The Ministry of Health has published this Wednesday, March 23, the 14th Pharmacovigilance Report about COVID-19 vaccines. The report aims to communicate the adverse reactions that are producing the vaccines against the coronavirus. This issue emphasizes the effects that have caused the third dosesthat is, the booster vaccines from Pfizer and Moderna, also known as Comirnaty and Spikevax, respectively.
According data from the Ministry of Health, 92.3% of people over 12 years of age have already received the full guideline against COVID-19. What’s more, A total of 24,312,467 additional doses have already been applied. In Spain, only those that use messenger RNA technology, that is, Pfizer and Moderna, are injected as third doses.
Of the total number of people vaccinated, 51% are women. Regarding the distribution by age groups, 67% corresponds to people between 18 and 65 years old21% to people over 65 years of age, 7% to people between 12 and 17 years of age and 5% to children under 12 years of age.
Adverse effects of third doses
During this period it has been possible to identify 1,208 notifications of adverse events after the administration of the third dose, of them 37% corresponded to the administration of Pfizer and 63% to Moderna; most have occurred in women (69%) and in people between the ages of 18 and 65 (87%)
Pfizer Side Effects
The report collects the ten most reported side effectsas well as its percentage with respect to the total number of notifications identified for the third dose.
The ten most common adverse effects of the third dose of Pfizer
| Reaction (PT) | Number of cases | Percentage |
| lymphadenopathy | 94 | 21% |
| Pyrexia | 89 | 20% |
| Headache | 44 | 10% |
| Myalgia | 34 | 8% |
| Discomfort | 32 | 7% |
| Fatigue | 25 | 6% |
| Vaccination site pain | 19 | 4% |
| Shaking chills | 18 | 4% |
| Arthralgia | 15 | 3% |
| Axillary pain | 15 | 3% |
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Of the total of 35,360 registered notifications, 443 occurred in people who received the third dose. The most common adverse effect was lymphadenopathy, that is, swollen lymph nodes (21% of those who had one experienced lymphadenopathy). The pyrexia or fever was the second most recorded effect (20%), followed by headache or headache (10%).
Side Effects of Moderna
From Moderna there have been 13,302 notifications of side effects, of which 762 occurred in people who received a third dose. The following table also shows the ten most common symptoms together with their percentage with respect to the total number of notifications identified for the third dose.
The ten most common adverse effects of the third dose of Moderna
| Reaction (PT) | Number of cases | Percentage |
| Pyrexia | 258 | 34% |
| Headache | 136 | 18% |
| lymphadenopathy | 122 | 16% |
| Myalgia | 95 | 12% |
| Discomfort | 68 | 9% |
| Vaccination site pain | 67 | 9% |
| Sickness | 61 | 8% |
| Fatigue | 58 | 8% |
| Arthralgia | 51 | 7% |
| Shaking chills | 49 | 6% |
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In the case of Moderna, the pyrexia (34%) is the most recurrent adverse effect among patients who have received the third dose, followed by the headache (18%) and for the lymphadenopathywhich in this case falls to 10%.
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