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The pioneers in the COVID-19 vaccine race have come up with varying success rates of their injections in clinical trials, but what does that mean for the global fight against the pandemic?
US pharmaceutical companies Pfizer-BioNtech and Moderna have said that their coronavirus vaccines have an efficacy rate of about 95% and a Russian project touted 92% efficacy for their Sputnik V vaccine.
Britain AstraZeneca announced an average efficacy rate of 70%, still well above the 50% rate that US regulators have said they want to see before approving a COVID-19 vaccine for use.
WHAT ARE EFFICIENCY NUMBERS?
If a vaccine has an efficacy of, say, 80%, it means that if 100 people who have not previously been infected with the coronavirus receive the vaccine, on average 80 of them will not contract the disease that the virus causes: COVID-19. Rates are related to vaccines administered and monitored in controlled circumstances, such as clinical trials.
DOES THAT MEAN THAT AN INDIVIDUAL’S LEVEL OF PROTECTION IS THE SAME?
No. A person immunized with a vaccine that is, say, 80% effective, is very likely to be protected against disease with symptoms, especially severe ones.
They are also very likely protected from asymptomatic diseases, but this, depending on the vaccine, may be less safe.
Even at 95% efficiency, there is no absolute guarantee of protection for any particular individual.
WHAT DOES THIS MEAN IN THE REAL WORLD?
There is a difference between efficacy rates obtained in clinical trials and effectiveness: the real-world protection rate of a vaccine when it is released.
“Efficacy says, ‘Does it work?’ Efficacy says: ‘Can it be applied? Can you bring efficiency to people? ‘”, Said
Marcel Tanner, epidemiologist and president of the Swiss Academies of Arts and Sciences.
In the real world, the effectiveness of a vaccine can be influenced by multiple unpredictable factors including, for example: the rate of spread of a virus; how many or few people adhere to the optimal dosing schedule and schedule; how people’s immune systems respond; if the vaccine was stored at the correct temperature; whether or not people know if they have been exposed before.
Generally, the effectiveness of a vaccine in the real world tends to be slightly less than its effectiveness.
WILL THESE VACCINES STOP THE COVID-19 PANDEMIC?
Experts say this is unlikely. More realistic, they say, is that we will have to live with the SARS-CoV-2 virus.
The evidence so far suggests that the COVID-19 vaccines developed by Pfizer-BioNtech, Moderna and AstraZeneca it will help prevent people from developing the disease. Only AstraZenecaThe data so far show signs that your injection may also help prevent transmission of the virus.
“Protection against disease has value to the individual,” said Penny Ward, visiting professor of pharmaceutical medicine at King’s College London. However, he added that vaccines that do not prevent transmission will not stop the pandemic.
“Until vaccination and other measures result in the virus being close to elimination in any particular country, and around the world, distancing, masks, and hand washing will continue to be necessary to reduce transmission more than is expected. it will achieve with the vaccine alone ”. said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine.
“(A) vaccine is not good until people are vaccinated, and even then, it will not result in a situation where all other protective measures can be immediately abandoned.”
– Information from Kate Kelland in London and John Miller in Zurich; Edited by Kevin Liffey
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