Less than a year after an unknown coronavirus that has claimed 1.4 million lives began to spread around the world, several very promising Covid-19 vaccines are about to be released.
Health authorities could give the green light for emergency use in a few weeks, marking the fastest vaccine development for a pandemic in history, but many questions remain.
After months without visible progress, things picked up speed in November, when several drug companies made encouraging preliminary announcements about the effectiveness of their vaccines.
The European Medicines Agency (EMA), charged with overseeing the approval of medicines in the European Union, told AFP that it could approve the first Covid-19 vaccines by the end of the year or early 2021. France, Spain and Italy have been outlined distribution plans on that basis.
On the other side of the Atlantic, vaccination campaigns could begin in the United States in mid-December, assuming the United States Food and Drug Administration (FDA) approves an accelerated schedule for implementation.
Also Read: AstraZeneca Covid-19 Vaccine Faces More Questions After Manufacturing Error
Chinese authorities have already started pricking high-risk patients, and two vaccines were validated for use in Russia even before the final phase of clinical trials began.
Researching, testing, approving, manufacturing, and distributing a new vaccine typically takes a decade or more.
The breakneck pace of development, resulting in half a dozen Covid-19 vaccines, witnessed an unprecedented blitzkrieg of public and private research backed by huge sums of money and interim orders for billions of doses.
But all parties involved insist that the corners have not been cut.
The EU regulatory agency, for example, recognized an effort “to speed up” the evaluation process, but insisted it was “ensuring the same high regulatory standards of quality, safety and efficacy” as for any other drug.
But this extraordinary achievement will not mean that a waiting world is immediately vaccinated.
“The initial supply of # Covid19 vaccines will be limited, so priority will be given to #health workers, the elderly and other populations at risk,” the director of the World Health Organization (WHO) recently tweeted, Tedros Adhanom Ghebreyesus.
The world’s poorest countries, he warned, shouldn’t have to wait until the rich who have reserved billions of doses are served.
“The urgency with which vaccines have been developed must be matched by the same urgency to distribute them fairly,” he said, highlighting the risk that the poor and vulnerable will be “trampled in the stampede” to be inoculated.
Also read: When and which Covid-19 vaccines are likely to be available in Asia
Too early to tell. Since November 9, four drug makers have announced that their vaccines work, most of them more than 90 percent of the time.
The first to report on the results of Phase 3 was the collaboration between the United States and Germany between the pharmaceutical giant Pfizer and the German biotech company BioNTech, followed by the American firm Moderna, a British partnership between AstraZeneca and the University of Oxford, and the state-run Gamaleya Research Institute of Russia. Epidemiology and Microbiology.
But the rush to get results in anticipation of a huge global market means that the announcements were made by the companies themselves and have not yet been supported by publications in peer-reviewed journals, which can take months.
All the vaccines disclosed are near the end of so-called Phase 3 clinical trials, the final step in a process that tests safety and efficacy in tens of thousands of volunteers of different ages and ethnicities spread across the world.
Basically, the effectiveness of a vaccine is determined by comparing the number of people who get sick with Covid-19 in one group of vaccinated volunteers compared to another group that receives a placebo instead of the active drug.
The threshold for publishing the findings, the number of people infected with Covid-19, was different in each case: 170 for Pfizer / BioNTech, 95 for Moderna, 131 for AstraZeneca / Oxford, and only 39 for the Gamaleya Institute.
Pfizer reported an efficacy of 95 percent, with only eight of 170 Covid-19 patients coming from the vaccinated group. For Moderna, with an efficacy of 94.5%, it was nearly identical, while Gamaleya’s Sputnik V vaccine reported an efficacy of 91.4%.
The calculations for the two-dose AstraZeneca vaccine were more complicated. In two variants of the trials with slightly different protocols, the drug worked 70 percent of the time.
Also Read: AstraZeneca Manufacturing Error Clouds Vaccine Study Results
But in a group whose first prick was a half dose rather than a full one, the efficacy rate rose to 90 percent. The counterintuitive result, less vaccine conferring more protection, was likely due to different immune system responses, experts said.
Oxford revealed Wednesday that the 90 percent effective dose was a fluke.
During an initial phase of the trials, some volunteers initially received half a dose in error, which Oxford attributed to a change “in the manufacturing process.”
