In the unprecedented race to develop a COVID-19 vaccine, the World Health Organization says that there are no “cutting corners” in testing the safety and efficacy of a new vaccine candidate.

Vaccine development has moved at an unprecedented pace. In six months, some 26 candidates are already undergoing human testing, while 139 more are in preclinical trials, according to WHO’s COVID-19 vaccine tracker. Russia recently announced its intention to approve a Russian vaccine by August 10, although they have not released any safety and efficacy data to the public nor to WHO.

Following the Russian announcement, more concerns have been exprssed that vaccine developers may be making compromises in safety and efficacy studies for speed.

Six other vaccine candidates, not including the Russian vaccine candidate,  are already in Phase III clinical tests, the last stage of mass testing in humans according to WHO’s tracker. This crucial phase of testing helps determine whether the vaccine candidate can truly protect against COVID-19 infection, COVID-19 disease, or severe illness.

But a senior WHO official expressed confidence on Thursday that safety corners are not being cut, despite the speed at which R&D is taking place. Results from preliminary trials of all other six vaccine candidates, not including the Russian one, have been submitted to WHO’s vaccine tracker and are being monitored by the organization.

“This is about accelerating the process of development, putting the risk on the financial side of the equation, not on the safety side of the equation, and ensuring that there’s enough [vaccine] production to meet the needs around the world,” said WHO Health Emergencies Executive Director Mike Ryan at the Apsen Security Conference.

But even after a vaccine is approved and deployed widely, Ryan said, scientists will continue monitoring safety and efficacy signals.

“We will still have to remain cautious as we scale up the number of people vaccinated. Rare side effects…only become apparent when you vaccinate lots and lots of people. So there will still be a need for a monitoring phase, even when we start to vaccinate a population level,” said Ryan.

“There are no cutting corners here,” he warned.

Many Unknowns With Russia’s Vaccine Candidate

Ryan’s comments come a week after Russia announced its intention to approve a vaccine candidate developed by the Moscow-based Gamaleya Institute, by August 10th, and begin mass immunizations by October 2020, according to CNN. Russia has the fourth highest number of coronavirus cases in the world, reporting over 870,000 cumulative cases.

Meanwhile, in a race that has taken on some of the feeling of a Cold War-era rivalry, the United States has said it expects a vaccine only to be approved at the earliest by the end of 2020 or beginning of 2021. The United States’ epidemic has dwarfed other countries’ outbreaks with more than 4.8 million cumulative cases reported.

China, the original epicentre of the world’s outbreak, has already approved a vaccine candidate for military use, although experts remain concerned about the efficacy of the vaccine, and Phase III tests are still ongoing.

“It’s another Sputnik moment,” Kirill Dmitriev, head of Russia’s sovereign wealth fund, the financier behind the Russian vaccine, told CNN. Dmitriev was referring to the Soviet Union’s first ever successful satellite launch, ahead of the United States’ launch in the infamous ‘Space Race’ of the 20th century. “Americans were surprised when they heard Sputnik’s beeping. It’s the same with this vaccine. Russia will have got there first.”

But Russia’s vaccine is not one of the six that WHO has been monitoring in clinical trials. And the Organization has said that so far, they have not received any information on the effectiveness and safety of the vaccine from Russia’s trials. Critics have been concerned that the vaccine has not yet undergone enough testing to verify its safety and effectiveness.

Human Challenge Studies Can Be Justified, But May Not Be Required For Testing COVID-19 Vaccines

Speaking at the Aspen event, Ryan also said that human challenge studies, in which individuals in a vaccine trial are purposely inoculated with the virus to test a vaccine candidate’s efficacy, are not necessarily required in the context of COVID-19.

Normal final phase clinical trials draw their conclusions by enrolling massive numbers of people, under the assumption that enough participants will be naturally exposed to the infectious agent to test the vaccine’s efficacy. The large sample size allows scientists to tease out conclusions that could be missed in smaller trials; but these trials can take more time to carry out.

As a result, some experts, including a Harvard bioethicist, have proposed that carefully designed, smaller human challenge studies may be the fastest way to test a vaccine candidate’s efficacy.

Ryan said that a WHO committee is considering the implications of human challenge studies, examining parameters to conduct them in a safe and ethical manner.

“Obviously, we do not fully understand the long term consequences of natural infection, even in younger adults, and we will have to be very careful for instituting human challenge studies,” he said. “They will have to be very carefully assessed for their ethics and the potential health effects. But there are certainly circumstances in which such trials can be justified.”

However, he added that since COVID-19 has become so widespread, larger-scale trials of the traditional kind can be completed within a relatively short time-frame.

“[Human challenge studies are] usually done when there’s very low level of human disease, and therefore it’s difficult to demonstrate efficacy,” explained Ryan. “In this case we have disease, all over the world so we should be able to demonstrate efficacy of the vaccine in the traditional way by large-scale population based trials.”

Image Credits: Johns Hopkins CSSE.