COVID-19 vaccines: secrets and strange facts about COVID-19 vaccines

COVID-19 vaccines: COVID-19 is an infectious disease caused by a coronavirus, SARS-CoV-2, which primarily affects the respiratory tract.

Transmission occurs through close contact with a person who carries the virus (mainly through direct contact or through respiratory secretions emitted into the air when coughing, sneezing or talking. ).

This disease appeared in China at the end of 2019 and the virus was identified in early January 2020.


The search for a vaccine against COVID-19 started in March 2020. The work of laboratories has been facilitated and faster than in the past thanks to the development of vaccines against other coronaviruses, SARS-CoV and MERS- CoV, and by the introduction of new manufacturing techniques.

Today, more than 200 candidate vaccines are in development or testing.

What is a vaccine?

A vaccine prepares your body to fight off a particular infection, virus, or disease. Vaccines contain inactive or weakened parts of the body that cause disease, or a « blueprint » that will trigger the same reaction.


This prompts the immune system to recognize the invader if it comes and to produce antibodies to learn how to fight it.

COVID-19 vaccines

The aim of the vaccination is to ensure the direct protection of the vaccinated people against the severe course of the disease and to reduce or prevent hospitalizations and deaths.

Pfizer / BioNTech vaccine

For Pfizer / BioNtech’s Comirnaty vaccine, the EMA granted its authorization for use in Europe on December 21, 2020.

Clinical trials were carried out on 43,000 people aged 16 to 85 who received half the vaccine – 2 injections – and half the placebo.

The effectiveness in preventing cases of COVID-19 was 95%. This very high efficacy was comparable regardless of age, sex, build, ethnic group, and the presence of risk factors.

AstraZeneca vaccine

For the COVID-19 vaccine Vaccine AstraZeneca from the Astra-Zeneca laboratory, the EMA gave its authorization for use in Europe on January 29, 2021.

Clinical trials were carried out on 16,437 people aged 18 and over who received half the vaccine -2 injections- and half the placebo.

The effectiveness in preventing cases of COVID-19 was 62%. The prolongation of the interval between 2 doses up to 12 weeks is accompanied by an increase in vaccine efficacy. « 

Moderna vaccine

For the Moderna COVID-19 vaccine; Vaccine Moderna, the EMA gave its authorization for use in Europe on January 6, 2021.

The clinical trials were carried out on 30,350 people aged 18 and over who received half the vaccine -2 injections- and half the placebo. The effectiveness in preventing cases of COVID-19 was 94%. This efficiency is very high.

Known side effects of COVID-19 vaccines

In the days following vaccination, some side effects may occur and in most cases go away within a few days.

Pfizer / BioNTech vaccine

Based on observations made on 8,000 people over the age of 55, during phase 3 clinical trials:

  • In about 7 out of 10 people, the sting causes mild to moderate pain at the time. About 1 in 20 people also develop a transient redness and/or itching.
  • Feelings of fatigue may also occur (in half of the people vaccinated), headaches (in around 2 in 5 people), shivering, muscle or joint pain (in around 1 in 5 people). About 1 in 10 people develop a transient fever, and 1 in 12 people develop diarrhea.

source.

Moderna vaccine

Based on observations made on 15,000 people who received the vaccine during phase 3 clinical trials:

  • In about 9 out of 10 people, the sting causes mild to moderate pain at the time. About 2 in 20 people also develop transient redness and/or itching.
  • Feelings of fatigue may also occur (in two-thirds of people vaccinated), headaches (in around 3 in 5 people), shivering, muscle or joint pain (in around 2 in 5 people). About 2 in 10 people develop transient fever.

source.

AstraZeneca vaccine (source)

Very Common (may affect more than 1 in 10 people)

  • tenderness, pain, warmth, redness, itching, swelling, or bruising where the injection is given
  • generally feeling unwell
  • feeling tired (fatigue)
  • chills or feeling feverish
  • headache
  • feeling sick (nausea)
  • joint pain or muscle ache

Common (may affect up to 1 in 10 people)

  • a lump at the injection site
  • fever
  • being sick (vomiting)
  • flu-like symptoms, such as high temperature, sore throat, runny nose, cough, and chills

Uncommon (may affect up to 1 in 100 people)

  • feeling dizzy
  • decreased appetite
  • abdominal pain
  • enlarged lymph nodes
  • excessive sweating, itchy skin, or rash

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