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Additional Helpful COVID-19 Resources

General Vaccine Questions

According to the CDC, a vaccine stimulates your immune system to produce antibodies and cellular immunity to combat that specific disease, like it would if you were actually exposed to the disease. After getting vaccinated, you develop immunity to that disease without having to get the disease first. This is why vaccines are necessary — they prevent disease by letting you develop immunity in a safe and controlled way.

Pfizer and Moderna’s vaccines use novel messenger-RNA, or mRNA, technology, which uses genetic material to cause the body to create a protein from the virus, allowing the immune system to recognize the virus and attack it. These will be the first mRNA products to be approved by the FDA. The studies have enrolled 43,538 volunteers and 38,955 have received their second dose. About 42% of global participants and 30% of U.S. participants have racially and ethnically diverse backgrounds. In Pfizer and BioNTech’s late-stage clinical trial, 50% of the volunteers got the vaccine, while the other half got a placebo of saltwater. Then they waited to see who would get sick. Only 170 volunteers out of 44,000 have so far gotten sick with COVID-19. An independent board of experts looked at the placebo group and vaccine participants and reported that the vaccine is 95% effective. See this story to learn more about mRNA vaccines. And this story from Time Magazine gives a great overview. See this infographic for a quick study on how the mRNA vaccine work

The AstraZeneca and University of Oxford team, as well as Johnson & Johnson/Janssen, are also working on vaccines but using different technology for delivering the viral genes that can produce viral proteins to activate the immune system. Novavax and the Sanofi/GlaxoSmithKline are working on a vaccine that uses proteins themselves to trigger an immune response. All are close to completing their testing. For up-to-date information on all the vaccines, please see testing of their shots. To track the vaccine trials, please see this updated tracker in the New York Times.

Current data show that both the Pfizer vaccine and Moderna vaccine are 95% effective in preventing a person from getting COVID-19. The studies did not test everyone to see how many people in the vaccinated group got infected compared with the placebo group. Instead, the scientists compared how many in the vaccinated group and the placebo group went on to develop disease. The companies will continue to test people in the studies for antibodies to the COVID-19 virus, which would include people who did not show any symptoms of their infection, so they can get a better sense of whether or not the vaccines protect against not only getting sick, but also against infection.

These vaccines will require two doses and need to be kept at very low temperatures, much colder than a household freezer. Many hospitals and clinics do not have the ability to store the medicine at these ultra-low temperatures, so that must be worked out. At Houston Methodist, we have ample cold storage facilities to hold whichever vaccine we use for patients and employees. And during distribution we still need to keep the vaccines cold and the temperature strictly monitored, making the distributing challenging. However, Houston Methodist has teams working on our plans for this and we are prepared to store and safely distribute the vaccine we receive. 

Yes, it is. The FDA is expediting clinical trials for vaccines because of the importance to stop the spread of COVID-19. However, the FDA is following its processes and only issued the EUA for the Pfizer vaccine after it determined it safe and that the manufacturer conducted the trials properly. Remember that safety is paramount at Houston Methodist – for both our patients and our staff. We are hopeful that the vaccine will help keep you, your family and our patients safe by keeping you healthy. 

A flu vaccine will not protect you from getting COVID-19, but it can prevent you from getting influenza (flu) at the same time as COVID-19. This can keep you from experiencing a more severe illness. While it’s not possible to say with certainty what will happen in the winter, CDC believes it’s likely that flu viruses and the virus that causes COVID-19 will both spread during that time. You should encourage all of your friends and family to get flu shots, just like we have at Houston Methodist.

No. These vaccines will not cause you to test positive on viral tests, which are used to see if you have a current infection. As your body develops an immune response, which is the goal of vaccination, it is likely you will test positive on some antibody tests. Antibody tests currently indicate you had a previous infection or vaccination and that you may have some level of protection against the virus. Experts are currently studying how COVID-19 vaccination will affect antibody testing results and whether performing these tests are useful in determining an individual’s immune status to COVID-19.

According to the CDC, we won’t know how long immunity lasts until we have a vaccine and more data on how well it works. Both natural immunity and vaccine-induced immunity are important aspects of COVID-19 that experts are trying to learn more about. The CDC will keep the public informed as new evidence becomes available.

In the short term, no. The soonest that coronavirus vaccines could become widely available to the public would be in the spring. But if effective vaccines become available — and if most people get them — the pandemic could drastically shrink. This means we are one giant step closer to getting our lives back to normal. 

Due to the severe health risks associated with COVID-19 and the fact that reinfection with COVID-19 is possible, people may be advised to get a COVID-19 vaccine even if they have been sick with COVID-19 previously. At this time, experts do not know how long someone is protected from getting sick again after recovering from COVID-19. The immunity someone gains from having an infection, called natural immunity, varies from person to person and the evidence suggests natural immunity may not last very long in some people.