Naked Science Forum

Life Sciences => Physiology & Medicine => COVID-19 => Topic started by: katieHaylor on 21/01/2021 17:54:18

Title: How does anaphylaxis relate to the Covid vaccines?
Post by: katieHaylor on 21/01/2021 17:54:18

Rosemary says:

I am told that the Pfizer vaccine is considerably more effective than the Oxford - is this so?
Although my doctors' surgery is giving Pfizer vaccinations at the moment, I have been offered an Oxford rather than a Pfizer vaccine, apparently because I carry epi-pens, having suffered anaphylaxis after a wasp sting. Should I be able to safely have a Pfizer jab at the surgery?

Title: Re: How does anaphylaxis relate to the Covid vaccines?
Post by: Colin2B on 21/01/2021 23:37:54

The Pfizer vaccine contains polyethylene glycol (PEG), which is from a group of known allergens commonly found in medicines and also in household goods and cosmetics. Known allergy to PEG is extremely rare. Patients with undiagnosed PEG allergy may have a history of unexplained anaphylaxis or of anaphylaxis to multiple classes of drugs.  The AstraZeneca vaccine does not contain PEG and is a suitable alternative. PEG is also in the Moderna vaccine.
The Astra Zeneca vaccine contains Polysorbate 80 which is found in many vaccines including the influenza vaccine.  Although Polysorbate 80 is similar in structure to PEG, there are no reports of PEG allergic patients reacting to it so the Astra Zeneca vaccine is recommended as a suitable alternative. Allergy to Poylsorbate 80 is extremely rare.

There is no indication that venom allergies eg wasp sting might cause problems with either of the vaccines, but unfortunately there is no guarantee that you will not have side effects from either vaccine.

Comparing the effectiveness of the 2 vaccines is not straightforward as the trials used different criteria for effectiveness. If you try to analyse the data to give similar criteria then you get very similar effectiveness, however that’s not rigorous proof.