> It uses a weakened live virus that can (and apparently has, in the case of the J&J vaccine, which is using very similar tech) cause serious adverse systemic reactions.
There is no evidence to prove the vaccine has caused any serious adverse effects so far. If that were the case, it is unlikely the Data Safety and Monitoring Board (DSMB) and U.S. Food and Drug Administration (FDA) would recommend resuming the trial.
> After a thorough evaluation of a serious medical event experienced by one study participant, no clear cause has been identified. There are many possible factors that could have caused the event. Based on the information gathered to date and the input of independent experts, the Company has found no evidence that the vaccine candidate caused the event.
https://www.jnj.com/our-company/johnson-johnson-prepares-to-...