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  • Report Moderna's vaccine has the highest rate of adverse effects and AstraZeneca, the lowest

The Spanish Agency for Medicines and Health Products (Aemps) has published the Fourth Pharmacovigilance Report on vaccines against covid-19, in which it collects the relevant information of those employed at the moment in Spain gathered since the publication of the previous report from the past month of March.

The agency's data reveal that,

until March 21, 2021, 6,125,119 doses

of vaccines against Covid-19

have been administered in Spain

, corresponding to

4,136,963 people

, since 48% received the guideline complete with two doses.

79% of the administered doses corresponded to Comirnaty (Pfizer / BioNtech), 16% to Vaxzevria

(AstraZeneca) and 5% to COVID-19 Vaccine Moderna (Moderna).

Of the total number of people vaccinated,

67% are women.

Regarding the distribution by age groups,

61% correspond to people between 18 and 65 years old

, and 39% to people over 65 years old.

So far,

11,182 notifications of adverse events

have been received

(183 notifications per 100,000 doses administered), among which the most frequent continue to be

general disorders

(fever, pain in the vaccination area), of

the central nervous system

(headache, dizziness) and the

musculoskeletal system

(myalgia and arthralgia).

Most of the notifications correspond to people between 18 and 65 years of age (93%) and mostly to women (82%).

Three cases involving short-term, non-serious events have been reported in infants whose mothers had received the Pfizer or Moderna vaccines, specifically diarrhea, vomiting, and irritability.

According to the available data, the Aemps reflects in this latest document that the

effects observed after the Comirnaty vaccine, from Pfizer / BioNtech

(8,447 adverse effects reported between December 27, 2020 and March 21, 2021), may be inflammation in the end of administration of the vaccine, more extensive than the injection site.

Also in the case of this vaccine, the possible appearance of inflammation in areas of the face in which filler injections had been previously applied under the skin (for example, of hyaluronic acid) are being studied.

The AstraZeneca case, in depth

In the case of

Vaxzevria, that of AstraZeneca

(1,792 cases of adverse effects reported in the same period as the previous one), the agency recalls

that its administration is not considered to "produce an increased global risk of thrombotic events

, although" very rarely There have been cases of cerebral venous sinus thrombosis that may be accompanied by low levels of platelets, which are currently under investigation, in line with the official communication of the European agency EMA this week supporting the continuity of vaccination with Vaxzevria.

Aemps recalls that, since the authorization of Vaxzevria by the EMA on February 1 to March 25, more than 10 million doses of this vaccine have been administered in the European Economic Area, and points out that cases of thrombotic events (formation of blood clots in blood vessels) in temporal relation after administration.

In Spain, until March 21, 2021, 5 cases of venous sinus thrombosis had been reported,

two of them with associated thrombocytopenia and one with a fatal outcome, having administered 985,528 doses of this vaccine.

The evaluation of this signal is ongoing, but the preliminary analysis of the EMA Pharmacovigilance Committee (PRAC) has concluded that

no quality problems have been identified with specific batches

of the vaccine,

nor have any problems with its manufacture been identified.

It adds that, globally, the number of cases of thrombosis reported after vaccination, in relation to the number of people vaccinated, is

less than the number of these events that occur in the general population,

so it is not considered that the administration of this vaccine is associated with an increased risk of thrombotic events.

However, very rarely thrombus formation can occur in conjunction with thrombocytopenia.

These events include cerebral venous sinus thrombosis.

Reported cases of these very rare venous sinus thrombosis along with low platelet levels, including some fatal cases, occurred within the first 14 days after vaccination, and most of them were in women up to 55 years of age. old.

Unidentified factors

At the moment, it has not been possible to identify specific risk factors such as age, sex or previous history of bleeding disorders, although the causal relationship with the vaccine cannot be ruled out, following the

opinion of experts from different countries in hematology, cardiovascular medicine , infectious diseases, virology, neurology, immunology and epidemiology.

The agency recalls that the Federation of Spanish Scientific Medical Associations (Facme) has prepared a document aimed at health professionals to facilitate the diagnosis and treatment of these very rare onset pictures of venous sinus thrombosis with thrombocytopenia.


For its part,

the Moderna vaccine has produced, in the majority of the 901 cases of adverse events

reported, general disorders such as fever or pain in the vaccination area, followed by disorders of the nervous system and the musculoskeletal system.

The 10 most reported adverse events are as follows:

Pyrexia (fever):

Pfizer (41%), Moderna (50%), AstraZeneca (66%)

Headache (headache):

Pfizer (30%), Moderna (31%), AstraZeneca (44%)

Myalgia (muscle pain)

: Pfizer (22%), Moderna (23%), AstraZeneca (31%)

Pain in the vaccination area:

Pfizer (14%), Moderna (15%), AstraZeneca (13%)


Pfizer (13%), Moderna (10%), AstraZeneca (15%)


Pfizer (9%), Moderna (11%), AstraZeneca (12%)


Pfizer (8%), Moderna (12%), AstraZeneca (19%)

Arthralgia (joint pain):

Pfizer (8%), Moderna (8%), AstraZeneca (9%)


Pfizer (8%), Moderna (8%), AstraZeneca (14%)

Lymphadenopathy (swollen lymph nodes):

Pfizer (7%), Modern (7%)

According to the criteria of The Trust Project

Know more

  • Science and Health

  • Coronavirus

  • Covid 19

  • Infectious diseases

  • Respiratory diseases

  • Vaccines

  • Pharmacology

  • AstraZeneca

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