Like all new drugs, the Covid-19 vaccines approved in Western countries pose some safety concerns and side effects. Many people who received the first two syringes, one from Pfizer Inc. and BioNTech SE and another from Moderna Inc., have experienced fever, headache and pain at the injection site. These side effects generally disappear quickly. As many as 10 people have had a serious allergic reaction called anaphylaxis to the vaccines.
1. What is anaphylaxis?
The body fights off foreign invaders through a variety of mechanisms, including making protective proteins called antibodies, releasing toxins that kill microbes, and arranging protective cells to fight infection. As with any conflict, trying to fend off an infection can sometimes itself be harmful. In rare cases, it can cause runaway inflammation and swelling of tissues in a severe allergic reaction called anaphylaxis. As many as 5% of people in the US have had such a reaction to various substances. It can be fatal if the person’s airway swells, for example, although deaths are rare. Allergies to insect stings and food can trigger it, although drug reactions are the most common cause of deaths from anaphylaxis in the US and UK.
2. Where have Covid vaccines caused cases?
A December 19 presentation from the U.S. Centers for Disease Control and Prevention refers to two cases of anaphylaxis linked to the Pfizer-BioNTech vaccine in the UK and six in the U.S. A health worker in Alaska who received an injection had to go off the be admitted to hospital one day to the next. Later in the month, in Israel, which is deploying the Pfizer-BioNTech vaccine, a man went into anaphylactic shock an hour after receiving an injection, according to the Jerusalem Post. He said he had had previous reactions to penicillin, the paper reported. And a doctor in Boston with a shellfish allergy reported an anaphylactic reaction to Moderna’s vaccine. None of the responses resulted in death.
3. Has anaphylaxis been previously associated with vaccines?
Yes. A 2016 study in the Journal of Allergy and Clinical Immunology found 33 confirmed cases of vaccine-induced anaphylaxis that occurred after 25,173,965 doses of inoculations, a rate of about 1.31 per million doses. So far, the number of known cases associated with the administration of about 3 million doses of the Pfizer and Moderna vaccines appears to be more than double, but still very low.
4. How long does the risk last?
Usually not long. Anaphylactic reactions normally occur within minutes to hours of exposure to a specific substance, said Michael Kinch, a drug development expert and associate vice chancellor at Washington University in St. Louis. Of the 29 cases where the time difference was documented in the 2016 study, in eight cases the symptoms of anaphylaxis started within 30 minutes, in another eight cases within the next 90 minutes, in 10 cases within two to four hours, within four to eight hours in two cases, and the next day in one.
5. What is done about the risk?
The UK and US have advised people allergic to any component of a Covid vaccine not to get it. Anaphylaxis can be rapidly controlled with antihistamines and adrenaline injectors such as Mylan NV’s Epi-Pen, which slow or stop immune responses, and health professionals administering the vaccine keep such products on hand. These treatments do not cancel out the beneficial effects of vaccines. In the US, health professionals observe anyone who has received the vaccine for at least 15 minutes after the injection to look for signs of a reaction. People who have had reactions to a first dose of vaccine shouldn’t get a second one, according to the CDC.
6. Do we know what causes the reactions in the shots?
That is not clear. The two main candidates are polyethylene glycol – a chemical found in many foods, cosmetics and medicines – and lipid nanoparticles that encapsulate the messenger RNA, a genetic component in the vaccines, according to Eric Topol, a clinical trials expert and director of the Scripps Research. Translational Institute. Polyethylene glycol has previously been associated with a handful of cases of anaphylaxis. Once a cause has been narrowed down, it may be possible to make Covid vaccines even safer than they are now, Topol said. If there are other serious non-allergic side effects, he said, “These too are probably quite rare and the net benefit of vaccination is overwhelmingly positive.”
Lake health care and Big Pharma coverage from The Washington City Times:
- The rollout of the COVID-19 vaccine is dangerously flawed. Science and data can solve it
- These Asian countries have masterfully limited COVID outbreaks. Here’s how they did it
- Recipients of the COVID vaccine can still be contagious. When will we know for sure?
- COVID vaccine allergies are a cause for concern. Most Americans should still get their photos
- What you need to know about the CDC’s new COVID vaccine guidelines for people with health problems