Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 140,000 Danes

25 March 2021

More than 140,000 Danes have been vaccinated with the COVID-19 Vaccine AstraZeneca. As of 23 March 2021, a total of 499 reports of suspected side effects of the COVID-19 Vaccine AstraZeneca have been reviewed. Most of these side effects are known and transient in nature. Eight cases of anaphylaxis have been treated. The drug regulatory authorities are presently investigating reports of the very rare and unusual symptoms of a low level of platelets, blood clots in small and large vessels and bleeding.

In Denmark, more than 140,000 people have been given the COVID-19 vaccine from AstraZeneca. More than 500 of them have received the second vaccine dose.

As at 23 March 2021, the Danish Medicines Agency had received 20,300 reports of suspected side effects to the vaccine, of which 499 have been reviewed. Reports of serious suspected side effects are reviewed first.

The vast majority of reported suspected side effects are mild and moderate. They primarily involve known and transient side effects such as fever, headache, chills and muscle and joint pain.

When a vaccine activates the immune system, many will experience influenza-like symptoms. This is completely normal and a sign that the body’s immune system is reacting to the vaccine. These reactions occur with most vaccine types, and they usually pass within a day or two. However, if the immune system does not react, it does not mean that the vaccine is not working. People simply react differently to being vaccinated.

Allergic reactions

As expected, allergic reactions have also been reported as suspected side effects of the AstraZeneca vaccine.

As with all vaccinations, there is a small risk of rare but severe allergic reactions, including so-called anaphylactic reactions. These reactions are potentially life-threatening if not treated promptly.

The Danish Medicines Agency has assessed 13 reports of severe allergic reactions after vaccination with the COVID-19 Vaccine AstraZeneca. Of these 13 cases, 12 were assessed to be associated with the vaccine, and all were transient. In 9 of the 13 cases, the reactions necessitated treatment and subsequent observation by staff at the vaccination centre or in other settings. In some of these cases, the symptoms required short-term hospitalisation for observation. The Danish Medicines Agency assesses that eight of the cases involved actual anaphylactic reactions (anaphylaxis according to the Brighton classification). All cases of anaphylaxis occurred after the first vaccination.

The Danish Medicines Agency follows and assesses the development of anaphylaxis closely in collaboration with the EMA and other drug regulatory authorities in the EU and globally.

Reports of blood clots

Like other countries, the Danish Medicines Agency has received reports of blood clots after vaccination.

The Danish Medicines Agency has reviewed four reports of blood clots. None of the four reports involves deaths. In all four cases, it is assessed less likely that there is a connection between the vaccine and the symptoms.

Reports of unusual symptoms of blood clots accompanied by a low level of platelets and bleeding

In Denmark and other countries, reports have been submitted on the very rare, yet serious cases of the combination of blood clots and a low level of platelets, in some cases accompanied by bleeding, after vaccination with the AstraZeneca vaccine. In these cases, the blood clots were located at different or unusual places and with excessive coagulation (clotting) or bleeding throughout the body.

Most of these cases occurred within 7-14 days of vaccination. Some cases had a fatal outcome.

The Danish Medicines Agency is currently reviewing two Danish reports describing the aforementioned unusual symptoms with a low level of platelets, blood clots in small and large vessels and bleeding. One of these two cases involves a death. At present, there is no evidence to conclude that these incidents are linked to the vaccine as the review of these cases has not finished yet.

In addition, the Danish Medicines Agency is in the process of reviewing one report of a death after vaccination with the AstraZeneca vaccine. It is still unknown if this is also a case of the unusual symptoms. As the review of this case has not yet finished, it cannot be concluded at present if this incident is linked to the vaccine.

The Danish Medicines Agency, the EMA and the other national medicines agencies in the EU are currently investigating and assessing cases of blood clots, low level of platelets and bleeding. At present, there is no evidence to conclude that these incidents are linked to the vaccine. 

Read more in the previous status announcements on monitoring of the COVID-19 Vaccine AstraZeneca:

18 March: News on the website of the Danish Medicines Agency: Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 140,000 Danes (in Danish only)

11 March: News on the website of the Danish Medicines Agency: Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 136,090 Danes (in Danish only)

4 March: News on the website of the Danish Medicines Agency: Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 87,000 Danes (in Danish only)

25 March: News on the website of the Danish Medicines Agency: Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 43,000 Danes (in Danish only)

18 March: News on the website of the Danish Medicines Agency: Status on reviewed reports of suspected side effects of the COVID-19 Vaccine AstraZeneca after vaccination of more than 18,000 Danes (in Danish only)

Danish Medicines Agency’s COVID-19 theme page

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