US regulators have strictly limited who can receive Johnson & Johnson’s Covid-19 vaccine due to a rare but serious risk of blood clots. The Food and Drug Administration (FDA) announced that the shot should only be given to adults who cannot receive a different vaccine or who specifically request Johnson & Johnson’s vaccine.
The decision follows a review of data on the risk of life-threatening blood clots occurring within two weeks of vaccination. US authorities have for months recommended that people starting their Covid-19 vaccinations use the Pfizer or Moderna shots instead.
This is the latest restriction to hit Johnson & Johnson’s one-dose vaccine, which has been overshadowed by the more effective two-dose vaccines from Pfizer and Moderna. In December, the US Centers for Disease Control and Prevention (CDC) recommended prioritising the Moderna and Pfizer shots over Johnson & Johnson’s due to safety concerns.
While the blood clots associated with Johnson & Johnson’s vaccine are rare, officials say they are still occurring. Follow-up studies have consistently shown lower effectiveness for Johnson & Johnson’s vaccine compared with the alternatives.
