Reacting to reports of potentially dangerous blood clots, the US is recommending a “pause” in immunisations with the single-dose Johnson & Johnson COVID vaccine in order to perform investigations.
The Centers for Disease Control and Prevention and the Food and Drug Administration said in a joint statement that they were investigating blood clots in six women that occurred 6 to 13 days after vaccination. The clots, seen in the sinuses of the brain, also had lowered platelet counts. This renders the use of heparin, the standard treatment for blood clots, potentially dangerous.
Out of 183.5 million vaccine doses administered in the US, over 6.8 million doses are the J&J vaccine — the overwhelming majority without serious side effects. The rest is made up by the two other authorised vaccines, from Moderna and Pfizer.
Use of the J&J shot will be paused in US federal distribution channels, including mass vaccination sites, with states and other providers being expected to follow.
CDC’s Advisory Committee on Immunization Practices will meet Wednesday to discuss the cases and the FDA has also launched an investigation into the cause of the clots and low platelet counts.
“Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution,” Dr Anne Schuchat, principal deputy director of the CDC, and Dr Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a joint statement.
They recommend that people who received the J&J vaccine and are experiencing severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after receiving the jab contact their health care provider.
Officials say that they want to bring healthcare providers up to speed on the blood clot’s “unique treatment” .
Meanwhile, Johnson & Johnson had said it was aware of the blood clot reports, but no association with its vaccine had been established.
“We are aware that thromboembolic events including those with thrombocytopenia have been reported with Covid-19 vaccines,” the company said in a statement. “At present, no clear causal relationship has been established between these rare events and the Janssen Covid-19 vaccine.”
In late February, the FDA granted emergency use authorisation to the J&J vaccine, with hopes that its single-dose and relatively simple storage requirements would speed vaccinations across the country. However, only a fraction of the vaccines administered in the US are the J&J shot. The company has been beset by production delays and manufacturing errors at a contractor’s plant.
The pharmaceutical company took over the facility to ramp up production to make good on its promise to the US government of 100 million doses by the end of May. Only about 9 million of the company’s doses have been delivered to states and are awaiting administration, according to CDC data.
Previously, concern over the blood clots was confined to AstraZeneca’s vaccine, with European regulators saying last week they found a possible link between the shots and an exceedingly rare type of blood clot presenting with low platelets, a situation found more commonly in young people.
Nevertheless, the European Medicines Agency emphasised that the benefits for the vaccine outweigh the risks. Despite this, several countries imposed restrictions on vaccine eligibility and some such as Britain and Greece recommending that people under a certain age be offered alternatives.
Unlike the Pfizer/BioNTech and Moderna vaccines which use mRNA to train the immune system to recognise the SARS-CoV-2 spike protein, the J&J and AstraZeneca vaccines use an adapted adenovirus to introduce the spike protein antigen into the body. Adenoviruses were first identified in the 1950s as a family of similar disease-causing viruses. AstraZeneca’s vaccine uses a chimpanzee adenovirus while the J&J uses a human one.
Source: Medical Xpress
