Two doses Pfizer vaccine Has a greater confrontation effect delta Coronavirus variants and Oxford Jab, but research shows that its efficacy declines faster.
Scientists at the University of Oxford said that after four to five months, the level of protection provided by the two vaccine very similar.
These findings, which have not been peer-reviewed, also indicate that people infected with the Delta variant after the second injection have similar peak levels of the virus as unvaccinated people.
According to the researchers, according to their work, although the jabs did not eliminate the chance of contracting Covid-19, they did reduce the risk and were still the most effective way to ensure protection against the Delta variant, which has been used in the UK. Become the mainstream.
Sarah Walker, professor of medical statistics and epidemiology at the University of Oxford, said: “We don’t yet know how much transmission will happen to people vaccinated with Covid-19 – for example, they may have high levels of the virus in a short period of time.
“But the fact that they may carry high levels of the virus suggests that people who have not been vaccinated may not be as immune to the Delta variant as we hoped.
“This means that getting as many people as possible vaccinated is crucial-whether in the UK or around the world.”
The study was conducted in collaboration with the National Bureau of Statistics (ONS) and the Ministry of Health and Social Care (DHSC), and studied data from December 2020 to August 2021 in the Covid-19 Infection Survey.
The swab tests of more than 700,000 participants were analyzed before and after May 17, 2021, when Delta became the main variant in the UK.
The analysis showed that for infections with high viral load, the protection of Pfizer one month after the second vaccination was 90% higher than that of unvaccinated individuals, which dropped to 85% after two months and 78% after three months.
The researchers said that for AstraZeneca, the equivalent protections were 67%, 65%, and 61%.
Dr. Koen Pouwels, a senior researcher at the Nuffield Department of Population Health at the University of Oxford, said the team “can be confident” that the Pfizer vaccine number “really represents a decline,” while for AstraZeneca, “the difference coincides with chance.” In other words, the protection of AZ has not changed at all.”
But he added: “Even if the protection against all infections and infections with high viral loads drops slightly, it is important to note that the overall effectiveness is still very high, because we start with such a high level of protection.
“It is also worth emphasizing that the data here does not tell us the level of protection against serious diseases and hospitalizations. These are two very important factors for evaluating the effectiveness of vaccines.”
The scientists also found that the effectiveness of a single dose of the Moderna vaccine against the Delta variant was similar or higher than that of other vaccines, but the researchers added that they did not have any data on the second dose of the vaccine made in the United States. .
The study also showed that the time interval between two administrations does not affect the effectiveness of preventing new infections, and that young people (18-34 years old) are more likely to be vaccinated compared with older people (35 to 64 years old). The protection is greater.
The academics said they could not comment on what this study might mean for a potential fall booster campaign, but said the Joint Committee on Vaccination and Immunization (JCVI) will consider the data when making a decision.
NHS officials are ready to provide the third coronavirus injection starting in early September, but have not yet received JCVI approval.
Commenting on the study, Dr. Alexander Edwards, associate professor of biomedical technology at the University of Reading, who was not involved in the study, said: “Overall, this study is excellent because it shows that although Delta is more effective in infecting vaccinated people It used to be a better variant, and the vaccine is still very effective.
“There are subtle differences between the different vaccine types, and some changes will occur over time-but they are all very effective.”
