A single dose of AstraZeneca or Pfizer / BioNTech COVID-19 vaccine reduces infection by 65% ​​| 2021-04-27

London – A large UK study examining the antibody response of 373,402 people in the general population and the impact of COVID-19 vaccination on new infections shows that a single dose of the vaccine reduced infections by 65%. I did.

Twenty-one days after receiving either initial dose, symptomatological infections decreased by 74% and asymptomatic infections decreased by 57%. AstraZeneca plcOr Pfizer Japan Inc/BioNTech SEVaccine.

Twenty-one days after the second dose of the Pfizer / BioNTech vaccine, symptomatic infections were reduced by 90% and asymptomatic infections were reduced by 70%. This is similar to the effect seen in people who have previously been naturally infected with COVID-19.

Deployment of the AstraZeneca vaccine was later initiated in the United Kingdom and there are no data yet on what will happen after the second dose of this product.

Both vaccines were first detected in the United Kingdom in December 2020 and are now effective against the B.1.1.7 variant of the virus, which is responsible for most infectious diseases throughout Europe and the United States.

This is because B.1.1.7 was not in circulation when clinical trials were conducted and there were some in vitro data showing that variants could reduce the efficacy of the two vaccines. It is important.

These findings on vaccine efficacy are based on 1.61 million PCR tests performed on nasal and throat swabs from December 1st to April 3rd, 2021. Participants from randomly selected households across the UK were visited and wiped with cotton swabs at home.

The national vaccination program started on December 8th.

“The main advantage of this study is [PCR] Koen Pouwels, senior researcher at the Faculty of Population and Health at Oxford University, said:

The fact that the reduction in asymptomatic infections was smaller than in symptomatic infections highlights the potential for people to become infected with COVID-19 after vaccination. This indicates an ongoing risk of transmission from vaccinated individuals “even at lower rates,” Pouwels said at a news conference. “This emphasizes that everyone must continue to follow the guidelines to reduce the risk of infection,” he said.

Without a large community study, “it is impossible to estimate the effects of vaccination on asymptomatic infections. These mistakenly say that especially vaccinated people cannot catch COVID-19. If you think about it, it could continue to be epidemic, “said Sarah Walker, a senior researcher at COVID in the UK and a professor of medical statistics and epidemiology at Oxford University. 19 Infection investigation.

Of course, the key question is whether the vaccine alone can control the pandemic. In the UK, new infections fell from 60,000 per day during the peak of the second wave in mid-January to 2,729 on April 21. However, most of the time, strict national social distancing and other control measures were in place. place.

According to Walker, the findings are “carefully optimistic” in controlling what she said the vaccine was endemic rather than a pandemic. “Long-term blockade is not a viable solution. Vaccination is the only way you can control it in the long run,” she said. But she also warned that “the virus could give us a curve ball,” as the examples in India, Canada and Brazil show.

Immune response

Infection studies have randomly tested individuals for SARS-CoV-2 infection since April 2020. We are currently processing 3.9 million swabs and 300,000 blood tests. Blood tests are currently being enhanced to allow a more detailed examination of the immune response to viruses and vaccines.

Based on clinical trial data, vaccine makers claim that their products are 100% effective in preventing serious illness and death. However, researchers said it was impossible to confirm this from their studies.

By testing antibodies against the viral peplomer, which is induced by both natural infections and vaccines, and antibodies against nucleocapsid, which occurs only later, the effects of vaccination and natural infections on the immune system can be elicited. Natural infection.

Antibodies to peplomer were found in 45,965 participants after vaccination. “The main message is that there was a strong antibody response. [after vaccination] David Eyre, an associate professor at the University of Oxford’s Big Data Institute, said:

The strongest response was in young people, but all age groups had an immune response, which was maintained until the 10-week cutoff of the tranche of this data. Antibody levels rose from day 1 to day 14 and then leveled off.

Antibodies peaked earlier than AstraZeneca’s product after Pfizer / Biontech vaccination, but then declined slightly, resulting in the same antibody titers for both vaccines 7 weeks after vaccination.

Eyre said it was good “in the context of a 12-week interval” between the first and second doses selected by the United Kingdom to maximize the public health benefits of the limited supply of vaccines.

This study will continue to track the immune response to vaccination to see how long the antibodies last and whether they are effective against the mutants of concern.

However, Walker pointed out that the level of infection in the United Kingdom is currently very low, reducing the power of research to detect its effects. Sufficient evidence should be provided to indicate when booster immunization of the vaccine is needed and when / when represcription is needed to protect against mutations of concern.