While the availability of the new COVID-19 vaccines is spreading hope and optimism for some, especially individuals and industries hit hard by the pandemic, others are erring on the side of caution. Skeptics want to know, Are they safe? Should I get vaccinated? If so, when can I get it, and can I choose which one? In order to ease these valid concerns, it helps to first understand what the COVID-19 vaccine is, how it works and the development process.
1) What is the COVID-19 vaccine?
By definition, vaccines are substances that help to protect against and prevent certain illnesses. Currently, there are two types of vaccines available for COVID-19, messenger RNA (mRNA) vaccines that include the Pfrizer-Biotech and Moderna vaccines, and a viral vector vaccine, made by Johnson & Johnson.
Messenger RNA (mRNA) vaccines, considered to be a new type of vaccine, have been developed and implemented for earlier coronaviruses like SARS and MERS. Instead of putting weakened or activated germs in the body like traditional vaccines, the mRNA vaccine teaches cells how to make a protective protein. Should the real virus enter the body, that new protein triggers an immune response that produces antibodies and prevents us from getting sick.
Viral vector vaccines piggyback the instructions to fight the coronavirus onto a separate and different virus, called an adenovirus. The virus is not alive and therefore cannot infect the individual receiving the vaccination. Viral vector vaccines have already been used to fight a number of diseases, including Zika, influenza viruses, HIV, malaria and Ebola.
Both Vaccines Had a Blueprint
The existing “blueprints” from previous vaccines enabled vaccine manufacturers to develop the COVID-19 vaccine with greater efficiency and effectiveness. Dr. Patricia Toro, MD, MPH, associate medical director of Harvard Pilgrim Health Care and an infectious disease specialist, notes that this was one of several reasons they were able to develop these vaccines in “10 months versus 10 to 15 years.”
2) How were the vaccines developed and authorized?
All vaccines are required to go through extensive testing before they’re approved or authorized for emergency use by the U.S. Food and Drug Administration (FDA) and introduced to the public. With prioritized funding and resources, and trials running in parallel, the COVID-19 vaccines went through the same clinical development process as all other new vaccines, just in a much shorter time frame. The World Health Organization breaks down new vaccine development as follows.
The vaccine is administered to a small number of volunteers to test for 1) safety, 2) efficacy (does it generate an immune response?) and 3) the appropriate dosage. In this phase, vaccines are typically tested on young, healthy, adult volunteers.
Then the vaccine is given to several hundred more volunteers to further determine its safety and ability to generate an immune response. Participants in this phase generally have the same characteristics (such as age and sex) as the intended audience of the vaccine, and there are usually multiple trials to evaluate different age groups and formulations of the vaccine.
Next, the vaccine is administered to thousands more volunteers and compared to a control group to determine effectiveness and safety in a larger number of volunteers.
After a vaccine has completed all three clinical development phases, typically the company that has developed the vaccine will submit a Biologics License Application (BLA) to the FDA seeking approval to market and distribute in the U.S.
Recognizing the COVID-19 pandemic as a public health emergency, however, vaccine manufacturers instead submitted an Emergency Use Authorization (EUA) request to the FDA, which enables the vaccines to be distributed to the public prior to receiving FDA approval. In order to authorize an EUA, the FDA must first rigorously evaluate all the data available and then determine that the potential benefits outweigh the potential risks. After an EUA has been issued, as it has with the COVID-19 vaccines, both the vaccine manufacturer and the FDA continue to closely monitor the vaccines as more data becomes available.
3) Should I get vaccinated – and if so, should I be picky about which vaccine to get?
The CDC reports that current data shows the vaccines are highly effective. In every Phase 3 study for these vaccines, no individuals died of COVID-19 if they received the vaccine, which is a key metric of effectiveness. The mRNA vaccines prevented any kind of symptomatic infection about 95% of the time. Meanwhile, The Johnson & Johnson vaccine prevented any symptomatic infection 72% of the time in the U.S.
There are two contributing factors as to why the results differ:
- The Johnson & Johnson vaccine was tested in different countries than the mRNA vaccines, with different populations. In particular, it was tested in Brazil and South Africa while the variant coronaviruses were the dominant strains. The mRNA vaccines were not tested against variants.
- The Johnson & Johnson vaccine was also tested at a different time during the epidemic. The background transmission rate may have impacted the final efficacy results. On the most important metric, the Johnson & Johnson vaccine was 85% successful in preventing illness that required hospitalization. And again, no one who received this vaccine died in the Phase 3 trial.
Bottom line–the best vaccine to get is the one that’s available to you the soonest. Getting vaccinated can help protect you from getting sick, and early evidence suggests that vaccination may decrease your risk of transmitting the virus if you are infected.
4) When can I get vaccinated?
While COVID-19 vaccines are currently available in all states, availability continues to be limited and priority groups’ eligibility is still being determined by each individual state. For the latest on Connecticut’s vaccination rollout and eligibility, visit the CT Vaccine Portal.
Harvard Pilgrim members can stay up to date on information about the vaccine rollout in our guide to COVID-19 care.
While there’s a lot we now know and can prepare for with the COVID-19 vaccines, there is still so much that’s consistently changing. Over the next few months, closely follow the new developments and changes in availability. And remember that we are still in a pandemic, so for the protection of yourself and others, wear a mask and keep up the physical distancing.
Update as of April 13, 2021: The U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) have recommended a pause in the use of the Johnson & Johnson (J&J) COVID-19 vaccine. The agencies are reviewing data tied to six cases of a rare and severe type of blood clot in combination with low levels of blood platelets among individuals who received the J&J vaccine. While these events seem to be extremely rare, the CDC and FDA are recommending a pause in using the J&J vaccine out of an abundance of caution. Please contact your health care provider if you have received the J&J vaccine within the last three weeks and develop severe headache, abdominal pain, leg pain or difficulty breathing. We will continue to monitor and provide updates as the situation evolves. Please visit the CDC’s website for additional information. [cdc.gov]
