News over the past few days of promising early results from experimental COVID-19 vaccines has, perhaps understandably, triggered a wave of optimism that the world’s worst health crisis in a century may soon be over.
Commenters online cheered the “glimmer of hope,” with at least one professing they were “manifesting” success for the vaccine candidates.
But do the early results really signal that our long global nightmare is at an end?
Well, don’t pop the champagne just yet.
Around the world, as of this week, 27 vaccine candidates were being tested in human trials, and more than 165 in total are in development, with most in pre-clinical studies, according to the New York Times.
Reports emerged on Monday that British-Swedish pharmaceutical giant AstraZeneca’s coronavirus vaccine, developed by researchers at the University of Oxford, was described by the company as inducing a “robust” immune response in all evaluated participants in a Phase I/II trial of 1,077 adults. According to AstraZeneca, “neutralizing activity against SARS-CoV2” was seen in 91 percent of participants one month after vaccination, and in 100 percent of those who received a second dose, all reportedly without serious side effects.
Chinese company CanSino Biologics has similarly revealed that mid-stage results showed strong immune responses and minor side effects, with results published in the medical journal The Lancet alongside AstraZeneca’s.
“This is a time for optimism,” Ruth Karron, director of the Center for Immunization Research and the Johns Hopkins Vaccine Initiative, told VICE News.
“However, we won’t know if these vaccines are truly safe and effective until we have data from the Phase 3 trials.”
In clinical trials, there are several phases. In Phase I, the drug is tested in small batches, and then in larger groups in Phase II. Once preliminary data suggests the drug is effective and safe, it proceeds to Phase III trials, where it’s tested on thousands.
Kawsar Talaat, a Johns Hopkins assistant professor and a researcher on the design and conduct of clinical vaccine trials, underscored the importance of Phase III trials. While there is “reason for optimism” with early-stage successes, she said, it’s not until the Phase III trials—which confirm the safety of a vaccine and demonstrate its efficacy—that it becomes clear if a vaccine can be used among the wider public.
Some vaccine candidates, meanwhile, are already progressing into Phase III—but that doesn’t mean they’ll be ready anytime soon.
Chinese state-owned pharmaceutical company Sinopharm has launched Phase III trials in the United Arab Emirates, while a private Chinese company, Sinovac Biotech, is beginning to recruit volunteers for a Phase III trial this month in Bangladesh and Indonesia. It has also begun construction on a plant, expected to be completed by the end of the year, with the aim of making up to 100 million shots annually, Reuters reports.
Still, the Sinovac trial isn’t expected to be completed until January, with 1,620 samples tested, according to Kusnandi Rusmil, a professor at Padjajaran University Medical School quoted in the Jakarta Post.
Mike Ryan, executive director of WHO's emergencies program, told Reuters on Thursday that while “good progress” is being made, it won’t be until early 2021 until we start seeing people getting vaccinated.
Even so, some countries are already putting in orders. The U.S. government is paying $1.95 billion for 100 million doses of an experimental vaccine—to be provided to Americans for free—developed by Pfizer Inc. and BioNTech SE, according to the Wall Street Journal.
Lawrence Moulton, a Johns Hopkins University biostatistician studying infectious diseases, told VICE News that he expects many of the experimental vaccines in testing to elicit some immune responses, but that does not mean they will be effective against infection.
“It means we have a better idea of which vaccines, and which formulation and dosing schedules, to proceed with for further evaluation. I will not start jumping up and down until I see positive results of Phase III trials,” he said.
Ashley Lauren St. John, a professor and principal investigator at the laboratory of Immunity and Immune Pathology at Duke-NUS, told VICE News that there are hurdles at every stage of the vaccine timeline, but the AstraZeneca and CanSino candidates appeared to have cleared two key ones: tolerability and immunogenicity—a vaccine’s ability to activate an appropriate immune system response.
“Those vaccines don't need to be perfect and provide protection to everyone but if they can reduce the severity of disease, shorten the disease course, or prevent infection in a majority of vaccinated people that would be the major advance,” she said.
This article originally appeared on VICE US.