Published on : 19/02/2021 – 13:56
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Jerusalem (AFP)
The first dose of the Covid-19 vaccine from the pharmaceutical duo Pfizer / BioNtech is 85% effective two to four weeks after its injection, concludes an Israeli study published on Friday, while asking not to give up administering the second dose.
The Hebrew state launched on December 19 a vast vaccination campaign against the Covid-19 thanks to an agreement with Pfizer allowing Israel to quickly obtain millions of doses in exchange for biomedical data on the effect of the vaccine in this country where the medical records of the population are digitized.
So far, 4.23 million Israelis (47% of the population) have received at least the first dose of the vaccine – of which 2.85 million have had the necessary second dose -, according to the Ministry of Health .
If recent Israeli studies have quantified the effectiveness of the vaccine at 95% one week after the second dose, this new study conducted by the Israeli hospital Sheba, and published Friday in the scientific journal The Lancet, estimates it at 85% of two to four weeks after the first dose.
The hospital carried out tests on 9,109 health workers from the start of the vaccination campaign until January 24: 7,214 received the first dose and the other 1,895 did not.
During this interval, 170 people in the total sample contracted the disease, of which 89 were in the group of workers who did not receive the first dose.
By comparing the rates of contamination in these two cohorts – vaccinated and unvaccinated – and the time of their diagnosis, Sheba’s teams concluded that the vaccine was 47% effective between the first and the fourteenth day after the first. dose and 85% between the 15th and 28th day.
“From two to four weeks after the (first) vaccination, there is already a high rate of effectiveness, with an 85% reduction in symptomatic cases”, summarized Gili Regev-Yochay, co-author of this study, during a discussion via internet with journalists.
– 2nd dose –
However, only employees showing symptoms or having been in contact with people who contracted the virus were tested as part of this study.
For Peter English, former director of the public health committee of the Association of British Physicians, the approach of researchers at Sheba Hospital remains “rigorous” although the number of “asymptomatic cases” – that is to say of people who contracted Covid-19 without showing symptoms – could be minimized.
“This study was done on people of working age, so it would be interesting to see a similar study on older people after a dose of the vaccine,” said Deborah Dunn-Walters, professor of immunology at the university. from Surrey, UK.
“These new data should support the UK in its decision to offer the second dose twelve weeks later,” she added.
Faced with the limited availability of doses and delays in deliveries, some countries such as the United Kingdom have decided not to administer the second dose three weeks after the first as recommended by the strict protocol. They want to provide a first dose to as many people as possible, starting with the elderly, in order to protect as many people as possible as a minimum.
“I’m not saying we don’t need the second dose, just that we are already seeing effects” with the first dose, Regev-Yochay said.
“The first dose is already showing strong efficacy and it will only be stronger with the second”, she added, adding that the “big, big, question” remains to know if it also makes it possible to reduce the virus transmission. “We are working on this subject (…) and we hope to have good news soon”.
The effectiveness of the vaccine and the high percentage of its population vaccinated, especially among the elderly, have so far helped to reduce the cases of Covid-19 in Israel, according to the authorities, which paved the way for a deconfinement without however allowing the resumption of international flights, a measure intended to limit the propagation of variants.
© 2021 AFP
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