CDC advisers “prefer” mRNA vaccines over J&J

Guidelines likely to be updated to recommend Pfizer or Moderna shots as the first line against Covid-19

After considering data on both overall efficacy and adverse events, the CDC’s Advisory Committee on Immunization Practices Thursday voted to recommend that the CDC officially recommend the Pfizer or Moderna mRNA COVID-19 vaccines over the Johnson & Johnson vaccine, which uses a different technology. However, the advisors agreed that the J&J shots are still safe and effective for the vast majority of people treated and that the overall benefits outweigh the risks.

During the meeting, CDC experts reviewed all available data on the J&J vaccine. There have been 54 cases of an unusual form of blood clots associated with the J&J vaccine, out of more than 14 million doses given. Of those, most recovered, but nine died. Most of the deaths occurred before the pause, during which time the CDC published guidelines for clinicians on how to identify and treat these rare blood clots. Nonetheless, the number is higher than previously thought - the result of CDC and other government experts going back to review possible adverse events another time.

Even though the blood clots are still very rare, experts were concerned that they can be difficult to identify and treat. Adverse events with the mRNA vaccines, such as heart inflammation in young men, have been less serious and more easily treated.

In addition to concern over the rare blood clots, advisors said the reduced efficacy of the J&J shots compared with the mRNA vaccines make the preference for the Pfizer or Moderna shots a logical step. They noted that two doses of the J&J shot have efficacy similar to the mRNA vaccines. A representative for J&J told the committee that it stood behind its one-shot regimen and that the simplicity of a single shot was an important public health advantage.