Israel is warning that a single dose of the Pfizer vaccine is 'less effective than we hoped' against COVID-19, and it could be a blow to the US and UK strategies
Israel's coronavirus chief warned the first Pfizer vaccine dose seems "less effective" than expected.
This may worry the UK and US, which are prioritizing widespread first doses.
Israel has vaccinated a larger share of its population than any other country
The Israeli official leading the country's coronavirus response warned that it is seeing a smaller effect than it hoped after giving a dose of the vaccine.
The nation has had the world's fastest vaccine rollout, and as of January 19 had given a first dose of the Pfizer/BioNTech vaccine to 25.6% of its population, per Our World in Data.
But a note of caution came from Nachman Ash, Israel's coronavirus commissioner, who told Israel's Army Radio that a single dose appeared to be "less effective than we had thought," according to The Guardian.
The vaccine is designed to come in two shots, with the second dose given three weeks after the first in clinical trials. This is how Israel is distributing the vaccine.
But the strategy raises concerns for the UK, which is prioritizing giving people the first dose of the vaccine.Â
This means delaying second doses by as much as 12 weeks so that as many people as possible can get their first dose one. The hope is that partial immunity among many people is better than fuller immunity for fewer people.
And it also could bring concerns for the US, where incoming president Joe Biden plans to release all available vaccine doses to maximise the number of people getting shots, which could result in delays to second doses even though the US plan is to give them all on schedule.
Pfizer says that a single dose of its vaccine is about 52% effective, while getting a second dose makes it around 95% effective.
According to Israel, the single dose appears to only be around 33% effective, a significant loss.
Sir Patrick Vallance, the UK government's chief scientific adviser, told the UK's Sky News that he will look "very carefully" at the level of protection that people are getting.
He did not say that the UK should change its strategy, but that the government would "just need to keep measuring the numbers" as the vaccine is given to people.
UK scientists had said in December that clinical trial data suggested the Pfizer vaccine would be 89% effective around 10 days after one dose.
Vallance said this week that the real-world rate of effectiveness was always expected to be lower than that, but that he doesn't think it will be "as low" as what Israel has reported.
The first dose of the vaccine is not thought to offer any protection until around 10 days after getting the shot, and including those days when trying to figure out how effective the first dose is would drive the numbers down.
It is important to note that the UK is not only using the Pfizer/BioNTech vaccine. It is also using the AstraZeneca/Oxford University vaccine, where studies suggest that a spacing out doses could actually provide more protection.
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Editorial: A single dose of COVID vaccine may help, but it's not sufficient
The Times Editorial Board
Tue, January 19, 2021
The all-important push to vaccinate Americans against COVID-19 faces a true dilemma: Two doses are required for the vaccines available right now. But because Americans — like people in many countries — would not refrain from holiday gatherings and keep their masks on, cases are surging higher than they’ve ever been. A single dose of vaccine would provide significant protection, but it’s not enough for long-term immunity.
The federal government had initially held back millions of doses of the Pfizer-BioNTech and Moderna-National Institutes of Health vaccines to ensure there were enough for second helpings for the initial recipients, who've mainly been healthcare workers and nursing home residents. But it abandoned that strategy in late December and plowed through the reserves, according to the Washington Post — though federal officials didn't share that fact with the states. Instead, they announced last week that they would release the national stockpile of COVID-19 vaccines so that more people could get a first dose, without revealing that the stockpile was empty.
This change of plan was based on officials’ belief that the drugmakers could produce enough vaccine for everyone to receive second doses as recommended, which would be three to four weeks after the first dose. (The vaccines range from fairly effective to very effective after a single shot, at least for a while, depending on which one is used.) It’s a reasonable gambit when so many are falling ill and dying, but it’s not without risks.
If states can't collect and distribute the second doses to their residents in time, we don't know what that might mean for the vaccines' effectiveness. None of the clinical trials included an extended time between doses; in other words, no one knows whether people would be as protected if they had to wait extra weeks for the second dose. Though more spread-out shots work for other viruses, these two vaccines use an entirely novel mechanism. Would the protection last long enough for the second dose and would the two together work as well? Quite possibly. Or not.
There are other concerns if the second doses don’t come through fast. One is that people will be less likely to show up for the follow-up if there’s a longer time period between shots.
