Frankfurt: There are over 50 clinical trials worldwide, testing potential vaccines, known as candidates, against COVID-19. None of the vaccine candidates have been approved.
How far have researchers got in the development of a vaccine?
The majority of vaccine candidates for COVID-19 are still in a pre-clinical phase. That means the candidate vaccines are being tested in animal experiments, for example, rather than with human patients.
When those tests are deemed successful, candidate vaccines can move into clinical trial phases. That's when they are tested with humans. There are three clinical trial phases for efficacy and safety before a vaccine can be approved for use by humans. The phases differ from each other, most significantly in their scale:
In Phase I, a vaccine is tested on small patient groups
In Phase II, a vaccine is tested on larger groups of at least 100 patients; researchers can also test their candidate vaccine in specific subgroups, such as people with pre-existing conditions, or patients with particular demographic characteristics, such as a higher age group
In Phase III, a vaccine candidate is tested on at least 1,000 patients
Some companies, such as BioNTech and Pfizer in Europe, and Sinovac in China, have tested their vaccine candidates in several trials in parallel. For example, they have tested the same vaccine but in different age groups, or with different dosages.
If clinical trials are successful, a company can formally apply to regulatory bodies to have their vaccine approved for use by the general public.
Three regulatory authorities are considered to be particularly important in this context: The Food and Drug Administration (FDA) in the US, the European Medicines Agency (EMA), and the Pharmaceuticals and Medical Device Agency in Japan.
What happens after a vaccine has been approved?
When a vaccine is approved, it doesn't mean everybody can get it immediately.
First, the vaccine has to be produced on a mass scale. With COVID-19, manufacturers aim to produce billions of doses by the end of 2021.
Second, logistics experts have to ensure appropriate distribution of the vaccine, and society has to decide who gets the vaccine first.
In the end, though, it will be up to each individual to decide. A survey of more than 13,000 people in 35 countries most affected by COVID-19 showed that the majority of people asked would choose to get vaccinated.
When can we expect a COVID-19 vaccine?
It can take several years to develop an effective and safe vaccine. On average, it takes between 10 and 12 years, but it can take longer. The search for a vaccine against HIV has been going since the early 1980s — and, so far, without success.
In the case of COVID-19, researchers are racing to shorten the time it usually takes because of the ongoing pandemic. Despite the pressure that that brings, vaccine developers, manufacturers and the World Health Organization (WHO) say there will be no compromises on safety.