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The UK has defended its decision to delay the second dose of vaccines as the best way to fight coronavirus, while several countries are adopting a similar strategy in a race against growing cases and new strains.
Britain’s health secretary Matt Hancock said on Sunday that there was great confidence that the first dose would provide “decent effectiveness” against the virus and that the country’s plan would speed up vaccinations across the country.
“You want to get as many people as possible to have as much protection as possible, as quickly as possible,” Hancock said in an interview with Sky News. “This is the fastest way to save most lives.”
Governments around the world are crushing to review vaccination programs because research shows that strains in the UK, South Africa and Brazil are more contagious or even more lethal than the original virus. And countries are restricting international travel restrictions as scientists assess whether existing vaccines are just as effective against variants.
Supply problems also hinder the vaccine, increasing the pressure to give the first photos to as many people as possible, rather than holding the doses back to end the regimen two ways earlier. Both AstraZeneca Plc. and Pfizer Inc. he said they would not be able to meet delivery targets to Europe in the coming weeks, increasing pressure to expand existing supply. US states have also had to slow down their vaccination efforts due to difficulties in obtaining doses.
France on Saturday recommended doubling the time to six weeks between the first and second shots, concluding that this would lead to at least 700,000 more inoculated people in the first month.
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Switching to longer dosing intervals could double the number of people who receive some protection against the virus in the short term, but are at risk. It is unclear what benefits a single injection of currently available vaccines will offer, and there is a danger that mutations will flourish if immunity drops after a first dose.
French orientation
The new French advice is for the vaccine produced by Pfizer and BioNTech SE, as well as for another provided by Moderna Inc. Pfizer recommends that people receive a second dose within three weeks, while Moderna recommends a second dose within four weeks.
The French movement came after January 21st statement from the US Centers for Disease Control and Prevention that further doses of Covid-19 vaccines may be given up to six weeks later, if it is not feasible to get them within the recommended range. US Food and Drug Administration offered some flexibility for “modest delays”.
Research in Israel, leading the world in vaccinations, shows that two days after the second blow, new infections and hospitalizations both dropped by about 60% from their peak. However, in an encouraging sign for the move to delay the second dose, trends began to change around two weeks after the first shot.
Britain has already extended the maximum waiting time from three weeks to 12 weeks, as the Boris Johnson government is trying to vaccinate 15 million people by mid-February. The UK is also vaccinating with the shot developed by AstraZeneca, which was most effective when administered with a lag of up to 12 weeks.
The UK has already delivered more than 6 million doses, the largest in Europe, and Johnson wrote on Twitter on Saturday that each shot is bringing the UK closer to beating the virus. In France, just over 1 million people have been vaccinated.
Delays in dosing regimes are facing new questions from doctors, with the British Medical Association urging the UK to urgently review its decision, allowing the second dose of the Pfizer-BioNTech vaccine to be delayed.
The BMA said in a statement that it supports the delays up to 42 days, or six weeks, citing international guidelines from the World Health Organization that this could work, but warned that Britain’s plan goes “far”.
WHO guidelines
BMA members are also concerned that, given the unpredictability of the supply, there may be no guarantee that a second dose of Pfizer vaccine will be available in 12 weeks, the group said in a statement.
The WHO said there was no data to support the UK move, but said changes in dosing regimes could be justified in emergencies.
In its recommendation, the US CDC said, there is “limited efficacy data” for Pfizer and Moderna vaccines beyond the six-week interval, according to the guide, but if the second dose is given later, “there is no need to restart the series. ”
(Updates to Israel’s study in paragraph 10)