You’ve probably heard that some COVID-19 patients are being treated with experimental drugs, with researchers reporting qualified success. Most of these treatments are being given to people who are critically ill or healthcare workers on the frontline.

As these antiviral compounds prove their efficacy, they’ll be used more widely, and the severity of symptoms in many cases will be reduced.

The hope also is that the death rate will drop.

This is good news, but it’s not the pathway to liberation from life under siege. For that we need a vaccine. There are already reportedly 41 early-stage candidates being investigated across the globe.

Scientists at the CSIRO’s high-containment facility in Geelong have fast-tracked pre-clinical testing of two potential COVID-19 vaccines. Photo: AAP

The CSIRO made world news this week by fast-tracking pre-clinical testing of two potential vaccines. This means they are testing the drugs on animals, in this case ferrets, because ferrets seem to acquire the coronavirus in much the same way that humans do.

As reported in The New Daily, it would have ordinarily taken the CSIRO one to two years to get their research this far. They did it in eight weeks. Results of those pre-clinical tests might be available as early as June. The next step would be Phase One clinical tests, which means trialling the drugs on a small group of courageous volunteers. To learn what Phase One subjects go through see here.

Last month, US researchers skipped the pre-clinical stage and went straight to Phase One testing on humans, reflecting the urgency of bringing an end to the COVID-19 pandemic.

The company behind this speedy trial, Moderna Therapeutics, hopes to have an early version of their vaccine ready by the northern autumn, which is September. The plan is to make an early version of the vaccine  available to healthcare workers.

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So we’re going to be out of the woods by Christmas?

No, we’re not. For a new vaccine to be made available to the general population (that is, to land on your pharmacy shelf) can take up to 20 years.

The world obviously can’t stay in lockdown for that long, and scientists are already breaking speed records to set us free.

But even if they have the magic elixir already in hand, it will take at least a year to 18 months before we can all start getting jabbed. Because that’s how long it will take to conduct sufficient testing.

But why?

A bitter history lesson tells us why

The drug thalidomide was developed in the 1950s by a West German pharmaceutical company. It was an anticonvulsive drug, but was marketed to pregnant women as a safe sedative and as a treatment for morning sickness.

Testing of the drug thalidomide didn’t include an investigation into how the drug might affect pregnancy and foetal development. Thousands of babies were born with severe abnormalities.

Indeed, it was deemed so safe that it was sold over the counter, no prescription required in many countries. However, the drug caused about 10,000 babies worldwide to be born with severely malformed limbs. The linked wasn’t revealed until 1962.

How could it ever have been determined safe in the first place? Testing was limited, and confidence in the drug as a safe compound leaned heavily on the fact that it was nearly impossible to suffer a lethal overdose. However, the preclinical tests of the drug failed to investigate what would happen to an animal during pregnancy.

The catastrophe led to a change in how drugs were tested.

The Clutter Incident

In 1955, a batch of polio vaccine had not been fully inactivated and still contained live virus. More than 250 fatal cases of polio were attributed to this mistake, along with several deaths, with the faulty batch traced back to a company called Clutter Laboratories. Thus it became known as the Clutter Incident.

The vaccine was recalled as soon as cases of polio was detected. Vaccinations were suspended, but resumed later that same year and polio was eventually all but eradicated.

The US Centers for Disease Control and Prevention describes , “The Cutter Incident as a defining moment in the history of vaccine development and manufacturing, and of government oversight, leading to the creation of a better system of regulating vaccines.”

While the Australian Academy of Science says the incident illustrates “the importance of strict routine testing,” it also notes that “No such events have been reported since.”

The four stages of testing, and the follow-up

As with any clinical drug testing, vaccine development usually begins with pre-clinical tests in the laboratory on animal models. If a vaccine candidate is found to be unsafe in animals, the work is abandoned and the researchers go back to the drawing board.

If it passes the pre-clinical trial, three phases of human testing begins.

• In phase I clinical trials, the vaccine candidate is given to small numbers of healthy adults with the primary goal of assessing safety. There are usually 25 to 50 volunteers employed for this phase.
• Phase II trials involve hundreds of volunteers, usually healthy. This determines whether the vaccine is effective, and what the optimal dose regimen should be.
• Phase III is where the process slows down because of the sheer numbers of people being tested. During Phase III, the vaccine is administered to thousands of people who are potentially susceptible to the targeted disease.

Phase III usually takes a number of years, and seeks to demonstrate that the vaccine works and its safety is rock solid. It’s during this phase that unusual side effects show up. The rate that those side effects occur will determine whether or not the vaccine goes to market.

In the case of COVID-19, Phase II trials will probably involve healthcare workers on the front line. And because there are many thousands of them around the world, and we are relying on them to stay healthy for the sake of our own survival, Phase III will presumably happen a lot quicker than it normally does.

Still, it will take some months of waiting to see if potentially trial-wrecking side effects show up. Only then will a vaccine be approved for widespread community use.

Even then, safety surveillance will continue. As the Australian Academy of Science explains on its website: “The value of ongoing safety testing of licensed vaccines is demonstrated by the successful identification of potential clinical problems.

Another misstep

“The most recent example is the detection of an increased risk of febrile seizures that unexpectedly occurred in young children given a particular influenza vaccine in Australia in 2010.

“When the problem first became apparent, the use of all influenza vaccines in young children was suspended to allow time for authorities to identify the one type of vaccine preparation causing the problem.

“Meanwhile, influenza vaccines shown not to be associated with unacceptable rates of febrile seizures were reintroduced to ensure that protection against influenza remained available for children at high risk of complications from the disease.”