Covid-19 vaccines manufactured by two pharma companies
are put on hold over certain pressing matters (technology of covid vaccine).
Inovio Pharmaceuticals has been actively working on a DNA-based Covid-19 vaccine to trigger humans’ immune response. This company is already conducting phase-1 trials for this vaccine and is expected to step up into the next phases soon. 1
However, this plan is currently put on hold as the USFDA 
has raised questions over the technology used for delivering this
vaccine. As per the initial reports submitted to the USFDA, the vaccine’s
delivery device uses an electrical pulse to carry out this task. This is
feasible as the electrical pulse opens up the skin pores to ensure
the vaccine’s consistent delivery.
These queries are expected to be answered by October 2020, as claimed by the company. Following this, it expects the FDA to provide information on the vaccine’s status within 30 days to permit the start of the phase- 2 and phase-3 trials.
The FDA has also asked similar questions to the company in
2016 when the company conducting clinical trials for a cancer vaccine.
Pfizer: technology of covid vaccine
Pfizer is yet another company that is leading the race for the Covid-19 vaccines. The vaccine developed by this company is under phase-3 trials, and the results of this trial are expected by October 2020.
With the vaccine’s effectiveness being evinced by this period, the company had planned to proceed with the EUA  from the USFDA.
This plan has, however, been thwarted by a group of 60 scientists and researchers. These scientists believe that a follow-up on the trial participants for at least one to two months must be carried out to identify any potential adverse effects. This must be done after the administration of the second dose of the vaccine.
Although this might delay the production of the vaccine, many scientists claim this as a vital necessity as this will ensure the public’s confidence. You must also note that this will most probably be the first coronavirus vaccine in the US  if this vaccine’s effectiveness is proven.
- The United States Food and Drug Administration
- Emergency Use Authorization
- United States