The first Covid-19 vaccination in the US took place on 14 December 2020. Now, almost a year later, results from an ongoing monitoring system provide reassurance to the public that the vaccines are safe and effective against the deadly disease.
In an ongoing study, a research team has been analysing the medical records of millions of Americans who received an mRNA jab - by Pfizer-BioNTech or Moderna - since the start of the country's vaccine rollout. The purpose of the analysis is to track vaccinees' health before and after their vaccination.
The work is being carried out by federal and private insurance researchers in the US, with funding and support from the Centers for Disease Control and Prevention (CDC).