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It’s true that these vaccines were developed a lot more quickly than traditional vaccines, but the development wasn’t rushed. Several factors made it possible. Scientists already knew a lot about coronaviruses because they cause other diseases. They also started working on the mRNA technology used in the Pfizer and Moderna vaccines more than 10 years ago with the goal of using it to develop vaccines for new diseases quickly in an emergency. Once the Covid vaccines were developed, researchers went through all the usual steps of testing them, but saved time by doing them in parallel instead of one after the other.
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Vaccination is recommended for people who have had Covid because scientific studies show that that the immunity from vaccination is stronger and lasts longer than the immunity from having the disease. Vaccination also appears to give more protection against new variants of the virus.
Getting fully vaccinated with either the Moderna or Pfizer vaccines are your best protection against severe Covid, hospitalization and death from all strains of the virus. In fact, being vaccinated helps stop the virus from developing new strains. The Johnson & Johnson vaccine appears to be less effective against new variants and we no longer recommend it for most people.
The Moderna and Pfizer vaccines are made with similar technology and provide similar high levels of protection against Covid. These vaccines require two doses several weeks apart.
The Johnson & Johnson vaccine is made with older technology and was designed to require only one dose. Recent studies suggest it is less effective against new strains of the coronavirus. Rare, but potentially serious, side effects have also been linked to this vaccine. For this reason, the Pfizer or Moderna vaccine is recommended for most people.
The Covid-19 vaccines available in the United States have been tested in clinical studies of tens of thousands of people and in real-world observational studies of millions of people. We know from these studies that the available vaccines are almost 100% effective in preventing hospitalization and death from Covid, and that they are also highly effective in preventing most Covid disease and new infections.
The safety and effectiveness of the vaccines is constantly being evaluated. But it’s already clear, after 100s of millions of doses, that it’s far safer to be vaccinated than to risk getting Covid, which can be deadly even to young people.
No. It means that the risk of getting sick from Covid is 95% lower for a vaccinated person compared to an unvaccinated person. The actual risk depends on where you live and the kind of things you do, but for a fully vaccinated person it is much less than 5%.
Yes. Boosters are now recommended after 6 months for all fully-vaccinated people 16 and older. This is because the vaccines' protection appears to decrease over time, especially for new coronavirus variants.
When questions come up about illnesses that might be vaccine related, they are investigated and the public is given detailed information about the risks of taking the vaccine compared to the risks of getting COVID-19.
The most common side effects are similar to the ones many people have from other vaccines: pain or tenderness at the site of the shot and tiredness and flu-like symptoms about a day later.
Some people have developed severe allergic reactions after getting a Covid-19 vaccine. These reactions are rare (less than 5 per million). For your safety, you will be asked about your history of allergy before you are given a vaccine and you will be observed for up to 30 minutes afterward to be sure you are okay. In the unlikely event that you do have a reaction, emergency medical providers will be on site to treat you immediately.
So far, no other serious side effects have been definitively linked to the Pfizer or Moderna mRNA vaccines.
A small number of children and adolescents who got Pfizer or Moderna vaccines have developed inflammations of the heart. This condition is very rare and is still under investigation, but it does not appear to be more common in vaccinated people. Blood clots have been found in some women under age 50 who were given the Johnson & Johnson vaccine. The risk of developing this condition as a result of Covid is greater than the risk associated with vaccination, but in the interest of safety we no longer recommend the Johnson & Johnson vaccine for women younger 50.