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SINGAPORE: With COVID-19 cases still increasing globally, the race for a vaccine is on. Pressures build to have one available for use asap.
The pandemic has paralyzed the world, so it’s tempting to think that the faster a vaccine is available, the better.
But it’s important to make sure the vaccines are safe and that they really work.
Vaccine indecision is widespread and the risk of increasing vaccine indecision by launching a vaccine without proper testing is not a risk worth taking.
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The worrying side effects of the launch of the Dengvaxia dengue vaccine in the Philippines should be taken seriously as a conscientious example when it comes to the testing and use of COVID-19 vaccines.
Many diseases can be prevented with vaccines and the path to getting a vaccine developed and available for use is well traveled and clear.
LIFE CYCLE OF TESTS
First, there is a preclinical phase, followed by three clinical vaccine testing phases.
Phases one and two test immunogenicity and safety, and phase three tests efficacy and safety in a larger number of people.
In phase three trials, there is a vaccinated and unvaccinated control group.
These trials aim to determine if infection rates are lower in the vaccinated group compared to the unvaccinated.
Typically, these trials take 3 to 5 years to complete with a candidate vaccine that is already developed.
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But with COVID-19, we’ve seen the development through phase one and two in a matter of months, and vaccines are rapidly moving into phase three.
So it is perhaps easy to think that the next phase can happen just as quickly. But the length of follow-up in phase three trials is vital and cannot be sped up in the same way.
The end of phase two reveals whether a vaccine produces an immune response.
But just because an immune response occurs does not mean that a vaccine will protect against infection or disease.
Examples in Russia and China highlight the potential for widespread use of a vaccine prior to phase three trials.
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The results of phase one for the vaccine developed in China and the results of phase one and two for the vaccine developed in Russia have been published.
But none have started phase three trials, although there are now reports of plans for phase three trials in the Philippines and mixed reports from Brazil on the possibility of phase three trials there.
DANGERS OF SHORTCUTS
The widespread use of vaccines before phase three trials is problematic for two reasons.
First, without the larger group testing in phase three, there may be safety issues that have yet to be determined.
A man works at the packaging facility of Chinese vaccine manufacturer Sinovac Biotech, developing an experimental vaccine against the coronavirus disease (COVID-19), during a government-organized media tour in Beijing, China on September 24, 2020. REUTERS / Thomas Peter / File Photo
Individuals in phase three trials are closely monitored and there is no guarantee that this will happen outside of the trial setting.
A recent example of this process is the discontinuation and restart of the AstraZeneca vaccine trial in the UK after a participant had a suspected adverse reaction.
Second, it is impossible to know if a vaccine works without the control group from a phase three trial.
But even with a good phase three trial, efficacy can only be determined if exposures to infections occur.
Vietnam has been reported to have purchased a large quantity of the Russian vaccine, hopefully to be used in a well-designed phase three trial, however, with low transmission here, it may not be possible to determine the efficacy of the vaccine.
It is also important to consider who is included in all phases of the trials. In the Chinese example, members of the military, a homogeneous group in terms of age and sex, are reported to have been vaccinated.
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This configuration means that vital information about how the vaccine works in certain groups will be missing.
Another reason for collecting excellent efficacy data is the need to compare and choose between multiple vaccines.
WHO GETS IT FIRST?
This is not to say that we cannot speed up other areas of the process. Once a vaccine has been successful in phase three trials, it must be manufactured and made available to the people who need it.
The Russian vaccine was still in the testing phase after its accelerated approval in the country AFP / Natalia KOLESNIKOVA
Building factories to make vaccines at scale before phase three trials are completed will speed up the process, as will building frameworks to make decisions about who will get vaccinated first and how to get vaccines to these groups efficiently. .
All countries are currently debating the future of COVID-19 vaccination for their country.
Many countries have committed to COVAX, the WHO initiative to ensure equitable global access to vaccines when available.
There are many decisions to make for each country, and well-designed trials for all vaccines will mean that each country can make the decisions necessary to improve the health and well-being of its population, with the best possible information available.
Hannah Clapham is an assistant professor at the Saw Swee Hock School of Public Health at the National University of Singapore. This comment first appeared on the East Asia Forum. Read it here.
