Questions have been asked following the approval of mRNA vaccines by the US Food and Drug Administration (FDA) for emergency use, some of which have not been tested in human clinical trials.

The FDA approved and authorised the vaccines under the Emergency Use Authorisation (EAU) for updated Covid-19 vaccines formulated to target currently circulating variants and provide better protection against the serious consequences of Covid-19.

Developed by Moderna and Pfizer, the vaccines have been updated to include a monovalent component that corresponds to the Omicron variant XBB.1.5.

The Moderna vaccine approval is based on clinical trial while the Pfizer vaccine is based upon evaluation of manufacturing data. The updated mRNA vaccines are each approved for individuals 12 years of age and older and are authorised under emergency use for individuals aged from six months to 11 years.

As part of the actions, the bivalent Moderna and Pfizer-BioNTech Covid-19 vaccines are no longer authorised for use in the US. The updated vaccines have also been approved for use in Canada using the same data.

It is relatively common practice for the FDA to approve vaccines that have been updated without running in-human clinical trials. One example is the flu vaccine, which is updated annually without requiring a clinical trial each time. Last year, the Covid-19 vaccine was updated without the need for in-human trials, however, a number of people have raised some concerns.

One concern people note is the FDA stating the vaccine is approved by the EUA with questions about whether Covid-19 remains an emergency, especially among children. The World Health Organisation (WHO) has said Covid-19 is no longer defined as a Public Health Emergency of International Concern (PHEIC).

Following the approval, the FDA’s Center for Biologics Evaluation and Research director Dr Peter Marks said: “Vaccination remains critical to public health and continued protection against serious consequences of Covid-19, including hospitalisation and death. The public can be assured that these updated vaccines have met the agency’s rigorous scientific standards for safety, effectiveness, and manufacturing quality. We very much encourage those who are eligible to consider getting vaccinated.”

The FDA was approached for further comment by the Clinical Trials Arena but did not respond.