Is the Pfizer COVID vaccine safe or not?

Do we know if this vaccine is safe yet?

There was always going to be a concern when releasing a brand new type of vaccine ahead of completion of the usual safety trials. The Pfizer vaccine was released following review of the Phase III trials and testing on around 20,000 selected people. The company were evidently concerned themselves and so have managed to get the government to accept all liability in the event that this vaccine proves unsafe. This is a sensible move by Pfizer as vaccines have a bit of a record of not always proving to be the touted panacea. In his article on Bird Flu 'A big flap about a bit of flu', Professor David Mabey reminds us that predictions of a swine flu epidemic drove the American administration to initiate a population - wide vaccination campaign. "Ultimately there was no pandemic – just a lot of people with Guillain-Barre secondary to the vaccine".

Vaccine induced anaphylactic shock

Is the COVID Vaccine safe enough?After only two weeks of vaccinations with the Pfizer COVID-19 vaccine we are already starting to get worrying reports of immediate adverse reactions. The journal Science is reporting that "suspicions grow that nanoparticles in Pfizer’s COVID-19 vaccine" are triggering severe allergy reactions. The problem seems to be caused by anti-freeze (polyethylene glycol or PEG). The article reports that, "PEG has never been used before in an approved vaccine, but it is found in many drugs that have occasionally triggered anaphylaxis—a potentially life-threatening reaction that can cause rashes, a plummeting blood pressure, shortness of breath, and a fast heartbeat".


Ethylene glycol has a number of industrial uses and is often the main constituent of antifreeze. In a major scandal in 1985, Austrian wine producers were caught adulterating their wine with ethylene glycol in order to improve the body of their sweet wines. According to The New York Times, as a consequence of the scandal, millions of litres of wine had to be destroyed by the West German authorities, which had confiscated or otherwise collected the wine. Doing this in an environmentally acceptable way proved to be something of a challenge, because antifreeze was incompatible with sewage treatment plants. 

It seems that there is a risk that politicos are so eager to vaccinate that even relatively recent lessons from history have just not been learned.

In response to the Science article, Pfizer have said, “appropriate medical treatment and supervision should always be readily available” in case a vaccinee develops anaphylaxis.

According to a US Centre for Disease Control (CDC) report, by the 19th of December 112,807 people had received the vaccine, and from these 3,150 had suffered "Health Impact Events". Health Impact Events are defined as, "unable to perform normal daily activities, unable to work, required care from doctor or health care professional".

Of course, anaphylactic shock is only one of the potential safety concerns. However, if an allergic reaction is going to happen it is likely to be within the first 30 minutes and so it is recommended that vaccines remain at the medical centre until they have the all clear.

Earlier this month (December 2020), The Advisory Committee on Immunization Practices’ (ACIP) Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine report on the CDC website included summary statements on efficacy and safety, although the paper stressed that this was early days and published with a view to meeting emergency deadlines. With regard to whether the vaccine will prevent spread amongst asymptomatic people, they said, "No data were available to assess the efficacy for prevention of asymptomatic SARS-CoV-2 infection".

This interim report states: "ACIP determined that COVID-19 is a major public health problem and that use of the Pfizer-BioNTech COVID-19 vaccine is a reasonable and efficient allocation of resources. Whereas there might be uncertainty in how all populations value the vaccine, it was determined that for most populations, the desirable effects outweigh the undesirable effects".

In the meantime the FDA have stepped in to investigate the adverse events  and say, "We’ll be looking at all the data we can from each of these reactions to sort out exactly what happened, and we’ll also be looking to try to understand which component of the vaccine might be helping to produce them”.

It is also understood that Pfizer are facing "critical supply limitations" in their bid to fulfill a 100 million US dose requirement (not yet formerly ratified). However, Pfizer stress that the related manufacturers will sort it out and also expressed support for President Trump invoking the Defense Production Act, if necessary, to compel suppliers to produce the needed components.


Various conditions caused by exaggerated reactions of the immune system (hypersensitivity reactions) to a variety of substances. Full medical glossary
A fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. Full medical glossary
A sudden outbreak of infection that affects a large proportion of a population. Full medical glossary
A viral infection affecting the respiratory system. Full medical glossary
Invasion by organisms that may be harmful, for example bacteria or parasites. Full medical glossary
An element present in haemoglobin in the red cells. Full medical glossary
A microscopic particle of matter that is measured on the nanoscale, usually one that measures less than 100 nanometers. Full medical glossary
An outbreak of infection that affects numerous people in different countries. Full medical glossary
pulmonary embolism Full medical glossary
septic arthritis Full medical glossary
Relating to injury or concern. Full medical glossary
The means of producing immunity by stimulating the formation of antibodies. Full medical glossary