A health worker shows off a bottle of AstraZeneca-Oxford’s Covid-19 coronavirus vaccine at Patan Hospital near Kathmandu on 27 January 2021.
PRAKASH MATHEMATICS | AFP | Getty Images
The results of a new study found that the UK’s decision to delay the second admission of the AstraZeneca University of Oxford coronavirus vaccine.
Researchers at the University of Oxford found that the Covid-19 vaccine was 76% effective in preventing symptomatic infection for three months after a single dose, and that its effectiveness increased with a longer interval before the first and second dose. .
“The efficacy of the vaccine after a single standard dose of vaccine from day 22 to day 90 after vaccination was 76% … and a modeled analysis indicated that protection did not decrease during this first period of three months,” has the study, under the supervision of The Lancet medical. journal and published Tuesday as a pre-print, found.
The efficacy rate increased to 82.4% when there was an interval of at least 12 weeks before the second dose. When the second dose was given less than six weeks after the first dose, the efficacy rate was 54.9%.
“These analyzes show that higher vaccine efficacy is obtained with a longer interval between the first and second dose, and that a single dose of vaccine is very effective in the first 90 days, providing further support for current policies,” the report reads. .
The UK’s current strategy is to first vaccinate as many people as possible with a single dose and to delay the second dose to 12 weeks; the idea is that a first dose provides at least partial protection and that more people can access the vaccines while they are restricted.
The decision to delay people taking a second booster dose has sparked controversy, and some have questioned whether it could lower the vaccine’s effectiveness in preventing serious Covid-19 infection.
However, the UK’s Joint Committee on Vaccination and Immunization supported the approach. The UK is also delaying the second dose of Pfizer-BioNTech vaccine, a step the vaccine manufacturers have warned against, arguing that there is no data to support the delay.
The study also provided important data on whether the vaccine reduces the transmission of the virus, a previously unknown and important question for policymakers to lift the closure measures that have crippled the economy.
Based on weekly volunteers’ swabs in the UK study, it found a 67% reduction in transmission after the first dose of the vaccine.
Effective strategy
This latest study supports the UK Government’s decision and concludes that vaccination programs “aimed at vaccinating a large proportion of the population with a single dose, with a second dose being given after a period of given three months, an effective strategy is to reduce disease, and this may be best for the deployment of a pandemic vaccine when stocks are limited in the short term. ‘
The study used further data on ongoing clinical trials with the vaccine. A separate announcement from AstraZeneca on Wednesday showed that the vaccine also prevents serious Covid-19 diseases, with no serious cases and no hospitalization more than 22 days after the first dose.
The vaccine was approved by the UK Drug Regulator on December 30 and forms a shot produced in Britain, the bulk of the country’s vaccination program, which has so far been considered a success.
The UK is on track to get its top four priority groups (over 70s, residents and staff in aged care homes, health and social care workers and clinically extremely vulnerable) vaccinated, which number about 15 million people by mid-February.
As of February 1, more than 9.6 million people had received a first dose of the vaccine, and just under 500,000 had received two doses, according to government data.
Professor Andrew Pollard, lead researcher on the Oxford vaccine trial and co-author of the study, said this new data is important evidence of the interim data used by more than 25 regulators, including the MHRA and the EMA to to allow the vaccine. authorization for emergency use. “
“It also supports the policy recommendation given by the Joint Committee on Vaccination and Immunization for a 12-week period with a prime boost, as they seek the optimal approach to execution, and assures us that people are protected from 22 days after a single dose of the vaccine. “
The researchers also hope to report data on the new coronavirus variants in the coming days, and expect the findings to be broadly consistent with those already reported by co-vaccine developers: that current vaccines do work against mutations in the virus.
Germany, France and Sweden currently do not recommend the AstraZeneca vaccine for those over 65 and say there are not enough trial data on this age group. However, the vaccine manufacturer and the UK government have defended the gap and according to the available data, it appears to be safe and effective, with more analyzes to be available soon.