In the 1960s, scientists developed a vaccine to protect against RSV, a virus that causes pneumonia in infants. But it had severe, unintended results: The majority of the vaccinated babies who contracted the respiratory syncytial virus became even sicker, and two toddlers died.
In 2016, doctors vaccinated nearly 1 million children in the Philippines against dengue fever. But studies showed that for more than 100,000 of those children, the vaccine increased their risk of developing a deadly condition called plasma leakage syndrome.
As the number of COVID-19 cases tops 2 million worldwide and shutdowns send the global economy into a tailspin, the hunt for a vaccine grows more urgent. But forging ahead too quickly could compromise safety.
“The scientific method is a very deliberate process that has been honed over time,” said H. Holden Thorp, a chemist and editor in chief of the journal Science. He added that speeding up the process to develop a cure or prevention for a new, poorly understood virus is like fixing a plane in flight before the blueprints are complete.
Of some 70 potential COVID-19 vaccines in development, four are in the first phase of human clinical trials. If one or more of the candidate vaccines sails through testing with no complications and appears safe and effective, researchers could mass produce it within a few months. But few vaccines make it through phase one, and even if they do, the process doesn’t end there. The U.S. Food and Drug Administration requires three phases of human trials, each one testing more subjects than the last. Accounting for the entire process, it likely will take at least 12 to 18 months for a COVID-19 vaccine to be ready for a global campaign, Marian Wentworth, president and CEO of the Massachusetts-based Management Sciences for Health, told The Guardian.
While that may seem like ages for people anxious for life to return to normal, it’s warp speed compared to the normal 10- to 15-year process to launch a vaccine. Experts are trying to balance the safety risks posed by rushing vaccine tests against the consequences of delaying treatment and prevention during the pandemic.
The benefits of thorough testing aren’t hypothetical. Pre-clinical trials of vaccines for SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome)—which are coronaviruses like the one that causes COVID-19—uncovered a problem known as vaccine enhancement. In some cases, coronavirus vaccines make the disease worse for those who contract it instead of protecting them.
Scientists at the Pasteur Institute in Paris are working on a vaccine that piggybacks on a licensed measles vaccine, speeding up the testing, licensing, and production processes. Researchers are also testing hundreds of potential treatments for COVID-19. The investigation of new drugs will require the same testing as that of vaccines, but experiments to repurpose already existing drugs may move more quickly.