The Pfizer-BioNTech COVID-19 vaccine may sometimes cause no side effects or mild-to-moderate side effects, which can be fairly common post-vaccination. This Snapshot feature further addresses concerns around allergic reactions and false claims regarding risks to pregnancy and fertility.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.
Sex and gender exist on spectrums. This article will use the terms “male” and “female” to refer to a person’s sex assigned at birth.
The Pfizer-BioNTech COVID-19 vaccine, named BNT162b2, and known as Comirnaty in the European Union, is a two-dose mRNA vaccine developed by two pharmaceutical industry companies: Pfizer in the United States and BioNTech in Germany.
In December 2020, the
This mRNA vaccine works by providing the body with a set of instructions for creating the spike protein found on the surface of the SARS-CoV-2 virus. The presence of the protein antigen in the body triggers the immune system to produce antibodies, which prepares the body to fight against future infection by the virus itself.
However, the vaccine does not contain the virus and cannot cause infection. Additionally, the mRNA in the vaccine does not have the ability to alter DNA inside cells, as it is a transient molecule and does not enter the nucleus where the DNA is stored.
Although mRNA vaccines have been studied for many years, they have never before been approved for human use against disease. As a result, members of the public have raised concerns regarding potential unknown side effects.
According to the
Individuals have also reported side effects at the injection site, including arm pain, redness, and swelling.
These side effects are often signs that the vaccine is working, inducing a protective response from the immune system.
Many individuals who received both doses of the vaccine have reported that symptoms are more prominent after the second dose. However, in most cases, these have been mild to moderate and last no more than a few days.
- difficulty breathing
- swelling of face and throat
- rapid heartbeat
An ingredient found in mRNA vaccines that is of particular concern regarding allergic reactions is a chemical called polyethylene glycol (PEG).
PEG is commonly found in laxatives used to treat constipation. In the vaccine, PEG functions to coat the mRNA molecule and support its entrance into cells. PEG has not often been a component of previous vaccines, so there is limited information on its allergic effects.
Those with a history of severe or immediate allergy to PEG or other ingredients in mRNA vaccines are advised not to receive this type of COVID-19 vaccine.
Concerns regarding the
The source — since removed from the web — claimed that the antibodies produced by the body in response to the vaccine, which targets the SARS-CoV-2 virus’ spike protein, could also target syncytin-1 and cause infertility.
Scientists have demonstrated this claim to be inaccurate. Firstly, immunologists have shown no significant similarity between the genetic information of these two proteins, while blood plasma from COVID-19 patients does not react with syncytin-1.
Secondly, if this claim were true, it would mean that natural SARS-CoV-2 infection would likely cause a higher rate of miscarriage. This has not been seen in studies examining the effects of COVID-19 — female participants with the disease did not display a higher risk of early pregnancy loss.
Additionally, the vaccine’s clinical trials included 11 female participants in the vaccinated group who became pregnant during the trial, compared to a similar number of 12 female participants in the control group.
While there is not yet long-term evidence regarding this claim, animal studies have also not reflected any evidence of fertility loss due to the vaccine.
Pfizer and BioNTech are also conducting clinical trials in pregnant people to observe the vaccine’s effects in those who are pregnant as well as their infants.
In the patient fact sheet, the FDA notes that, for people who experienced myocarditis or pericarditis after their vaccine, “symptoms began within a few days following receipt of the second dose.” However, it also adds that “[t]he chance of having this occur is very low.”
The FDA advises people to seek medical attention immediately should they experience chest pain, shortness of breath, or “feelings of having a fast-beating, fluttering, or pounding heart” after receiving the Pfizer-BioNTech vaccine.
The CDC further
Regulatory agencies are keeping a close eye on the safety of COVID-19 vaccines. Up to this point, there have not been any risk indications that require a pause in distribution for the Pfizer-BioNTech vaccine.
Additionally, health experts note that while some people may experience minor or moderate side effects after vaccination, these typically go away after a few days.