Janssen, AstraZeneca, Pfizer, Moderna … This is how COVID-19 vaccines are: origin, age and effectiveness


Publication: Thursday, April 15, 2021 6:01 AM

The EMA has so far approved four coronavirus vaccines: Pfizer, Moderna, AstraZeneca and Janssen. But, four months later, since Spain started to vaccinate them, what do we know about them, how effective each one is, in which groups are they administered? We review all the information on the main health weapon against the pandemic.

Pfizer / BioNTech

The vaccine developed by Pfizer is, according to the European Medicines Agency (EMA), 95% effective in its ability to reduce the number of symptomatic cases of COVID-19 in people who have received the vaccine in previous studies.

In Spain, this injection is mainly used in seven of the groups foreseen by the government in the vaccination plan of the Interterritorial Health Council. In this way, all people over the age of 70 who belong to one of these groups receive two doses of this vaccine:

– The residents and health personnel of these centers. (Vaccination completed).

– Front-line health personnel. (Vaccination completed).

– Primary care workers, other health and social health groups, dentists and dental hygienists.

– People considered to be large dependents and their caregivers.

– People aged 80 or over.

– People aged 70 to 79 (approximately 20% received this injection).

As reported by the Ministry of Health, the contract signed between the EU and the pharmaceutical company stipulates that some 52 million doses arrive in our country. Despite everything, as announced on Wednesday by the President of the European Commission, Ursula Von Der Leyen, after the recent shutdowns, the pharmaceutical consortium of Pfizer and BionTech will advance the delivery of 50 million doses of its vaccine in the second quarter, in 25% increase. supply. As with the rest of the RNA injections, it is necessary to use it twice.

Currently, CCAAs have increased a noticeable increase in vaccine arrivals, at a rate during this month of April of 1.2 million weekly doses, while the total for the month is 4.8 million vaccines.

Regarding side effects, the Spanish Medicines Agency (AEMPS) has identified pyrexia (fever), anaphylaxis (a type of allergic reaction), malaise, nausea or chills as the main consequences, as indicated in its pharmacovigilance document against COVID-19. Here are the most common effects:


According to the EMA, this vaccine is 94.1% effective in its ability to reduce the number of symptomatic cases of COVID-19 in people who have received the vaccine. The test was performed on approximately 28,000 people between the ages of 18 and 94 who showed no signs of previous infection.

In Spain this injection is used in the same groups as those previously mentioned with Pfizer; that is, all people in priority groups who are over 70, as well as front-line professionals and health workers who have already benefited from it.

According to the Ministry of Health, the contract signed between the EU and this company certifies that around 33 million doses of the injection will reach Spain. Along with this, as with Pfizer, this injection requires two doses to boost immunity.

On the other hand, the harmful effects that result from the injection of Moderna are very similar to those of Pfizer, also in terms of percentages: while the first has 42% of people injected with fever, in the second the figure reaches 39%.


The vaccine developed by AstraZeneca has, according to EMA studies, an effectiveness of 59.5% in its ability to reduce the number of symptomatic cases of COVID-19 in people who have received the vaccine. This research combined four clinical trials, conducted in the UK, Brazil and South Africa, which showed the COVID-19 AstraZeneca vaccine “to be safe and effective in preventing COVID-19 in people aged 18 and over. and more, ”explains the entity. .

However, the EMA also argued that “there are still not enough results in participants over 55” to provide a figure that attests to its effectiveness in this group, although they also state that , at the same time, “there is information on the safety of the vaccine” in this population.

In Spain, after the company had various problems with the EU while supplying its vaccines, the signed contract says that around 31 million doses of AstraZeneca will arrive in our country. It also requires two doses to use, although it is a different type of vaccine (while the previous two are mRNA type, it is an adenovirus vector).

Until a few days ago, this vaccine was used in:

– Health and social health staff not previously vaccinated, physiotherapists and occupational therapists, pharmacy office staff, etc.

– The rest of the professionals who work in the health fields, as well as the rest of the health professions: veterinarians, nutritionists, etc.

– Security forces and corps, emergencies and armed forces.

