The first COVID-19 vaccine is unlikely to be effective enough to end the global pandemic, vaccine experts say. Instead, we can live with the virus for years before a winner emerges.
According to US health authorities, who are increasingly confident that some kind of vaccine will be widely available by December, the first large-scale study in humans with two coronavirus vaccine candidates will begin in July.
“I am cautiously optimistic that we will get a vaccine with the numerous candidates we have on different platforms,” Anthony Fauci, chief of the National Institute of Allergy and Infectious Diseases, said Tuesday at a briefing in the Journal of the American Medical Association (JAMA). He predicted that nearly 100 million doses of a successful vaccine would be available by November or December and possibly 200 million doses by early 2021, largely due to fiscal and philanthropic investment in factories being built to produce the huge amount of vaccine.
According to the New York Times, the White House’s Warp Speed operation is expected to name five companies – Moderna, AstraZeneca, Johnson & Johnson, Merck and Pfizer – to lead the vaccination effort in the United States.
Vaccines essentially mimic an infection – without making you sick – and train your immune system to quickly produce antibodies that fight off a real attack. The greatest hope for a vaccine came after a May study showed that almost everyone who recovers from COVID-19 produces antibodies against the corona virus, also known as SARS-CoV-2, which means that the virus can be fought with a vaccine. “That’s a pretty good proof of concept to say that you’ll trigger an immune response in response to a vaccine,” said Fauci.
But what makes a successful vaccine? The first ones to emerge from the 10 candidates currently being tested on humans worldwide are probably similar to the seasonal flu vaccine. These vaccines have to be administered year after year and sometimes only block infection by about 30%. At the same time, they promise milder symptoms for people who get sick. This is in stark contrast to other vaccines, such as the measles vaccine, where two shots give immunity for life.
“When people talk about the race for the COVID-19 vaccine, I have to say, ‘Be careful what you wish for,’ said vaccineologist Peter Hotez of Baylor College of Medicine, “History tells us that the first ones have built-in obsolescence.”
This could be our vaccine future:
There are four types of coronavirus vaccines – some promising and some overblown.
Together with the 10 SARS-CoV-2 vaccines currently being tested in human trials, more than 120 other vaccines are being tested in test tubes and laboratory animals, according to the World Health Organization. Hopefully, everyone wants to produce enough of the right “neutralizing” antibodies to prevent future infections. The trials involve two groups of volunteers who are randomly selected to receive either a real vaccine or a placebo, and then measure the differences in the number of people infected or in severe symptoms.
By and large, the candidates use four methods, only two of which have been shown to be effective in previous vaccines. The first is to give people a weakened or killed form of an actual virus used in polio, chickenpox and influenza vaccines. The second proven way is to inject only a small fragment of the virus to trigger immune preparedness, like the HPV vaccine or newer influenza vaccines.
A third innovative approach is currently being investigated by AstraZeneca and the University of Oxford, whose vaccine is expected to enter a large human trial in July. It takes a chimpanzee virus and coats it with the tiny spines that cover the surface of SARS-CoV-2. The chimpanzee virus causes a harmless infection in humans, but the spike proteins activate the immune system to detect signs of future SARS-CoV-2 invasion.
That’s theoretical. “There is no guarantee that you will receive an effective vaccine,” Fauci said. The US Agency for Advanced Biomedical Research and Development has committed more than $1 billion to the development of the Oxford vaccine and AstraZeneca has announced a plan to test the candidate on more than 10,000 people in the UK.
In early data, however, the vaccine has understated observers who found that it did not prevent infections in monkeys, but only reduced their symptoms. William Haseltine, a former Harvard Medical School professor known for his central research on cancer and HIV, found that the neutralizing antibodies produced by the vaccines were “extremely low” in Forbes.
“Time will tell if this is the best approach,” Haseltine concluded. “I wouldn’t bet on it.”
The fourth approach is a genetic vaccine in which only the genes required by cells to produce the coronavirus spike are injected into a person. These spike proteins, dutifully produced by cells in response to the genes, alert the immune system and should create immunity.
A genetic vaccine that has emerged as a Wall Street favourite is being developed by a company called Moderna. The company is expected to begin large-scale human trials in July as part of Operation Warp Speed. It has upset scientists by issuing only press releases with scarce data on its small-scale human safety experiments and has fed the hype about its vaccine candidate.
The only vaccine that has published strong results – albeit only in monkeys and other laboratory animals – comes from China’s biotech company Sinovac, which relied on the old-fashioned method of injecting a small amount of dead virus to prepare the immune system for a real infection. “This is an old-school vaccine,” said Hotez. “We know this work.”
However, without complete data to measure the effect of the vaccines in humans, outside experts are rather skeptical about their ability to prevent infection. Vaccine experts prefer candidates to be at least 70% effective in preventing infection, said Paul Offit of Philadelphia Children’s Hospital at a separate JAMA briefing on Monday. Even if the vaccine only reduces the severity of a fatal disease, he added that “that would be great because it keeps you away from the hospital and keeps you from dying.
But scientists warn that we should expect delays – especially if the pandemic continues to slow down.
The two candidates for Operation Warp Speed will begin 30,000 human trials in the first week of July, Fauci said. In these trials, most of which will take place in the US but also overseas, some volunteers will receive a vaccination at random and others a placebo. These studies are at the mercy of the size of the outbreak in which they take place because you need enough people in the placebo group to be infected to know that the vaccine is working.
If the trials do not show a high rate of infection, “it can take months and months and months to get a response,” Fauci said. On the other hand, if the trials are in a large increase in cases, “you could get your answer pretty quickly.”
As infections continue but do not increase nationwide, probably because people continue to take physical distancing measures, there is a real concern that the clinical trials could extend over months. In this case, trials usually require more participants to be added, which leads to delays. A rotavirus vaccine study of 40,000 children in 2006 grew to over 70,000 for this reason, Offit said, and lasted more than three years. “It’s hard to study something that doesn’t happen.”
This could easily delay a vaccine after December. Ken Frazier, the CEO of Merck, one of the companies reportedly selected for the Warp Speed trials, told the Financial Times in May that the 12-18 month period required by the program was “very aggressive” and an unrealistic standard for his company.
Whatever vaccines emerge may not make us immune for a lifetime.
Even if researchers have an answer, Offit added that he would be surprised if a SARS CoV-2 vaccine is ever more than 70% effective against infection. This is because of the short incubation period that respiratory diseases such as influenza or COVID-19 even give a prepared immune system to strengthen the defenses and release antibodies. It takes four to five days for people exposed to the corona virus to develop symptoms. In contrast, measles has an incubation period of 10 to 12 days, which helps ensure that the measles vaccine is 97% effective for life after only two doses.
Fauci befürchtet auch, dass Menschen häufig Booster-Impfungen gegen Coronavirus-Impfstoffe benötigen, und stellt fest, dass die Antikörper des Immunsystems nach einer Infektion mit den vier alltäglichen Coronaviren, die etwa 20% der Erkältungen verursachen, tendenziell nachlassen. Hotez war darüber weniger besorgt und argumentierte, dass das Immunsystem durch andere Immunzellen, die jahrzehntelang im Körper Bestand haben können, immer noch ein Gedächtnis für Spike-Proteine behalten sollte. Er räumte jedoch ein, dass es noch untersucht werden muss, da SARS-CoV-2 den Wissenschaftlern erst seit sechs Monaten bekannt ist.