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Paris (AFP)
Reports that one of the vaccines for Covid-19 has shown very promising results are a ray of hope for a world in the shadow of rising virus cases.
But does it mean that the pandemic is coming to an end? Not so fast, experts say, with many questions hanging over who it will protect and for how long.
On Monday, US pharmaceutical giant Pfizer and its German partner BioNTech said their vaccine candidate has been 90 percent effective in preventing Covid-19 infections in ongoing phase 3 trials.
One of dozens in development, it is based on innovative technology that has never been approved for use before.
While its apparent effectiveness sparked intense excitement, with only partial data released so far, we still don’t know how long it will last, whether it will protect the most vulnerable, and how it could be distributed around the world.
– 90 percent –
Pfizer and BioNTech base their announcement on the interim results of the last step of their clinical trial before submitting an application for approval.
They said the vaccine was found to be “more than 90 percent effective” in preventing participants from becoming infected.
This was based on 94 Covid-19 cases found at this stage of the trial, which has enrolled 43,538 people.
But the ad doesn’t break down those numbers to show how many infected patients were in the group that received the vaccine and how many were in the group that received a placebo.
This points to the deeper problem that the results were distributed in a press release, prompting a surge in the stock markets, rather than a detailed peer-reviewed article in a scientific journal.
“These results are extremely interesting,” said French virologist Marie-Paule Kieny, who leads the research at Inserm and is a former director of the World Health Organization.
“But we have to wait to see the data, which is not yet available,” he told AFP.
Other data is still being collected, particularly on security, although the firms said “no serious security concerns have been raised.”
– Long-term protection? –
Another question is how long the protection of the vaccine can last.
Efficacy was measured seven days after patients received the final injection of the two-dose vaccine, 28 days after the initial injection.
This means we cannot yet know the duration of protection, Penny Ward, visiting professor of pharmaceutical medicine at King’s College London, told the Science Media Center.
“Longer periods of follow-up are required during an ongoing outbreak to determine the need for repeat booster doses.”
With a view to a possible authorization by the United States Drug Administration (FDA), the two companies have indicated that they will also publish the measured results 14 days after the second injection.
Bruno Pitard, from France’s CNRS national scientific research center, told AFP that one of the challenges is knowing how the effectiveness of the vaccine changes over time.
“After three weeks, then a month, then two, then three, then four, we’ll see if the protection remains the same,” he said.
– What does? –
Does this vaccine prevent people from getting Covid-19 or just reduce the severity of their symptoms? And can it stop someone from spreading the virus?
There is no published data that indicates us in any way.
This is a crucial point, Ward said, because if a vaccine can protect against infections, we could theoretically ease the restrictive measures in place to stop the spread of the virus.
However, if it primarily reduces the risk of disease but not infection, then restrictions would be needed “until enough people have been vaccinated to protect those most at risk of needing hospital care or dying from a disease. disease of becoming seriously ill by contracting the infection from a vaccinated person, infected asymptomatically. “
– Who are you protecting? –
After ten months, we have a better idea of who is most at risk.
Older people, men, and those with obesity, diabetes, or high blood pressure are among those most likely to develop serious illnesses.
But Pfizer and BioNTech do not disclose whether their vaccine is effective for these vulnerable groups.
“In scientific publications, we see stratification of individuals, according to their age, the presence of comorbidities (underlying medical conditions), ethnic origin, etc.,” Pitard said.
“We don’t have any of that here.”
– Who can have it? –
The vaccine developed by Pfizer and BioNTech, along with another vaccine from the American firm Moderna, involves injecting strands of genetic instructions called “messenger RNA” into the body, which tell our cells how to fight the coronavirus.
A major disadvantage of these new messenger RNA vaccines is that they must be stored at very low temperatures, in this case -70 degrees Celsius, although they can be kept in the refrigerator for up to five days.
Very low storage temperatures could pose a particular problem for poorer nations in the Global South, said Toby Peters, a professor of cold economics at the University of Birmingham.
“Nowhere on the planet is there the logistical capacity to distribute vaccines at this temperature and volume without massive investment,” he said, adding that “we cannot allow this to become, by default, a split solution” among those who have and those that don’t.
© 2020 AFP