“If people do not truly know how protective a vaccine is, there is the potential for harm because they may assume that they are fully protected when they are not, and accordingly, alter their behavior to take unnecessary risks,” the Food and Drug Administration said in a statement this month.
Another possibility: People's trust in the vaccine may erode. Many Americans are still reeling from revised and sometimes contradictory messages that came from federal authorities about masks and other pandemic-related issues; now the message on vaccination is changing as well.
The Pfizer vaccine, which hasn’t been tested for how well it works after just one dose, has been estimated to be a little more than 50% effective at that level — about the same level as many flu vaccines — though some people theorize its actual effectiveness would be much higher. The Moderna vaccine, using the same approach as Pfizer’s, is highly effective, about 85% to 90%, at one dose. Effectiveness is closer to 95% with both doses if they’re given within the recommended window.
Failure to get a second dose, or to get it within a reasonable time, raises another concern among health experts: If the vaccine is effective enough to keep a person from having symptoms but not effective enough to completely fight off the novel coronavirus, partly vaccinated people could act as the incubators for a mutated, vaccine-resistant virus.
Regardless, the current surge left health authorities without much choice. Using all those doses to give one shot to as many Americans as possible represents a real opportunity to save lives now and bring down COVID-19 infection rates for the population as a whole, versus theoretically causing problems down the line.
Getting the vaccines rolling out will require a faster, more effective procedure to distribute the shots than California and most other states have managed so far. But it also means better public education to avoid a situation in which millions of people are walking around only partly vaccinated. The second shot is crucial, and Americans will need to be reminded of this repeatedly.
This story originally appeared in Los Angeles Times.
UK to 'look carefully' at claims vaccine efficacy in Israel has dropped to 33 per cent with one dose
Sarah Knapton
Wed, January 20, 2021
Britain will "look carefully" at claims that the Pfizer vaccine fails to protect as well as expected following research into the first 200,000 people given the jab in Israel, Sir Patrick Vallance has said.
The first real-world data showed the first dose led to a 33 per cent reduction in cases of coronavirus among people who were vaccinated between 14 and 21 days afterwards.
But that figure is far lower than that predicted by the joint committee on vaccines and immunisation (JCVI), which suggested a single dose would prevent 89 per cent of recipients from getting Covid-19 symptoms.
In a radio interview, Nachman Ash, Israel's vaccine tsar, said a single dose appeared "less effective than we had thought" and also lower than Pfizer had suggested, raising fears that giving only one dose will not be as protective as hoped.
Sir Patrick, the Government's chief scientific adviser, said experts would need to "keep measuring the numbers" but added that better immunity would build over time.
Speaking to Sky News, he said: "We need to look at this very carefully. What we know from clinical studies… is that if you take everything from day zero to day 28, then the overall figure is something like 50 per cent protection.
"But of course you don't expect any protection in the first days because your immune system hasn't had a chance to build up and some people may have been infected before they had the vaccine. If you take it from day 10 up to day 21 and beyond, it looks much more like the 89 per cent figure the JCVI gave."
However, Sir Patrick admitted the efficacy is unlikely to be as high as 89 per cent in practice because real-world rollouts of vaccines are often lower than trial results.
The Israeli data also showed that people who received their second dose of the Pfizer vaccine had a six to 12-fold increase, meaning they had far better protection.
The UK Government has been criticised for making people wait up to 12 weeks for a second dose, and even Pfizer has warned that one dose efficacy is around 52 per cent.
British scientists called for Israeli scientists to publish their data so they could check the results.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, said: "It is vital that advice and policy take into account the latest available data.
"However, the reports that have come from Israel are insufficient to provide any evidence that the current UK policy in regard to delaying the second dose of vaccines is in any way incorrect. The details of the different studies have only been released, it seems, at a press conference, the reasons for which are unclear.
"There is a need for at least a pre-print giving the detailed methods and data to understand and interpret these findings. It is not sensible to compare efficacy derived from an observational study of this type which is subject to many biases, with the efficacy derived from randomised trials."
Experts also warned that protection against picking up Covid may be less important than finding out whether it stops hospitalisation and deaths.
Although most trials were not powered to determine that, the early data suggests that some vaccines offer blanket protection against the kind of severe disease that leads to fatalities.
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