information is available, and not related to the organization I work for. Thanks for reading.