Without sufficient doses available, public health officials bet that crucial second injections of two approved vaccines could be shifted from the recommended waiting intervals – 21 days for Pfizer and 28 days for AstraZeneca – to 84 days for both.
Government scientific advisers say there is little choice given the explosion in the cases, although they acknowledge that delaying the second dose involves risk. Clinical trials do not test the efficacy of vaccines when administered on such an extended schedule.
When Britain first offered a three-month wait between doses, scientists in the United States, Europe and the World Health Organization sounded dubious.
The Food and Drug Administration said earlier this week that it would be “premature”
On Friday, a spokesman for President-elect Joe Biden said the incoming administration would release almost every available dose of vaccine in the United States after Biden took office on Jan. 20 to deliver supplies quickly to the United States. This move marks a shift from the current half-retention policy to ensure that second doses are available to those who received the first dose.
The spokesman did not say that the plan, which will be set out in detail next week, will lead to a delay in receiving the second doses.
Limited data suggest that a single shot of Pfizer or AstraZeneca vaccines provides some protection against disease. For example, the first shot of the Pfizer vaccine was 52 percent effective in the three-week interval before people received the booster. Similar results were described for the Moderna vaccine, which British regulators approved for emergency use on Friday.
But it is not known how long the defense lasts.
British Health Secretary Matt Hancock said earlier that a 12-week interval between doses would mean that people may be less protected from the virus, but society as a whole will see more people vaccinated faster. This is the main compromise.
Hancock stressed that a single dose should protect most of the severe symptoms of covid-19, which send patients to overcrowded hospitals and intensive care units.
British scientists have largely backed the plan, acknowledging that the country is facing a race between vaccines and the virus.
“It is safest and most prudent to use vaccines in the exact conditions that reflect the experiments,” said Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine. “However, this will never be possible in the real world, and the question is to what extent it is permissible to move outside the exact conditions.”
On Friday, the WHO proposed interim guidelines that partially supported the UK approach, saying the period between the first and second doses of Pfizer could be up to six weeks instead of the recommended three weeks.
WHO experts note that many countries are facing a crisis.
“Countries experiencing exceptional epidemiological circumstances may consider postponing the second dose for a short period as a pragmatic approach to increasing the number of people taking the first dose while the supply of vaccines continues to increase.” says in her directions.
Britain was killed by a third wave of covid-19, powered by a highly transmissible variant of the coronavirus. The country is under another national blockade.
London Mayor Sadiq Khan said on Friday that the new option was raging “out of control” and that hospitals were in danger of being overcrowded.
More than 1 in 20 people in some parts of the capital are infected, Khan said. In England as a whole, 1 in 50 is infected.
A respiratory doctor writes in the Guardian that London hospitals are regulating access to oxygen, and doctors must decide who can be saved.
“This is a national challenge like nothing we have seen before,” Prime Minister Boris Johnson said at a briefing on Thursday when he announced that the British military had been tasked with coordinating the delivery of millions of doses.
So far, the UK has given 1.5 million people the Pfizer vaccine, along with the first doses of the new AstraZeneca-Oxford shot, at the early launch of Johnson, considered the most advanced in Europe. The Moderna vaccine will not be available in the UK until spring.
By mid-February, the government aims to vaccinate the 15 million people in the four priority groups, which include everyone over the age of 70, along with all residents of nursing homes, health workers and first-line workers and those with extreme disabilities. serious medical conditions. Health officials say 88 percent of family deaths occurred in the cohort over the age of 70.
Nilay Shah, head of the chemical engineering department at Imperial College London, told The Washington Post: “The goal is almost achievable, but everything has to go every day.”
Shah said the new campaign would require the UK to increase rapidly to 300,000 doses a day, seven days a week, for 50 days.
The British have been desperately watching in recent months how the government has not kept its promises: it is producing a record number of emergency fans, but only when they were needed; fight in the early months of the pandemic to provide protective clothing for frontline medical workers who instead put on garbage bags; and a repeatedly promising but never delivering “mobile” mobile app to alert users when they have close contact with an infected person.
The prime minister has also been accused of delaying decisions until events catch up. On Sunday, he promised that schools would reopen on Monday. He closed them again on Monday.
By the end of next week, Johnson said, the new campaign will be underway for 1,000 sites operated on by general practitioners; in 223 hospitals and 200 pharmacies; and in seven mass vaccination centers located in sports stadiums and congress halls.
Simon Stevens, chief executive of the country’s National Health Service, a publicly funded health system, said 80,000 workers and volunteers – including retired doctors and nurses – would be deployed.
Stevens said the NHS was also “shamelessly joining the armed forces” to provide logistics.
Brig. Phil Prosser, who has been accused in the past of withdrawing troops and equipment to the battlefield, said “no vaccine program of this size has been made so far.”
He compared the logistics challenge to “creating a large supermarket chain in a month”.
In the UK, much of the blame for the increase in cases is due to the new variant of the virus, which according to research is 30 to 70 percent more contagious.
Jim Naismith, a professor of structural biology at Oxford University, told science reporters: “It’s not really possible to exaggerate how serious this new strain is.”
He warned, “If we fail to reduce the spread of the new strain, then we will probably defeat the NHS.”
To date, there is no evidence that the mutated virus increases the severity of the disease, nor is the new variant expected to affect vaccine efficacy any time soon, although it is also true that viruses change over time and vaccines often need to be changed. to cope.
This finding supports the expectation of many scientists that the immune response elicited by vaccines will be broad enough to counteract highly contagious mutations. The study, led by researchers at the University of Texas Medical Branch, was published Thursday but has not yet been reviewed.
More experiments and direct tests on both options over the next few weeks will bring more clarity, scientists say. British scientists will also monitor the effectiveness of the new dosage regimen.
Carolyn J. Johnson of Boulder, Colorado, and Sioban O’Grady of Washington contributed to this report.