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Scientists are testing whether a fourth shot – that is, a second boost – is necessary

Earlier this month, US public health officials took a strong stance on COVID-19 booster shots – telling the public that, if they’re eligible, get one for protection. against highly infectious diseases. omicron variant. As of December 28, 2021, more than 66.4 million Americans have received a booster shot.

However, while a booster campaign continues in the US, scientists in Israel are studying the possibility of a so-called “fourth” shot – that is, an extra shot after two vaccines. doses and a booster shot – could be the key to boosting immunity against COVID-19.

Such developments are not unprecedented in the world of vaccines. SARS-CoV-2, the virus that causes COVID-19, appears to be part of a flu-like virus to which the body’s immune system cannot maintain permanent immunity. This is called transient immunity, in contrast lasting immunity, caused by infection or vaccination with viruses such as measles or chickenpox. The flu, on the other hand, requires an annual vaccination, because the body’s immune system periodically forgets how to protect against the flu virus, and also because the flu virus changes from year to year.

Indeed, the recommended fourth dose – or second booster, if you prefer – for COVID-19 is somewhat similar to the need for annual vaccination against influenza, and may be needed because of similar immunological reasons.

Therefore, earlier this month, the Centers for Disease Control and Prevention (CDC) officially changed its instructions for those who have received two doses mRNA Vaccines against covid-19. Everyone over the age of 16 who received a second dose more than six months ago is now eligible for a third dose. Some workplaces and university settings are now requiring that to be considered fully immunized, a booster shot is required. Restaurants in San Francisco is requiring a booster for entry.

This guide is directed towards the biological characteristics of the dominant new omicron variant. Indeed, early studies suggest that the current COVID-19 vaccine requires three doses provide full protection against omicrons. While the conventional two-dose regimen still works, the Pfizer booster increases antibody levels by 25 times, and a Modern booster increases antibody levels 37 times.

But while Americans are still getting used to the idea of ​​a third booster, researchers in Israel are weighing whether a fourth might be needed to stop COVID-19 from working.

On Monday, Israeli scientists launched a small study to test the safety and effectiveness of a fourth dose in 150 medical professionals who have received the third dose of Pfizer-BioNTech vaccine at least four months. before. The study comes after a panel of medical experts advised the Israeli government to give a fourth shot to people over 60, immunocompromised people and healthcare workers. Although the Isareali Ministry of Health has yet to approve and implement the recommendation, this study is a step towards a formal recommendation. As Israel is a global leader in third shot research, all eyes are on Israel to see if this is a preview of our future. Several other countries, Germany and the UK, are also considering a second boost.


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Adam Finn, a member of the UK’s Joint Committee on Immunization and Immunization, said: “I think there will probably be people who will get a fourth. According to The Guardian. “Whether that’s everyone, I think, is still very much in doubt… we need to see how things go through this wave and beyond.”

So is there a future fourth attack on the United States? Some experts do not believe it is necessary.

“Then you have to ask yourself, ‘What is the goal?'” LJ Tan, chief strategy officer of Immunization Action Coalition, told Salon. If the goal is to “reduce hospitalizations, reduce systemic growth, and reduce the number of critically ill,” Tan advises that goal is to get everyone a booster shot before a fourth dose is given. .

“But if the goal is to stop transmission and prevent people from passing omicrons from person to person, then a fourth dose is probably needed,” he added. Tan isn’t sure if there’s data to say a fourth dose will be helpful, but said he’s pleased to see a clinical trial underway and eager to see what it will reveal.

In the Israeli trial, participants had to have an antibody count below 700. A medical professional who received the fourth shot said he wanted to protect his heart transplant patients, according to the Washington Post.

“The idea is before the government decides whether to launch another vaccination campaign, to test the effectiveness of the vaccine,” said Steve Walz, a spokesman for Sheba Hospital where the research is being done. this vaccine.

Moreover, data from UK showed that the protection against symptomatic Covid caused by the omicron variant, powered by the booster, could wear off within 10 weeks.

Tan told Salon that there is still a lack of data on omicrons and virulence (meaning its severity) to make the case that three injections are not effective enough – as Tan has previously said, depending vaccination target.

“There’s not a lot of data to show that three doses, which means two doses plus boosters, will have absolutely no effect on omicrons,” said Tan. “Actually, the data would suggest that it’s ineffective at preventing transmission, but [the data] suggests that it is effective in preventing serious illness. “

Tan added, “when you combine that with the suspicion that omicrons are more infectious but less virulent or less severe, you have to ask yourself, ‘What’s the goal?'”

As scientists learn more about omicrons, time will tell whether a fourth dose is needed. Initial data from the Israel study is expected in the coming days and weeks.

What we know about omicron

https://www.salon.com/2021/12/28/scientists-are-testing-whether-a-fourth-shot–meaning-a-second-booster–will-be-necessary/ Scientists are testing whether a fourth shot – that is, a second boost – is necessary

Caroline Bleakley

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