The goal of a vaccine is to eliminate or control the virus in your body, which could prevent infection, or control an infection from developing into disease.
The vaccine causes the immune system to respond by looking as much like the invading virus as possible without causing disease itself. Vaccines have been used for decades around the world. While smallpox is the only infectious disease to date that has been eliminated globally by vaccination, vaccines have reduced the burden of many other infectious diseases such as polio, measles, mumps, and pertussis.
Most recently, vaccines for the prevention of human papillomavirus HPV , pneumonia, and shingles have been developed. We are overlapping some of the steps instead of doing them one after the other. With funding from the U. This risk was taken because of the public health crisis.
If the studies show the vaccines are not effective, they will be destroyed. At every stage of the vaccine development process our primary concern is the safety of the public. Long-term safety is still being studied, YES they are safe! Most side effects happen within 7 days of vaccination and last days. More people reported side effects following the second dose. Read more about mRNA vaccines safety and side effects.
Though antibody responses are important to prevent viruses from invading the body, memory B and T cells play a significant role when fighting infection, according to researchers at the University of Pennsylvania.
They followed people fully vaccinated with mRNA vaccines Pfizer or Moderna — some of whom never had COVID and others who had previously had the virus — to measure their immune responses. As expected, antibodies waned over time, but memory B and T cells persisted for at least six months, which might suggest steady and durable protection from severe disease and hospitalization as a result of the virus, according to the Penn Medicine study published in Science.
Waning immunity has been a hot topic in recent months as breakthrough COVID infections, though rare, have been reported, and as boosters have been recommended for certain groups of people whose immune responses become less robust over time. John Wherry, director of the Penn Institute of Immunology, who helped lead the study. But there are other parts of the immune system that can help fight the virus.
The vaccine can also boost memory B cells, which are cells that can make antibodies. They circulate in the blood and are ready to help people fight infections. If a person does get infected, or receives a booster vaccine, those memory B cells quickly become activated, and within a couple days they make a new set of high-quality antibodies to help eliminate the virus and prevent it from spreading around the body.
The immune system also generates memory T cells that detect and tackle viruses once inside the body. But once a virus invades the body, these cells prevent the virus from spreading and from getting deep in the lungs, which could cause pneumonia and severe respiratory symptoms. GOV or call or Date Issued: May 19, The U. However, more research is needed to understand the meaning of a positive or negative antibody test, beyond the presence or absence of antibodies, including in people who received a COVID vaccination, in people who have been exposed and have SARS-CoV-2 antibodies, and in people who are not fully vaccinated.
If you have not been vaccinated: Be aware that a positive result from an antibody test does not mean you have a specific amount of immunity or protection from SARS-CoV-2 infection. When the familiar antigens are detected, B-lymphocytes produce antibodies to attack them. Vaccines help develop immunity by imitating an infection. This type of infection, however, almost never causes illness, but it does cause the immune system to produce T-lymphocytes and antibodies.
Sometimes, after getting a vaccine, the imitation infection can cause minor symptoms, such as fever. Such minor symptoms are normal and should be expected as the body builds immunity. However, it typically takes a few weeks for the body to produce T-lymphocytes and B-lymphocytes after vaccination. Therefore, it is possible that a person infected with a disease just before or just after vaccination could develop symptoms and get a disease, because the vaccine has not had enough time to provide protection.
Scientists take many approaches to developing vaccines. These approaches are based on information about the infections caused by viruses or bacteria the vaccine will prevent, such as how germs infect cells and how the immune system responds to it. Practical considerations, such as regions of the world where the vaccine would be used, are also important because the strain of a virus and environmental conditions, such as temperature and risk of exposure, may be different across the globe.
The vaccine delivery options available may also differ geographically. Today there are five main types of vaccines that infants and young children commonly receive in the U. There are four reasons that babies—and even teens or adults—who receive a vaccine for the first time may need more than one dose:. Some people believe that naturally acquired immunity—immunity from having the disease itself—is better than the immunity provided by vaccines. However, natural infections can cause severe complications and be deadly.
This is true even for diseases that many people consider mild, like chickenpox. It is impossible to predict who will get serious infections that may lead to hospitalization.
Vaccines, like any medication, can cause side effects. The most common side effects are mild. However, many vaccine-preventable disease symptoms can be serious, or even deadly. Although many of these diseases are rare in this country, they do circulate around the world and can be brought into the U. Even with advances in health care, the diseases that vaccines prevent can still be very serious — and vaccination is the best way to prevent them.
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