mRNA stands for messenger ribonucleic acid. mRNA is a genetic sequence that provides the blueprint for something to be developed in a cell (generally a protein).
The new COVID-19 mRNA vaccine contains a small piece of genetic material created in a lab. This mRNA creates a blueprint for a small part of the SARS-2-Coronavirus called the “spike protein.” This is the part of virus that causes the immune system to recognize that it needs to make antibodies toward this virus.
The mRNA vaccine CANNOT cause an actual infection, as the only part of the blueprint is for the spike protein, and not for the actual virus itself.
The mRNA from the vaccine does not enter the nucleus of the cell (where your DNA is stored), so it cannot change your DNA.
mRNA is quickly read by ribosomes (proteins in the cell) and translated into the spike protein that leads the body to develop antibodies. It is broken down immediately after the cell makes the spike protein. In fact, mRNA breaks down very quickly in general and is not stable for long at normal temperatures, which is why there are such strict storage requirements for some of these vaccines. For example, the vaccine from Pfizer must be stored at -70°C to be stable longer- term. Once refrigerated, it is only good for 5 days, and at room temperature for only about 12 hours.
This is one of a number of false rumors circulating around social media. There is no evidence suggesting that this is a possibility. Further information on this particular rumor, including its origins, can be found here
The mRNA vaccine does not require the use of eggs or any other cells in the production or manufacturing process. Therefore, egg allergy is not a concern with this vaccine.
The mRNA vaccine process is entirely cell free. No living organisms or cells are needed in the manufacturing process.
There are numerous factors that led to this vaccine being produced in a record time. Many of these are listed below:
- The sequence of the virus was published in January 2020, and mRNA was able to be produced within 1 week of the virus genome being published.
- mRNA vaccines are much easier to produce than other types of vaccines. Fewer steps are required in the manufacturing process, allowing manufacturers to produce a larger volume more quickly.
- mRNA technology for vaccines already exists, and mRNA vaccines for other diseases, including influenza, RSV, Rabies, and Zika virus, are also currently in clinical studies.
- Many people volunteered to participate in trials, which allowed them to be started quickly.
- Manufacturing of the vaccine was heavily underway before the approval process had been completed. This is because federal government agreed to pre-purchase a large number of vaccine doses that were strong candidates. Therefore, for companies developing the vaccine, there was less concern about losing money from manufacturing vaccine that would not be used.
Vaccines for COVID have received higher priority than many vaccine candidates for other diseases, which means that more resources have been dedicated to this process, such as ensuring that data related to this vaccine are reviewed rapidly.
More than 40,000 people were part of the Pfizer vaccine trial. Nearly 40% were between 56 and 85, and there was a diverse patient population spanning 6 different countries enrolled.
More than 30,000 people were part of the Moderna vaccine trial, all of whom were in the United States. More than 7,000 patients were over 65, and 5,000 were under 65 but had high-risk chronic conditions. This study also had a very diverse patient population that is fairly similar to the diversity of the US population.
Both vaccines have an efficacy rate of nearly 95% after the 2nd dose. This means that at the time the initial results of the study had been completed, nearly 20 times as many people had become infected with COVID-19 in the placebo group compared with the study group. In the case of the Pfizer vaccine, this was 162 infections in the placebo group and 8 infections in the study group.
Data from the Pfizer trial shows that strong protection from the virus can start to be seen 10-14 days after the first vaccination. After 10-14 days from the first vaccination, very few people were infected with COVID-19, while the placebo group cases rose steadily over time.
Vaccine effectiveness was excellent regardless of age, race, or sex.
The Moderna vaccine is also highly effective among all groups and has a similar timeline of when strong protection from COVID-19 can be expected. Although there is potentially slightly lower efficacy of the Moderna vaccine in patients 65 and older based compared with those younger than 65 based on raw percentages, the number of overall cases in the over 65 group was too small to determine if there is a true difference.
The number of antibodies produced after the second vaccination dramatically increases compared to receiving only a single dose. While a single dose certainly offers some protection, the second dose is expected to offer significantly longer protection.
The most common side effects are similar to what may be expected from the influenza vaccine.Headache, fatigue, fever, muscle ache, and joint pain were among the most common. Pain at the site of injection is also common. Most of these reactions can be managed with acetaminophen or ibuprofen. They may be uncomfortable, however.
In reality, we should think of most of these reactions not as “side effects” and more “immune response.” We expect these types of reactions to occur when our immune system responds appropriately to this type of vaccine.
Higher rates of side effects/immune response were typically seen after the follow up injection, compared with the initial injection. The Pfizer vaccine requires a 2nd dose about 21 days after the first dose, while the Moderna vaccine requires a second dose about 28 days after the first dose.
