Side Effects and Safety Monitoring
Are there any safety concerns with the new technologies (mRNA and nanotechnology) being used in the development of the Pfizer-BioNTech and Moderna COVID-19 vaccines?
There are no known additional risks of mRNA vaccines or lipid nanoparticles. Live attenuated viral vaccines, such as measles vaccine, induce an immune response that is similar to natural infection. mRNA vaccines, on the other hand, simply give the body instructions to produce one very specific part of a virus – in this case the so-called spike protein – to then induce an immune response. Because mRNA is broken down very quickly in the human body, to do its work it needs to be able to get into our cells, and so it is wrapped in a lipid nanoparticle. Once it gets into the cells to deliver the instructions, the mRNA breaks down very quickly. It does not get into the nucleus of the cell, or into our genes. Since the new mRNA vaccines have been administered, their safety profiles are reassuring.
Since April 2021, rare cases of myocarditis and pericarditis have been reported in adolescents and young adults (under 30 years of age) following receipt of mRNA vaccines – most often following the 2nd dose. COVID-19 vaccination reduces patients’ risk of myocarditis caused by getting infected with SARS-CoV-2 and developing COVID-19 disease. Studies have shown that risk of myocarditis was up to 6 times higher post SARS-CoV-2 infection than post-mRNA vaccines. Post-vaccine myocarditis is milder, requiring shorter hospital stays (1-2 days) vs. myocarditis caused by SARS-CoV-2 infection which has been more severe requiring a hospital stay of 5 days on average. Pediatricians should consider myocarditis and pericarditis in adolescents or young adults with acute chest pain, shortness of breath, or palpitations and report any suspected cases post COVID-19 vaccination to VAERS. History of myocarditis of pericarditis after a dose of an mRNA vaccine is also listed as a precaution for future doses. CDC continues to monitor the situation and has created guidance for health care providers
Clinical Considerations: Myocarditis after mRNA COVID-19 Vaccines | CDC
What side effects are noted to date with COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna)?
The side effects have been similar to other routine vaccines- sore arm, redness, fatigue, fever, chills, headache, myalgia, and arthralgia. The side effects are temporary and mostly mild or moderate. Side effects may be worse after the second dose in some individuals. Anaphylaxis has been observed following receipt of COVID-19 mRNA vaccines but this has been rare. Extremely rare cases of myocarditis or pericarditis have been reported – most often in males between 12-39 years of age – and most often following the 2nd dose. Additional information on common side effects and rare adverse reactions can be found here:
Possible Side Effects After Getting a COVID-19 Vaccine | CDC
Selected Adverse Events Reported after COVID-19 Vaccination | CDC
What side effects are noted to date with the Janssen COVID-19 viral vector vaccine? Are there any contraindications?
Common side effects post vaccination are pain, redness, and swelling in the arm where you received the shot, as well as, tiredness, headache, muscle pain, chills, fever, and nausea within the first few days.
CDC considers the following to be a contraindication to receiving Janssen COVID-19: Severe allergic reaction or immediate allergic reaction of any severity to a previous dose or component of Janssen COVID-19 vaccine. Precautions should be taken for individuals with a history of immediate allergic reaction to another vaccine or injectable therapy and those with moderate or severe acute illness.
Additionally, in December 2021, the FDA revised the EUA Fact Sheet for Janssen COVID-19 vaccine to include: (1) a contraindication for individuals with a history of thrombosis with thrombocytopenia following the Janssen COVID-19 vaccine or any other adenovirus-vectored COVID-19 vaccines; and (2) a warning and precaution for Thrombosis with Thrombocytopenia Syndrome (TTS) as cases of TTS following administration have been reported in males and females 18 years of age and older, with the highest rate in females aged 30-49 years. Providers should maintain a high level of suspicion for symptoms that might represent serious thrombotic events or thrombocytopenia in patients who have recently received the Janssen COVID-19 vaccine. See CDC Health Alert Network for additional information.
On July 12, 2021, the FDA announced it is adding a warning label to the Janssen COVID-19 vaccine, due to an increased risk of a rare neurological syndrome called Guillain-Barré syndrome (GBS). The new warning label is based on preliminary data, after about 100 reports of GBS were detected in the Vaccine Adverse Event Reporting System, out of more than 12.8 million administered doses of the Janssen vaccine administered. Each year an estimated 3,000 to 6,000 people develop GBS in the US from various causes. Most people fully recover from the disorder.