– Teachers and staff of early childhood education and special educational needs.

– Teachers and staff of primary and secondary education.

As a result of recent health updates, it is now only given to people aged 60 to 69, while a decision has yet to be made regarding people in these groups under 60. who have already received the vaccine.

In this sense, as reported by the Minister of Health, Carolina Darias, two options are being considered. On the one hand, leave people who have already received this first dose as is, without a second puncture (according to health data, they would already benefit from around 70% immunity without completing the process). And, on the other hand, the possibility of mixing two different vaccines is on the table, although the safety of this decision should first be confirmed, because the scientific community has not yet approved it.

When it comes to side effects, the AstraZeneca vaccine has been one of the hardest hit by recent reports. However, despite the fact that the EMA admitted a “possible relationship” between the recorded thrombi and the injection, the data shows that this is a more than effective and safe vaccine – to get an idea , there is a greater risk of suffering from one of these thrombi when boarding an airplane than when receiving the vaccine.


Janssen’s vaccine is the fourth approved by the European Medicines Agency (EMA), behind the already known antidotes of Pfizer, Moderna and AstraZeneca, although its arrival in Spain is still pending after the delay announced by the pharmaceutical company which developed it.

This vaccine was developed by the Belgian pharmaceutical company Janssen, itself a subsidiary of a much larger company: the American giant Johnson and Johnson. In this case, unlike other injections, we are talking about a viral vector vaccine which, as the US Center for Disease Control (CDC) states, “contains a modified version of another virus (the vector) for their. give important instructions to our cells. “In other words, it is a more” classic “and recognizable type of injection, which finds its main virtue in the economy of doses.

According to the EMA, it is a vaccine with “solid data” which meets “the criteria of efficacy, safety and quality”. A total of 44,000 people participated in the trials, although divided into two groups: on the one hand, 22,000 of them received the antidote, while the remaining 50% were given a placebo – a type of substance. which lacks healing capacity. useful to see the reaction of the population in this type of experiment.

For their part, the clinical results are clear-sighted: two weeks after the injection, there was a 67% reduction in the number of symptomatic cases of COVID-19 (there were only 116 cases left out of 19,630 people). In other words, this same percentage, according to the EMA, illustrates its effectiveness: 67%. This means that the vaccine was 67% effective.

However, according to the technical guide of the Interritorial Health Council, its ability to vaccinate is even greater: in the group of 65 years and over, the effectiveness reaches 82.4%, while in the group of 75 years and over it even amounts to 100%, so, according to this entity, its total effectiveness would increase to 76.7% at 28 days of vaccination, against 14 days measured by the EMA.

As indicated by the Minister of Health, this injection will first be vaccinated in a group: in that of people aged 70 to 79 years. However, like any type of vaccine of this type, people who benefit from this injection are likely to experience mild side effects.

Thus, according to Health, the most frequent consequences are: fever, malaise, muscle aches and fatigue. The EMA, in this line, insists that these “are usually mild or moderate and go away a few days after vaccination”. It also adds other types of effects to the list, such as injection site pain, headache, fatigue, muscle pain, and nausea.

Other vaccines

It should be taken into account that the vaccines mentioned are those which have already received approval from the European Medicines Agency, but Spain also plans to integrate into its arsenal other injections which, once the corresponding controls past, will be used to continue the fight against the coronavirus.

In this sense, a contract is being negotiated with the company Novavax, whose vaccine is also under review, as well as another with the French company Sanofi. However, no date has been specified for its review and application, which should be in 2021, nor the number of doses that would reach Spain. Even so, the contract is already signed.

Added to this is one of the great novelties of recent weeks: the Russian vaccine, Sputnik V, is already under review by the drug agency. This fact only means one thing: as happened with previous injections, like those from Pfizer, Moderna or AstraZeneca, the entity will review in real time, as the data is released, the effectiveness and quality of this antidote against the coronavirus. Despite everything, unlike what is happening with the others, Spain has not (yet) signed any agreement with the injection developed at the Russian National Epidemiology Center.

Here is the distribution of vaccines that are or will be used in Spain:

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