In a call with clinicians, the US Centers for Disease Control has outlined who should should avoid the Johnson & Johnson COVID-19 vaccine, reports MedPage Today.
The CDC said patients with a prior history of an episode of an immune-mediated syndrome characterised by thrombocytopenia and thrombosis, such as heparin-induced thrombocytopenia should avoid the JJ&J COVID-19 vaccine in the immediate aftermath of their illness, writes Molly Walker, Deputy Managing Editor, MedPage Today. "Because the aetiology of thrombosis and thrombocytopenia syndrome (TTS) appears similar to heparin-induced thrombocytopenia, patients with a similar immune-mediated syndrome should be offered another COVID-19 vaccine for at least 90-180 days after their illness resolves."
Pregnant women can receive the J&J vaccine. While thrombosis risk is higher during pregnancy and postpartum, as well as with hormonal contraception, "experts believe these factors do not make people more susceptible to TTS," CDC staff noted.
While women under age 50 can receive any authorised COVID-19 vaccine, they have an increased risk of TTS associated with the J&J vaccine. CDC staff said they should "be aware of the rare risk of TTS" and in the US may opt for one of the other authorised vaccines, such as the mRNA vaccines from Pfizer and Moderna.
However, there were no such caveats for patients with risk factors for venous thromboembolism (VTE), or a prior history of thromboses not associated with thrombocytopenia. CDC staff said the biologic mechanisms for VTE and arterial thrombi were different from the "underlying immune mechanism" for heparin-induced thrombocytopenia. Therefore, these patients were unlikely to be at increased risk for TTS, they said.
The CDC's Dr Sara Oliver urged people taking aspirin or anticoagulants as part of their routine medications to not stop taking them prior to the J&J vaccine, nor should people start taking these medications prior to receiving any COVID-19 vaccine.
Clinicians asked whether patients with a history of stroke or risk factors for stroke should avoid the vaccine. Oliver said because the phenomenon appears to be immune-mediated, "people who have a history of other embolic events, including stroke, do not appear to be at increased risk for developing" TTS, and there were no recommendations for people with a history of stroke to avoid this vaccine. Similarly, those with other risk factors, such as smoking or obesity, did not appear to be at increased risk of developing these rare blood clots.