Of events that were classified as severe and systemic, all were less than 2% except for fatigue (3.8%) and headache (2.0%), specifically after the second dose.0.2% of patients in the vaccine group and 1.0% of patients in the placebo group developed a fever between 38.9°C and 40°C (102°F to 104°F).
There have been reports of a very small incidence of significant allergic reactions to the Pfizer vaccine. Patients who have a history of anaphylaxis to previous vaccines or other injectable medications should not receive the vaccine at this time. Medications necessary to treat allergic reactions will be immediately available at all Deaconess vaccination locations.
Most significant side effects have been related to the reaction that our immune system produces in response the vaccine. These are similar to what how we feel when we are ill. Of events that were classified as severe and systemic, all were less than 2% except for fatigue (3.8%) and headache (2.0%), specifically after the second dose.0.2% of patients in the vaccine group and 1.0% of patients in the placebo group developed a fever between 38.9°C and 40°C (102°F to 104°F). There were no reports of additional severe side effects that are higher than the baseline rate in the general population in the vaccine group compared to the placebo group.
More information regarding the rate of significant adverse effects related to immune response (headache, fever, etc) will be updated when an official publication for the Moderna vaccine is available. Fairly high rates of headache, muscle and joint paint, fatigue, chills, nausea/vomiting, and fever were seen in patients receiving this vaccine.Nausea and vomiting were uncommon among Pfizer vaccine recipients.
There have been several cases of Bell’s palsy reported in both vaccines. This number is higher than the placebo group. However, over the course of one year, the number of patients in a 20,000 patient sample (the size of the Pfizer vaccine group), who would be expected to develop Bell’s palsy would be approximately 3 to 6, assuming no effect from the vaccine. In the study, four patients who received the Pfizer vaccine developed Bell’s palsy compared to none in the placebo group; three patients who received the Moderna vaccine developed Bell’s palsy compared to one patient in the placebo group.
Bell’s palsy is generally considered to be a temporary condition that may resolve with or without treatment. It should be noted that the annual incidence of Bell’s palsy is between 15 and 30 per 100,000 people per year.
There have been two cases of anaphylactic reactions reported out of the United Kingdom (out of thousands of doses) after the first day of vaccination. Both of these patients had a history of anaphylaxis. In the US, the rate of anaphylaxis to the COVID vaccine based on documented events is between 1:40,000 and 1:50,000.
Current guidance from ACIP (American Counsel on Immunization Practices) is for patients who have a history of severe allergic reactions (such as anaphylaxis) to vaccines or other injectable medications to avoid receiving the COVID-19 vaccine from Pfizer at this time. Also, this reaction typically occurs shortly after receiving the vaccine, which is why recipients are instructed to wait no less than 15 minutes after receiving the vaccine.
Of note, there are follow up visits for all the patients in the trials scheduled for up to two years after completion of vaccination, and given the very large patient population in these studies, we should have an even better idea if there are any rare events that occur over time.
Very young, very old:
- Only patients 16-85 years of age were included in the initial vaccine trial.
- Less than 200 patients who were 16-17 years old have received the vaccine at the time of study data cutoff.
- Patients 12 and older started to be enrolled in October.
Some immunocompromised patients:
- The studies did not include women who are pregnant or breastfeeding.
- Although there are no signals for concern regarding teratogenicity (harm to the baby), data from clinical trials is not available for this group at this time.
- The most recent position of American College of Obstetrics and Gynecology (ACOG) can be found here: ACOG COVID-19 Vaccine Guidance. Statements from Tri-State Perinatology and the Society for Maternal Medicine can be found at the following links:
- Risks associated with the COVID infection in pregnant patients can be found here:
- Tri-State Perinatology at The Women's Hospital maternal fetal experts have provided a video for this topic at length. Watch Now
- Patients receiving immunosuppressive therapy (high dose systemic corticosteroids, some cancer drugs), were also excluded from the study.
- Patients with short-term corticosteroids could be included if it had been >28 days since receipt of these drugs.
- There are no specific safety concerns at this time in immunocompromised patients. There could be concerns related to lower level of efficacy/immune response, but this should be weighed against the fact that patients who are immunocompromised are at higher risk to have a poor outcome from COVID infections themselves.
- The FDA has stated that the vaccine may potentially be less effective in immunocompromised patients, but they did not state any safety concerns among this group.
The federal government and state departments of health have set up guidelines (which have changed several times) for the timeline and prioritization of vaccine distribution. The schedule of these is based upon vaccine availability. This topic will likely remain high-interest for some time in the media, so watch for updates.
It is currently unknown if people who have already had COVID will need to be vaccinated again. There is limited data on how long immunity lasts after an infection. The Indiana Department of Health and many other organizations are currently recommending to wait at least 3 months after being diagnosed with COVID to get the vaccine.
There has not been enough time to evaluate exactly how long antibodies are expected to last, so it is unknown at this time whether this will be an annual vaccination.