Vaccines must go through a rigorous process of trials in order to be approved for public use, and this usually takes several years. However, the current public health crisis is speeding up the process, and there are many potential vaccines in development.
There are multiple phases vaccines must pass through to reach approval and the many vaccines in development are in various phases. There are five stages for vaccine approval: preclinical, Phase I, Phase II, Phase III, and approval. In preclinical testing, scientists give the vaccine to animals such as mice or monkeys to see if there is an immune response present. In Phase I the vaccine is given to a small number of people to see if the human immune system responds to it. In Phase II the vaccine is given to hundreds of people in different groups. Groups such as children and the elderly are tested to observe the safety and effectiveness of the vaccine. In Phase III thousands of people are given the vaccine and scientists wait to see how many people become infected compared to those that are given a placebo. The FDA states the Covid-19 vaccine would have to protect at least 50% of people in this phase to be considered effective. The last phase is approval, and in this phase regulators in each country review the results of the trials and then decide whether to approve the vaccine. In a pandemic such as this one, a vaccine can receive emergency use approval before being approved formally.
There are currently more than 165 vaccines in development, but not many have made it through multiple trials. More than 135 vaccines are still in preclinical trials. Out of the ones making progress 19 are in Phase I, 12 are in Phase II, 6 are in Phase III, and one is approved for limited use.
There are 28 vaccines that are currently in human trials, and many of them are expected to be ready for approval by early 2021. Although not formally approved, a vaccine in China is sanctioned for a limited time. A Chinese company called Cansino Biologics developed a vaccine that the Chinese military approved for use for a year as a “specially needed drug.” Besides this vaccine, one of the closest to being ready for public use is from a company called Moderna. Moderna partnered with the National Institute of Health (NIH) to develop the vaccine, and after promising results in Phase II, they launched a Phase III trial on July 27th where 30,000 people will be tested across the United States. A few other vaccines are on similar timeframes, with multiple on track to be available by early 2021.