COVID-19 Vaccines FAQs
Vaccine makers must follow very strict scientific and health authority processes to bring a new vaccine to the public, even during the current pandemic.
With vaccine development moving so quickly, it is understandable why some people are asking whether a vaccine for COVID-19 will be safe and effective (work well).
Phase 3 clinical trials (last and largest phase of vaccine testing before authorization or approval) test how effective a vaccine is at preventing COVID-19 and are being conducted with tens of thousands of volunteers around the world. During Phase 3, some volunteers get a COVID-19 vaccine and some get a “placebo”. A placebo is a harmless injection with no active drug or treatment, for example, like normal saline.
To learn how effective a vaccine is at preventing a specific disease, researchers assess the vaccine efficacy rate which compares:
- The number of volunteers who got COVID-19 after getting the vaccine being studied.
- The number of volunteers who got COVID-19 after getting a placebo.
Thousands of people have volunteered to take part in different COVID-19 Phase 3 trials around the world. Some of these trials reported vaccine efficacy rates of over 90%.
All of the authorized COVID-19 vaccines go beyond the FDA’s minimum efficacy level of 50%. In other words, the FDA would not authorize a vaccine unless it prevented COVID-19 or lessened its severity in at least 5 out of 10 (50%) of people who got the vaccine.
After a vaccine is authorized, health authorities continue to monitor its safety and effectiveness.
After receiving a vaccine, your body’s immune system needs a little time to learn how to detect and fight the virus. This maturation of the immune system can vary but is usually around a few weeks. Each authorized or approved COVID-19 vaccine has different speeds for how quickly it protects you. The speed of response can depend on factors such as the dosing schedules or the number of doses.
Based on clinical trial data of the currently authorized or approved COVID-19 vaccines, optimal protection is reached within a few weeks of vaccination. For two-dose vaccines, some early protection is achieved after the first dose.
It is too early to know how long COVID-19 vaccines will provide long-term protection. More research is needed to answer this question.
The currently available data suggest that most people who recover from COVID-19 infection develop an immune response that provides at least some protection against reinfection (getting it again) – this is called natural immunity. We’re still learning how strong this natural immunity may be, and how long it lasts.
Health authorities will continue to monitor the clinical trial volunteers for many months to check how long they are protected. Both natural immunity and immunity from a vaccine are important aspects of COVID-19 that experts are trying to learn more about.
Maybe. Clinical trials have shown that COVID-19 vaccines significantly lower the chance a person will have symptoms, including hospitalizations and severe symptoms. However, none of the COVID-19 vaccines tested so far have been 100% effective at preventing COVID-19. So, some people who get the vaccine may still get COVID-19.
Furthermore, we still do not know if the vaccines will prevent someone who is infected (but doesn’t have symptoms) from spreading COVID-19 to others. Research tends to show that a vaccinated person is less likely to spread COVID-19 to those who are more vulnerable (have a higher risk of severe COVID-19 infection), similar to what happens with vaccines for other respiratory infectious diseases such as influenza.
This is why it remains important to continue washing hands, using social distancing, and wearing a mask even after you get a vaccine. This guidance may change over time as we learn more.
During most COVID-19 vaccine clinical trials, people of different ages took part to confirm the vaccines safety profile and effectiveness in older age groups, who are most at risk of serious illness and death from COVID-19. Extremely frail older persons and persons above the age of 95 years were not included in clinical trials. Most of these trial results showed high levels of effectiveness in different ages groups, including in some cases those over age 65.
When deciding to get vaccinated or not, older adults should remember that they have been disproportionally affected by the COVID-19 pandemic:
- They have a higher chance of needing hospital care or dying if they get COVID-19, compared to younger adults.
- The chance of severe illness with COVID-19 goes up with age, with older adults at the highest risk.
- The greatest risk for severe illness from COVID-19 is among those aged 85 or older.
This is why the World Health Organization (WHO) has identified older adults as a priority group to get the vaccine. While vaccination is recommended for older persons due to the high risk of severe COVID-19 and death, very frail older persons with an anticipated life expectancy of less than 3 months should be individually assessed.
If you have concerns, talk to your doctor about whether or not you should get a COVID-19 vaccine.
According to the World Health Organization (WHO), people with underlying medical problems like high blood pressure, heart and lung problems, diabetes, obesity, or cancer, are at higher risk of having serious illness from COVID-19.
Clinical trials are designed to assess all races, genders, different ages, as well as people with well-controlled underlying health conditions, such as diabetes or heart disease. However, as with other vaccines, clinical trials for COVID-19 vaccines do not include people with a weakened immune system, such as people who are taking chemotherapy or bone marrow treatment. As COVID-19 vaccines are put into widespread use, safety and effectiveness data will continue to be collected, analysed, and reported for all populations, including people with conditions that suppress their immune response.
While COVID-19 vaccination might provide a lower level of protection in people who are immunocompromised compared with the rest of the population, it is still very important to get vaccinated, as well as continue washing hands, using social distancing, and wearing a mask event after getting a vaccine.
Some types of COVID-19 vaccines may be more suitable than others for people with weakened immune systems. If you have concerns, talk to your doctor about whether or not you should get a COVID-19 vaccine.
Viruses often change or mutate. A mutation is when the genetic material in the virus changes. Mutations happen at different speeds in different viruses. They do not necessarily affect how well a vaccine works against a virus.
The scientific community and health authorities are closely watching:
- How the SARS-CoV-2 (the virus that causes COVID-19) changes over time.
- How well COVID-19 vaccines can protect people against COVID-19 caused by any new versions of the virus that appear.
Vaccines against some viruses keep working for many years after their development and provide long-lasting protection. These include vaccines against measles and rubella. Vaccines against other viruses like the flu need to be updated every year to keep working. This is because the flu virus mutates often and with large changes, with new versions appearing each flu season.
Given recent mutations with the SARS-CoV-2 virus, vaccine manufacturers also are beginning research into vaccines against these new strains, in case a new vaccine or booster is needed.
We need COVID-19 vaccines to help make the world safer for our families and for yours.
People who work within the biopharmaceutical industry have been affected by the global pandemic in many of the same ways that everyone else has. They’ve had to deal with loss, balancing work and homeschooling while also supporting family members, parents and friends in unexpected ways. All the while working to help advance science and bring COVID-19 vaccines into the world.
Hear their stories
