Moderna and Pfizer mRNA Vaccine, from What’s in it to Side Effects

Steve Puts
3 min read

What does an mRNA vaccine contain?
The active ingredient is mRNA which is contained in liposomes (fat vesicles). The genetic material (mRNA) will transcribe part of the spike protein of the virus to trigger an immune response. It provides protection after about one or two weeks. In addition, the vaccine contains, among other things, lipids such as polyethylene glycol (PEG), cholesterol, water, salts, and sucrose.

Currently, in most countries both the Moderna and Pfizer/Biontech vaccines are available. We will take a look at both. How effective are they and what are the side effects?

THE PFIZER / BIONTECH VACCINE

What are possible side effects?
More than half: pain and stiffness around the injection site, fatigue and headache. In a quarter or more: muscle pain, joint pain or chills. One in seven can develop a fever. All side effects are mild to moderate and usually disappear after one or a few days.

It is recommended to keep an eye on people for 15 minutes after administration. This is because some people had an allergic reaction after the vaccination. All of them were people with known previous allergies.

Photo: Box with Moderna COVID-19 vaccine vials.

How effective is the vaccine?
In a study on 44,000 people, half of whom received the vaccine and half a placebo, the vaccine was found to protect 95 percent of the participants against coronavirus. It seems to work just as well in the elderly. No severe covid was seen in the vaccinated group. It is believed that after a single dose one is about 50 percent protected. The entire vaccination consists of two injections.

Who is the vaccine for?
For anyone over the age of 16. The vaccine can also be useful for people who have already had a coronavirus infection: it can strengthen any immunity that has developed during the infection.

THE MODERNA VACCINE

What are possible side effects?
In more than half of the people: pain and stiffness around the injection site, fatigue, muscle pain and headache. In a quarter or more of the people: joint pain, chills or nausea. One in seven can develop a fever. Rarer are swollen axillary glands (about 2 percent) and high fever (2 to 3 percent).

The side effects are usually mild to moderate, and more noticeable after the second dose and in people under 65. About one in ten is affected by the side effects to the extent that they take a painkiller or call in sick. Generally, the complaints disappear after one or a few days. Nevertheless, one in ten still has a few, usually mild, complaints after a week.

How effective is the vaccine?
In a study of about 30,000 people, half of whom received the vaccine and half a placebo, the vaccine was shown to protect 70 percent after one dose and 94 percent of the vaccinated group against coronavirus after the second shot. People over 65 were also protected. No severe COVID-19 was seen in the vaccinated group.

Who is the vaccine for?

For everyone over the age of 18. The vaccine can also be useful for people who have already had a coronavirus infection: it can strengthen any immunity that has developed during the infection. Pregnant women or people with a severely weakened immune system should consult their doctor to assess the risks versus the benefits.

What possible drawbacks and what unresolved questions are there?
It is still unclear exactly how long the protection generated by the vaccine will last. There were also very few pregnant women among the test subjects. It is unknown whether the vaccine stops the virus: some people who received the vaccine may still be able to pass on a future COVID-19 infection. When infected with coronavirus after being vaccinated, the disease is very mild if at all noticeable.

Are there any other rare side effects?
It is conceivable that there are side effects that are so rare that they have not yet been noticed in the trials on tens of thousands of people. Extra attention will be paid to “Bell’s palsy”, a usually temporary condition in which the corner of the mouth and eyelid hang down on one side of the face. The trials identified four cases of paralysis in the vaccinated group. But that falls within the margins of chance, if you monitor the health of tens of thousands of people for months.

To know more about how mRNA vaccines work, check out our article on Nucleic Acid Based Vaccines

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