American and European vaccine manufacturers predict they will have a SARS-CoV-2 vaccine by autumn or early winter, and Russia expects an approval even earlier – in August – with vaccinations starting in September. Even if a vaccine isn’t available until 2021, a vaccine for the COVID-19 pandemic will have been produced faster than any vaccine in history.
The world hopes they’re right, but many are skeptical. The vaccine industry doesn’t have a history of fast vaccine production, even against the relatively recent infections of Zika, HIV and Ebola.
The Zika virus, for instance, was discovered in 1947 in Africa, spread to southern Asia and in 2015 to South America. In 2016, locally-transmitted cases appeared in the U.S. The Centers for Disease Control and Prevention (CDC) reports it can be transmitted by mosquitoes and also sexually.
One of the greatest challenges for immunologists was simply launching Phase III trials, according to researchers writing in BMC Medicine. They cited “the spatio-temporal heterogeneity of Zika transmission, the unpredictability of Zika epidemics, the broad spectrum of clinical manifestations making a single definite endpoint difficult, a lack of sensitive and specific diagnostic assays and the need for inclusion of vulnerable target populations.”
The World Health Organization (WHO) reported 40 vaccines in development in 2017. This month, ClinicalTrials.gov reported 10 trials involving Zika that were active, enrolling, or preparing to enroll patients. Despite promising results from some notable vaccine developers and researchers, as yet, there is no approved vaccine for Zika virus.
HIV was acknowledged as the cause of AIDS in 1984. That year, Margaret Heckler, secretary of the U.S. Department of Health & Human Services (HHS), announced that an AIDS vaccine would be ready for testing within two years. It took three but, 36 years later, people are still waiting for an effective vaccine.
The delay isn’t for lack of trying. The National Institutes of Health advanced the first vaccine candidate entered clinical trials in 1987. By 1998, VaxGen launched the first large-scale trial, enrolling more than 5,400 volunteers in the U.S. and Europe. By 2004 it was clear the vaccine candidate failed to provide protection. Research simmered until 2009, when a 16,000 person Thai trial became the first and, to date, only large trial to show efficacy against AIDS. At 31% efficacy, however, the vaccine wasn’t robust enough to develop.
The problem, Anthony Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases (NIAID), explained in June in the American Journal of Managed Care®, is that “the body does not make an adequate immune response against HIV, which is the reason why no one has yet spontaneously cleared the virus by their immune system.” There are, however, therapies that can reduce the viral load and make the disease manageable.
Ebola outbreaks in 2014-16 catalyzed the need for a vaccine that had proof of concept in 2003. When the Canadian lab offered it to the WHO in 2014, no clinical trials had been conducted. Initially, the WHO declined. As the crisis grew, the repercussions of not offering a potential vaccine outweighed the risks of offering one that was untested in humans, so the WHO began clinical trials in Africa. From only a handful of competitors, Merck became the frontrunner. In November 2019, Merck became the first to gain European Medicines Agency approval for an Ebola vaccine. FDA approval came in December. The WHO declared the 10th outbreak in the Congo to be over in June.
Ebola, HIV and Zika viruses became global challenges that caused researchers and vaccine developers to jump into action but, ultimately, vaccine development takes time. That’s why claims that SARS-CoV-2 vaccines will be available soon often are met with skepticism.
As Matthias Schnell, Ph.D., director of the Jefferson Vaccine Center at Thomas Jefferson University, told BioSpace, one of the issues “is what you consider a vaccine.” When companies say they will have a vaccine ready, does “ready” mean ready for regulatory review, ready for initial dosing, or ready for widespread commercialization throughout a country or the world? The answer is rarely clear.
A commercial product therefore may not be available this autumn, he cautioned. “There may be preliminary data, but an approved vaccine produced in the amount needed for wide-scale vaccinations is ambitious. There always are a lot of claims, but at Phase I, II, and III, things can go wrong.” Consequently, “I have doubts.”
Beyond the scientific challenge of developing an efficacious vaccine, Dr. Schnell said, “Companies will be bringing out a vaccine with no long-lasting data.” As of yet, there’s no widely accepted evidence indicating that immunity is possible against COVID-19 and if there is, how long any of the 165 vaccines now in development and the 27 in human trials may confer that immunity.
“Then they have to produce it in large quantities, store it, and distribute it. That’s not easy logistically. We struggle to do that with the flu vaccine,” Dr. Schnell continued.
For example, during the 2019/2020 flu season, the CDC estimates up to 169 million doses of the flu vaccine were administered. Typically, immunologists say about 60% of a population must be immunized or infected to confer herd immunity. Figures published in Science in June say those figures may be as low as 43%, based on activity level. With an estimated global population of 7.8 billion people, that’s a minimum of 3.35 billion doses that need to be made and distributed as quickly as possible. Even though new manufacturing facilities are being built, capacity is likely to be insufficient for some time.
The difference between COVID-19 and previous viral outbreaks is that the world is throwing everything it has at the virus to find something to prevent infections. Multiple mechanisms of action and delivery systems are being explored, new manufacturing methods are being used, and regulators around the world are cutting as much red tape as possible to streamline development without lessening safety. As a result, some of the claims that vaccinations for COVID-19 will start this autumn are probably accurate. Widespread availability, however, still will take time.
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July 28, 2020 at 01:19AM
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Can a Coronavirus Vaccine Really be Ready This Year? - BioSpace
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