Three studies, one result: Vaccines show a break from the pandemic

Three scientific studies released on Monday show that widely used vaccines can be adapted to protect people from the coronavirus for long periods of time, perhaps years, and to further strengthen the immune system if needed. Provided fresh evidence.

According to one study, most people immunized with the mRNA vaccine may not require booster immunity unless the virus and its variants evolve far beyond their current form. This is not guaranteed. According to a third report, mixed-and-match vaccination is promising and significantly boosts immunity when booster shots of one widely used vaccine found in the second study are needed.

Scientists were worried that the immunity provided by the vaccine would soon be diminished, or that the rapidly evolving virus would somehow overtake it. Together, the findings renew optimism that the tools needed to end the pandemic are already at hand, despite the rise of new infectious variants that are currently causing a surge around the world. ..

Marion Pepper, an immunologist at the University of Washington at Seattle, said:

Deepta Bhattacharya, an immunologist at the University of Arizona, said: Now that we have all the good news, “it’s hard to understand how and why we need the same booster every 6-9 months,” he said.

The coronavirus may be evolving, but so are the body’s defenders. In a study published in Nature, researchers discovered a vaccine made by Pfizer-BioNTech and Moderna. Causes a persistent immune response in the body It has the potential to protect against coronaviruses for years, as important immune cells continue to develop longer than expected.

Ali Ellebedy, an immunologist at Washington University in St. Louis, and his colleagues reported last month that the immunity of people infected with the coronavirus and later vaccinated could last for years or even a lifetime.

However, it was unclear whether vaccination alone would have a long-term effect as well.

In a new study, his team found that immune cells in the body were still organized 15 weeks after the first vaccination.

The longer these cells have to practice, the more likely they are to block the coronavirus mutants that may emerge. The results suggest that the majority of vaccinated people are at least long-term protected from existing coronavirus variants.

Elderly people, people with weak immunity, and people who are still taking drugs that suppress immunity may need a booster. However, those who survive Covid-19 and are later immunized may not need additional shots because the immune response appears to be particularly strong.

This study examined mRNA vaccines, but did not consider vaccines produced by Johnson & Johnson or AstraZeneca. Dr. Ellebedy said he expects the immune response produced by these vaccines to be less durable than the immune response produced by the mRNA vaccine.

New research suggests that the mix-and-match approach may work equally efficiently. If you have been vaccinated with Johnson & Johnson or AstraZeneca, you may want to choose the mRNA vaccine as your second vaccination.

In a British vaccine study published Monday, volunteers received a single dose of the Pfizer-BioNTech vaccine, a single dose of AstraZeneca, and then produced high levels of antibodies and immune cells.

Dr. Matthew Snape, a vaccine expert at Oxford University, said at a press conference on Monday that vaccination in either order is likely to have a strong protective effect. “I think all of these schedules are controversial, but they are expected to be effective,” he said.

Dr. Snape and his colleagues Started the trial, Called Com-COV in February. In the first wave of research, they gave 830 volunteers one of four combinations of vaccines. Some people took either Pfizer-BioNTech or AstraZeneca twice, both of which have been shown to be effective against Covid-19. Others took one or vice versa of Pfizer after AstraZeneca.

Those who received two doses of Pfizer-BioNTech produced about 10-fold higher levels of antibody than those who received two doses of AstraZeneca. Volunteers who received AstraZeneca following Pfizer-BioNTech showed approximately five-fold higher antibody levels than volunteers who received two doses of AstraZeneca.

Volunteers who received Pfizer-BioNTech following AstraZeneca also reached about the same antibody levels as volunteers who received Pfizer-BioNTech twice.

Another promising result came when researchers examined the levels of immune cells prepared to attack the coronavirus. Mixing the vaccines produced higher levels of cells than two doses of the same vaccine.

Dr. Snape said it was not yet clear why mixing brought that benefit.

Dr. Snape and his colleagues have launched another similar combination trial that includes the Moderna and Novavax vaccines on the list of possibilities. However, he stopped recommending routine mix-and-match strategies. For now, the best course of action is to get the same vaccine twice.

Large clinical trials have clearly shown that this strategy reduces the chances of getting Covid-19. “Your defaults must be proven to work,” said Dr. Snape.

But for many, that is not always possible. Vaccine shipments may be delayed due to manufacturing issues. Young people in some countries are advised not to take a second dose of AstraZeneca because they are concerned about the low risk of developing blood clots.

In these situations, it is important to know if people can switch to another vaccine for the second dose. “This provides reassuring evidence that it should work,” said Dr. Snape.

Despite the promising news that most people may not need booster immunization of the mRNA vaccine, there may be some situations where a third shot is needed. Therefore, vaccine manufacturers have tested booster doses that can be deployed in case of emergency.

The result is good news. Researchers reported on Monday that a third dose of the AstraZeneca vaccine elicited a strong immune response in clinical trial volunteers.

The 90 research volunteers in the UK were one of the first to receive a shot in last year’s clinical trial. In March of this year, about 30 weeks after the second dose, the third dose was given. Laboratory analysis showed that the third dose increased antibody levels to a higher point than was seen even one month after the second dose. Need to provide new protection Even if the first two doses are less effective.

This study was posted online in preliminary preprint format, but has not yet been peer-reviewed or published in scientific journals.

“If it turns out we need it, we must be in a position to help,” Andrew Pollard, a vaccine researcher at Oxford University, said at a press conference on Monday. “I think this preprint has promising data showing that boosters can be used and are effective in boosting the immune response.”

However, availability is severely limited if booster shots are considered necessary within the next few months, especially in poor countries where there is not enough supply to even give the first dose to the most vulnerable citizens. May be done.

Earlier this month, the National Institutes of Health announced that it had begun. New clinical trial person’s Completely vaccinated Use one of three US-approved vaccines. The goal is to test whether booster shots of the vaccine produced by Moderna increase antibodies to the virus. First results are expected later this summer.

The AstraZeneca vaccine has been licensed in 80 countries since December last year, but has not been approved for use in the United States, where there are already three other licensed vaccines in sufficient quantities to meet demand.