When the error was discovered, the drug manufacturer, in consultation with regulators, decided to administer the accidental procedure (half a dose followed four weeks later by a full dose) to 3,000 of the subjects as part of the larger Phase 3 trials. .
For all vaccines, the success rate is not the only criterion for determining which vaccine to adopt in different circumstances. Cost and logistics are also factors.
AstraZeneca’s double jab, for example, is by far the least expensive, at around 2.5 euros ($ 3) per dose.
It also has a significant advantage when it comes to transportation and storage. Moderna’s vaccine must be kept at -20 degrees Celsius, while Pfizer’s requires an even cooler -70 ° C temperature to remain viable. AstraZeneca vaccine, on the other hand, can be stored at normal refrigerator temperature.
There are many, including some great ones.
“We knew that a vaccine would be essential to control the pandemic,” Tedros noted. “But it is important to emphasize that a vaccine will complement the other tools we have, not replace them.”
That said, the WHO chief added, “the light at the end of this long, dark tunnel is getting brighter.”
The biggest question mark hanging over all of these vaccines is how long the immunity lasts. All results were reported only a few weeks after administration of the vaccines.
“How long will the protection last? Will the vaccine result in virus ‘escape’ mutations that limit the effectiveness of the vaccine over time?” Penny Ward, visiting professor of pharmaceutical medicine at King’s College, told reporters. London.
A handful of reinfections, in which people recovered from Covid-19 only to become infected with a slightly different strain, also raise questions about the duration of immunity.
Scientists also don’t know yet whether vaccines will be as effective in high-risk people, especially the elderly, who are much more susceptible to life-threatening symptoms.
Another “known unknown” is whether an effective vaccine simply eliminates symptoms or also prevents someone from transmitting the virus to others.
In other words, even if it protects you from getting sick, will it protect other people you come in contact with from contracting the virus?
Here again, AstraZeneca may have an edge over the competition.
“The Oxford / AstraZeneca team has been collecting weekly nasal and throat swabs from all trial participants to look for asymptomatic infections,” Eleanor Riley, professor of immunology and infectious diseases at the University of Edinburgh, told the Science Media Center in London.
The drug maker found “early signs” that the vaccine could reduce transmission of the virus.
When contacted by AFP, AstraZeneca noted that not all 23,000 people in its trial were evaluated for asymptomatic cases, but it did not say how many there were.
The World Health Organization (WHO) has identified 48 “candidate vaccines” at the stage of human clinical trials in mid-November, but only 11 at the most advanced stage of Phase 3.
In addition to the four that announced results this month, there are several Chinese vaccines from state laboratories, made by Sinovac, Sinopharm and CanSino.
WHO has identified 164 other vaccine projects that are still in the preclinical phase of development.
Some methods of making a vaccine are proven, while others remain experimental.
Traditional inactivated vaccines use a virus germ that has been killed, while others use a weakened or “attenuated” strain.
These vaccines work when the body treats the inactivated pathogen as if it were a real threat, producing antibodies to kill it without endangering the patient with a total infection.
So-called “subunit” vaccines contain a fragment of the virus or bacteria from which they are derived to produce a similar immune response.
Strains of “viral vectors” carry fragments of viral DNA into cells, often causing a liftoff of other virus molecules.
For example, a measles virus modified with a coronavirus protein, the apparatus that SARS-CoV-2 uses to attach itself to human cells, can be deployed to provide immunity to Covid-19.
Both Pfizer’s and Moderna’s vaccines are based on cutting-edge technology that uses synthetic versions of molecules called messenger RNA to hack human cells and effectively convert them in vaccine manufacturing factories.
Whichever vaccine is distributed first, there is a final question that scientists cannot answer but that could determine the success of their efforts: In an era of deep mistrust of authority, how many people will refuse to be vaccinated?
According to a study published last month in the Royal Society’s Open Science journal, a significant percentage of people in many countries subscribe to conspiracy theories about the origin of vaccines or the virus itself.
In Mexico, for example, more than a fifth of those surveyed said they thought the pandemic itself was “part of a plan to impose vaccines around the world.”
A survey released earlier this month by the World Economic Forum covering 15 countries found that the number of people willing to get vaccinated had dropped from 77 percent to 73 percent since August.
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