COVID-19 vaccines: what happens after clinical trials

If a COVID-19 vaccine is to reach the global public sometime next year, it will be the result of one of the fastest developments and rollouts of a vaccine against a new disease ever. In contrast, the RTS,S malaria vaccine, which is currently undergoing its first nationwide pilot trials, was first developed over 30 years ago. But once these COVID-19 vaccines have been through clinical trials, what has to happen next before they can be used?

Gavi/Jiro Ose


With hundreds of COVID-19 vaccine candidates in development, there are now 35 in clinical trials across the world, from the UK and South Africa to USA and China. These clinical trials will see the vaccine candidates tested in human volunteers to assess their safety and effectiveness. But even then, after it has been tested on tens of thousands of people, the safety checks are not over. Once a vaccine has proved itself to be both safe and effective in phase 3 clinical trials, it still needs to run a regulatory gauntlet before it can be approved, licensed and deemed fit to be given to people.

Vaccines usually take more than a decade to develop and test, but because of the impact of COVID-19, and the urgent need for a vaccine to end the acute phase of this pandemic, normal regulatory processes are being adapted to move more quickly. Yet no matter how quickly they are accelerated, these procedures must still demonstrate that the vaccines are safe, as well as effective.

Yet no matter how quickly they are accelerated, these procedures must still demonstrate that the vaccines are safe, as well as effective.

Passing the regulator’s standards

Once a vaccine has been successful in clinical trials, the journey from laboratory to routine use is far from over. The vaccine developer must present the scientific evidence from their studies to regulatory authorities if they want the vaccine to be licensed. Every country has its own regulatory authority which assesses all new vaccines to decide if there is enough good evidence that they are safe and effective. Examples are the USA’s Food and Drug Administration, South Africa’s Medicines Control Council, and the UK’s Medicines and Healthcare products Regulatory Agency.

The criteria for what is considered a safe vaccine is higher than for other drugs because vaccines are given to healthy people, rather than ill people for whom some side effects might be acceptable if it means treating or curing a disease.

In the case of COVID 19, WHO is still considering what level of efficacy will be acceptable. But given the size of the pandemic, the urgent need for a vaccine and the sheer number of people who stand to benefit from it, even a COVID-19 vaccine with a relatively low efficacy would still have a massive positive health impact by protecting people, provided it was safe.

All eventual COVID-19 vaccines, however, will have to pass these regulatory checks before they can be delivered to the public:

Regulatory check  1 - Is the science sound?

The authority will usually seek the help of independent scientists who are experts in the field and who can check that the methods and data from clinical trials are thorough and reliable. They will want to see that all the data has been looked at, and not ‘cherry picked’ to paint a positive picture, and that the methods used are ethical and evidence-based.

Regulatory check 2 – Is the manufacturing site safe?

Teams will also visit the vaccine manufacturing site to check it meets the necessary safety standards. To help with this check, more than a hundred national regulatory bodies have adopted a set of guidelines developed by the World Health Organization (WHO), called the Good Manufacturing Practices (GMP). These guidelines lay out what should be expected for a well-run, safe manufacturing process.

Regulatory check 3 – Are the labels correct?

Authorities will have specialists that review the labelling and documentation included with the vaccine that will be read by clinicians and patients. This means it can be administered safely each time. Information for patients will need to be clear and easy to understand so that everyone knows what they are receiving and any side effects to look out for.

Regulatory check 4 – making a recommendation

After taking all these steps, the authority will make a recommendation as to whether the vaccine is safe and effective for the public.

Developers may also submit their vaccines for WHO prequalification. Prequalification means that WHO has worked with the regulators in member organisations to carry out the same steps as outlined above. This is beneficial particularly for people in developing countries whose own regulatory bodies might be underdeveloped, under-funded or lack the necessary expertise.

Regulatory check 5 – ongoing monitoring

Some regulators will want developers to monitor how well the vaccine works long-term. For example, it’s important to know how long the vaccine provides immunity for, and that any side effects that occur later, are noticed and documented. Regulators might demand that the developers provide a plan for ongoing research to track a vaccine’s effects.

The final hurdle – Who’s paying?

Local authorities might also make decisions about whether the vaccine should be funded through government healthcare or not, and they will negotiate with its developers over the price of the vaccine.

How is COVID-19 regulation being fast-tracked?

In the case of COVID-19 vaccines, both the FDA and European Medicines Agency (EMA) are fast tracking the regulatory approval process so that the safety checks can move a lot faster than normal. The EMA, for example, has reduced the review time from the usual 210 days to 150 by using new processes, such as a pool of experts already in place to immediately review submissions.

The aim is to get a vaccine to as many people as possible, as quickly as possible, all while ensuring the vaccine does its job safely.

Some regulatory bodies have other procedures that can be used in public health emergencies, such as COVID-19. The FDA has a protocol called Emergency Use Authorization, which allows treatments that have not been fully approved to be administered to the public if the impact of not doing so would be worse. Similarly, WHO has established the Emergency Use Listing Procedure, a process that can allow medical products that have evidence of effectiveness but are not yet prequalified to be delivered to the public for a limited time.

If a vaccine has been tested, why the regulation?

It might seem strange that more review is needed if a vaccine has already been tested in the laboratory and in clinical trials, but it is an important additional safety check.

Amongst other factors, some criteria regulators might assess include:

  • Is there a wide variation in the clinical trial participants in terms of age, ethnicity and other demographic factors;
  • No evidence of adverse effects in pregnant women who conceived within 30 days of receiving the vaccine;
  • A quality manager, whose role it is to monitor manufacturing processes and ensure standards are maintained, is in place at trial manufacturing sites.

By reviewing the scientific evidence and manufacturing plans against these criteria, the authorities can make sure their population is protected from poor scientific research or vaccines that haven’t been thoroughly tested. The aim is to get a vaccine to as many people as possible, as quickly as possible, all while ensuring the vaccine does its job safely.

Countries in regions team up to share resources

The European Medicines Agency (EMA) is a regional body that undertakes the review of vaccines and other drugs on behalf of European Union member states. The EMA then provides recommendations to its member nations whether to licence or not licence any vaccines it reviews. Approval from the EMA does not mean a vaccine can automatically be used in the member nations. Each country’s regulatory body will still make its own, final decision. 

Other parts of the world are looking into creating similar regional agencies: The African Union has plans to develop an African Medicines Agency which will build on the work of the African Vaccine Regulatory Forum. Signing up to a regional body can benefit individual countries as it reduces the time and financial burden of reviewing lots of different medicines. Vaccine and drug developers also benefit, as they only need to submit information to one regional body, not every individual country.