If you are fully vaccinated, you may be excited to reunite with family and friends. You can even plan a winter vacation. But there are still compelling questions about how long protection against coronavirus vaccines will last. For example, will you disappear gradually or suddenly? Will you need a booster? “We can only say that a vaccine is protective, as long as we measure it,” said Jamie Meyer, an infectious disease specialist at Yale Medicine, MD. Read on to learn more – and to ensure your health and the health of others, don’t miss it Sure signs that you already have COVID.
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Vaccine life expectancy became a hot topic in August, when some studies began to suggest that the vaccine’s effectiveness was declining, although data also showed that vaccines were still very effective against hospitalization. In a study reported by the Centers for Disease Control and Prevention (CDC), New York State data showed that the effectiveness of the vaccine was reduced from 91.8 to 75% against infection.
Vaccine reduction figures have contributed to the decision to make booster vaccines in the autumn of 2021 – the CDC says all adults 18 and older should receive a booster six months after completing their main vaccination series if they start with Pfizer. BioNTech or Moderna, or two months after receiving a single J&J vaccine. Teenagers aged 16 or 17 can also receive a Pfizer-BioNTech booster, which the FDA approved for this age group in December 2021. The blending and matching policy allows people to take one of the three COVID-19 vaccines available. in the United States as a booster, regardless of which vaccine a person had for their primary vaccination.
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Pfizer and Moderna observed immunity in people who had been vaccinated in the initial clinical trials – both companies reported strong overall efficacy over the six-month period. (Pfizer reports on its effectiveness in a preprint that has not been reviewed by outside scientists; Moderna has released a statement from the company.)
One thing researchers have observed in vaccine recipients is the levels of antibodies, which are proteins produced by the body’s immune system when it detects harmful substances and which are easily measured by blood samples. “Antibodies are a really good marker for protection against infection, so we will monitor these levels until we can measure them,” said Dr. Akiko Iwazaki, a professor of immunobiology at Yale School of Medicine.
Report in The New England Journal of Medicine (NEJM) in April showed that 33 participants who received the Moderna vaccine during the Phase I trial had a gradual decline in antibody protection – and based on inclination, Iwazaki says, this is encouraging news. “If the antibodies decrease very quickly, you expect this to continue for a short time.” The slow decline raises hopes that mRNA vaccines will be protected for at least a year, if not longer, she said. (It should be noted that the test was conducted before Delta became the predominant virus in the United States last summer; by mid-December 2021, Omicron was the predominant virus in the United States)
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Another measure is T cells, which scientists are still studying for their ability to kill virus-infected cells in the context of COVID-19, and which may also provide important protection. T-cells are more difficult to measure, Iwazaki said. But they may be important – last year a study in nature showed that people who were infected with severe acute respiratory syndrome (SARS), a different outbreak of coronavirus that killed nearly 800 people in 2003, maintained T-cell immunity for 17 years after recovering.
Another way to predict how long protection can last is by looking at natural immunity, says Dr. Meyer. This means studying the immunity that people have developed after becoming infected with COVID-19. “We know, at least for the first few months after a symptomatic illness – and even longer – that people are unlikely to become infected again,” she said.
But it is important to know that the immunity caused by mRNA vaccines is stronger and more reliable than natural immunity, Iwasaki said. This is because the levels of natural immunity tend to vary from person to person. “Vaccines normalize the reaction to a very high level, where it raises everyone evenly,” she said. “If you start at a high level, even if you start falling from that level, it will take much longer before you need a booster.”
This is why the CDC recommends vaccinations for people who have had COVID-19 infection as well as for those who have not.
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No one knows for sure whether one vaccine will last longer than another. Instead, one question you need to ask may be whether Pfizer and Moderna’s mRNA vaccines, which have a particularly strong response, also have the potential to be the longest-lasting, says Dr. Meyer.
Both mRNA vaccines use a relatively new technology that delivers a tiny piece of the SARS CoV-2 virus genetic code to the body to provide instructions for making copies of spike proteins that will stimulate the immune response. The Johnson & Johnson vaccine uses a more traditional approach that involves an inactive adenovirus (a common virus that can cause colds and other illnesses when active).
“RNA vaccines are a new tool that has not been widely used with any other virus, and so far in clinical trials they have had a much more stable immune response,” says Dr. Meyer. Whatever the answer to the question of which one will last the longest, the Pfizer and Moderna mRNA vaccines work in a similar way, so they seem likely to have a similar effect on immunity, she said.
However, while both vaccines are still considered highly effective, some recent studies have shown that Moderna is more protective. A study published in The New England Journal of Medicine found that Moderna was 96.3% effective in preventing symptomatic disease in healthcare professionals, compared with 88.8% in Pfizer. Another study conducted by the CDC found that Moderna’s effectiveness against hospitalization was stable for four months, while Pfizer fell from 91% to 77%. But scientists say more data is needed to fully understand the differences between the two vaccines.
“It is also possible that the duration of immunity depends to some extent on the patient,” adds Dr. Meyer. Although more research is needed, there may be variations in human-to-human immune responses based on factors such as age, medical conditions, and medications they may be taking. Overall, however, mRNA vaccines appear to be so effective that they level the playing field for protection against infection, says Dr. Meyer.
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It is extremely important that as many people as possible receive their primary vaccination, says Dr. Meyer. In December 2021, the CDC approved a recommendation to select Pfizer-BioNTech or Moderna vaccines in response to concerns about rare blood clots associated with Johnson & Johnson injection.6254a4d1642c605c54bf1cab17d50f1e
“The good news is that Pfizer and Moderna have made their mRNA vaccines easy to update,” says Dr. Meyer. “It just needs to change a little bit, like computer code that needs a few minor edits. It is relatively easy to set up. ”It is also important to follow the CDC’s recommendations for booster vaccines.
“The hope is that the percentage of cases will decrease and more people will be less likely to be exposed.” This advice is particularly important for the Delta and Omicron variants, which have proven to be more contagious than previous versions, prompting the CDC to issue stricter guidelines urging everyone – vaccinated or not – to wear masks indoors in high-transmission areas. .
Even if Delta and Omicron disappear, “I think these preventative measures will become even more important as the year goes on, because potentially your immunity will diminish over time,” says Dr. Meyer.
Meanwhile, people need to consider the amount of viral activity in their area and what they need to do to protect the immunocompromised, children and others who cannot get the vaccine. “I tell my family, ‘It’s great to be vaccinated. This is wonderful and you will have much more freedom and flexibility. But even vaccines don’t have a 100% guarantee, so whatever you do, you want to keep weighing the risks, ”she said. And to protect your life and the lives of others, do not visit any of them 35 places where you are most likely to catch COVID.
This article was published in Yale Medcine.
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