The CDC has recommended COVID-19 vaccines with a preference for people to receive an mRNA vaccine (Pfizer-BioNTech and Moderna) or the protein subunit vaccine (Novavax). Janssen (viral vector) vaccine is available for individuals who are unable or unwilling to receive another vaccine and are aware of the safety profile.
What side effects are noted to date with the Novavax protein subunit vaccine? Are there any contraindications ?
Side effects similar to other vaccines, (such as fever, chills, tiredness, and headache) are more common after the second dose of the vaccine. Severe allergic reactions to vaccines are rare but can happen. Cases of myocarditis and pericarditis have been reported in people who received Novavax COVID-19 vaccine.
Novavax COVID-19 Vaccine should not be given to individuals with a known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the Novavax COVID-19 Vaccine, Adjuvanted.
Are there any contraindications to receiving COVID-19 mRNA vaccines from Pfizer-BioNTech and Moderna?
CDC considers the following to be a contraindication to vaccination with both Pfizer- BioNTech and Moderna COVID-19 vaccines: Severe allergic reaction (eg., anaphylaxis) after a previous dose of an mRNA COVID-19 vaccine or any of its components, immediate allergic reaction of any severity to a previous dose of an mRNA COVID-19 vaccine or any of its components (including polyethylene glycol [PEG]), and immediate allergic reaction of any severity to polysorbate (due to potential cross-reactive hypersensitivity with the vaccine ingredient PEG)*
In persons who report a history of anaphylaxis to another vaccine (i.e., any other vaccine besides the Pfizer-BioNTech and Moderna COVID-19 vaccine) or injectable therapy, a risk assessment should be conducted to determine type of reaction and certainty of information. A small number of vaccine recipients have experienced anaphylaxis following receipt of the Pfizer vaccine. Consider observing people with the following medical histories for 30 minutes after COVID-19 vaccination to monitor for allergic reactions:
Patients who experience anaphylaxis following the first dose of COVID-19 vaccine should be counseled not to receive the second dose and referred to an allergist-immunologist for appropriate follow up.
Do we need to worry about an increase in MIS-C in kids receiving COVID-19 vaccine?
To date, MIS-C has not occurred following receipt of COVID-19 vaccine without SARS-CoV-2 infection. In fact, COVID-19 vaccine offers protection against MIS-C, as a recent study demonstrated that receipt of 2 doses of Pfizer-BioNTech COVID-19 vaccine is highly effective in preventing MIS-C in persons 12-18 years of age.
What is the safety testing that has been done on COVID-19 vaccines? How do we know it is safe long-term?
The safety follow-up for COVID-19 vaccines is essentially the same that it is for all vaccine trials. All vaccines are determined to be safe and effective before they are authorized or licensed.
Pediatric vaccine studies involve very close follow up and tracking of patient’s health status and medical care post vaccination (eg. monitoring side effects, medical visits, use of new medications or changes to previous medications, and other interactions post vaccination). All reported medical events are recorded and reviewed by the study team, sponsor, an independent safety monitoring board, an ethics committee, and the FDA. Children in these studies are often followed for one to two years post vaccination and their health status is monitored for vaccine safety.
Even after authorization or licensure, safety data are collected through Vaccine Adverse Event Reporting System (VAERS), Vaccine Safety Datalink (VSD), pharmacovigilance, and, for COVID-19 vaccines, through a system called V-SAFE. These programs collect information on an even larger number of persons who get vaccinated than can be collected during clinical studies.
Safety data beyond 2 years, is captured through studies performed post licensure. No licensed vaccines have been found to have an unexpected long-term safety problem, that was found only years or decades after introduction.
What vaccine safety surveillance programs are in place?
All COVID-19 vaccines approved and/or granted Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) and vaccines on the Recommended Child and Adolescent Immunization Schedule, including co-administered vaccines are monitored through robust FDA and CDC systems that monitor vaccine safety in the United States. This vaccine safety system includes the Vaccine Adverse Event Reporting System (VAERS), Vaccine Safety Data Link (VSD), Clinical Immunization Safety Assessment (CISA), and V-SAFE, a new smartphone-based system added to the safety monitoring system specifically to monitor for side effects of the COVID-19 vaccines. These systems have proven that they work in picking up a safety signal for an extraordinarily rare complication with the Janssen COVID-19 vaccine. VAERS and VSD are specifically designed to monitor safety signals from simultaneous administration of multiple vaccines (ie co-administration). Pediatricians should share information with patients on VAERS and encourage registration in the V-SAFE program during the vaccination visit.
Ensuring COVID-19 Vaccine Safety in the US | CDC
V-safe After Vaccination Health Checker | CDC