Despite skepticism from voters, two of the nine companies pledging to follow “high ethical standards and scientific principles” in submitting vaccine candidates for review – Pfizer and AstraZeneca – show no signs of slowing down.

AstraZeneca has recently resumed final-stage testing of its vaccine candidate after temporarily halting the trial when a clinical trial volunteer was hospitalized with serious side effects.

Pfizer announced it will be expanding its clinical trials to include thousands more patients, with CEO Albert Bourla saying a vaccine could be distributed before then end of the year if it is found to be safe and effective.

Regardless of how quickly a vaccine is approved, distribution will take far longer. The number of available doses to start will be limited due to shortages in supplies and the vaccine will be distributed in a phased approach.

One vaccine manufacturer is warning that production capacity is not increasing rapidly enough to meet demand and 2024 may be the earliest for everyone in the world to be inoculated.

Back in August, Russia was the first country to approve a vaccine for widespread use despite not having completed large-scale trials. Meanwhile China has already vaccinated hundreds of thousands of Chinese citizens – before the state-owned vaccine developer concluded phase three clinical trials.