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Is there any evidence that a second dose of a COVID-19 vaccine can directly lead to adverse effects or death?

This article was published on
April 22, 2021

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Most vaccines and medications cause side effects, but there is no evidence to support the claim that a second COVID-19 vaccine injection can lead to death. Some severe side effects like blood clots are possibly linked to the AstraZeneca and Johnson & Johnson vaccines in very rare cases, but there is not enough evidence to determine whether or not the vaccines are associated with this adverse effect. Not all vaccines have two doses. Of the vaccines that do, some are just now beginning to roll out, including those with little data. Though people have died after receiving vaccines, there have been no direct reports that have noted vaccines were the reason those people died.

Most vaccines and medications cause side effects, but there is no evidence to support the claim that a second COVID-19 vaccine injection can lead to death. Some severe side effects like blood clots are possibly linked to the AstraZeneca and Johnson & Johnson vaccines in very rare cases, but there is not enough evidence to determine whether or not the vaccines are associated with this adverse effect. Not all vaccines have two doses. Of the vaccines that do, some are just now beginning to roll out, including those with little data. Though people have died after receiving vaccines, there have been no direct reports that have noted vaccines were the reason those people died.

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What our experts say

Almost every medication or vaccine includes some side effects. Many people who receive flu shots or even shingles vaccines are likely to have sore arms and some redness where they received the jab. The second dose of some COVID-19 vaccines can cause common side effects including muscle aches, fever, fatigue, diarrhea, nausea and more.

Some COVID-19 vaccines have been potentially linked to extremely rare but severe side effects. AstraZeneca and Johnson & Johnson vaccines may be potentially linked with very rare forms of blood clots, some of which could lead to the possibility of deaths. However, there has been no conclusive link between the vaccines and the blood clots. The United Nations noted that there is a "plausible" connection between the AstraZeneca vaccine and blood clots but the World Health Organization is still investigating this issue.

National and international drug regulation agencies are evaluating whether or not these vaccines can cause or be linked to blood clots. In the meantime it is important to note that people infected with COVID-19 are 100 times more likely to develop blood clotting than people who were not infected.

The risk of getting a blood clot after a COVID-19 infection is shown to be eight times higher than the risk of a blood clot after the AstraZeneca COVID-19 vaccine. Blood clots in the general population are relatively common so it's important to remember that though these might be rarely associated with vaccines, they are happening in vaccinated people at a rate that is much lower than naturally occurs in large populations.

Other vaccines have less peer-reviewed data to evaluate. However, the Sputnik V vaccine, CoronaVac and Covaxin have not been associated with excess mortality in studies as of April 21, 2021. To be sure, early data showed some reports of serious side effects after first shots of both the CoronaVac and AstraZeneca vaccines in the Philippines. These reports were rare — 137 out of 240,000 administered in the country.

The Pfizer-BioNTech vaccine has been shown to be safe and is not linked to deaths or widespread severe side effects in several scientific journals. It is challenging for doctors and researchers to confirm that a vaccine directly led to a person's death, especially as such large numbers of people are getting vaccinated.

Until more data is available for all vaccines over a longer period of time, conclusive evidence about their potential side effects is not available. Each country's national regulatory agencies determine whether or not they believe each vaccine is safe and effective for their populations. If a COVID-19 vaccine could directly lead to death, it is highly unlikely regulatory agencies would approve their use.

Context and background

As more people receive COVID-19 vaccines around the world, the likelihood of seeing more side effects linked to them is high. There is no way clinical trials can capture all the potential responses each person will have to the shots. Each country's health regulatory agencies, the World Health Organization, and other international bodies evaluate whether or not a vaccine is safe for wide distribution among millions of people. If these organizations are concerned about potential side effects or deaths, they generally pause vaccine rollouts until they can research the cause of those issues.

Resources

  1. What do we know about China’s covid-19 vaccines? (British Medical Journal)
  2. COVID vaccines and safety: what the research says (Nature)
  3. COVID-19 Vaccine Janssen: EMA finds possible link to very rare cases of unusual blood clots with low blood platelets (European Medicines Agency)
  4. Bharat Biotech and ICMR Announce Interim Results from Phase 3 trials of COVAXIN®; Demonstrates overall Interim Clinical Efficacy of 78% and 100% efficacy against Severe COVID-19 disease (Bharat Biotech)
  5. China's Coronavac 80% effective at preventing Covid deaths: Chile results (France 24)
  6. Covid-19: What do we know about Sputnik V and other Russian vaccines? (British Medical Journal)
  7. EMA starts rolling review of the Sputnik V COVID-19 vaccine (European Medicines Agency)
  8. Sputnik V: How Russia's Covid vaccine is dividing Europe (BBC News)
  9. Types of vaccine (University of Oxford)
  10. Possible Side Effects After Getting a COVID-19 Vaccine (U.S. Centers for Disease Control and Prevention)
  11. AstraZeneca Vaccine Unfairly Under Fire Over Clot Risk? (Medpage Today)
  12. Cerebral venous thrombosis: a retrospective cohort study of 513,284 confirmed COVID-19 cases and a comparison with 489,871 people receiving a COVID-19 mRNA vaccine (Center for Open Science)
  13. Blood clots: The good, the bad, and the deadly (Harvard Medical School)
  14. Fact check: No links found between vaccination and deaths (Deutsche Welle)
  15. AstraZeneca Vaccine and Blood Clots: What Is Known So Far (New York Times)
  16. Study: COVID much more likely than vaccines to cause blood clots (Center for Infectious Disease Research and Policy)
  17. BACK TO #VACCINESWORK What is the blood clotting disorder the AstraZeneca vaccine has been linked to? (Gavi The Vaccine Alliance)
  18. COVID vaccines and blood clots: five key questions (Nature)
  19. Is there a cure for COVID-19? (Department of Health of the Philippines)
  20. Philippines approves emergency use of J&J, Bharat BiotechCOVID-19 vaccines (Reuters)
  21. COVID-19 vaccines (Harvard Medical School)
  22. What doctors wish patients knew about the Johnson & Johnson vaccine (American Medical Association)
  23. Interim statement of the COVID-19 subcommittee of the WHO Global Advisory Committee on Vaccine Safety on AstraZeneca COVID-19 vaccine (World Health Organization)
  24. ‘Plausible’ link between AstraZeneca vaccine and rare blood clots, WHO committee says (United Nations News)
  25. COVID-19 Vaccine Janssen: EMA finds possible link to very rare cases of unusual blood clots with low blood platelets (European Medicines Agency)
  26. Selected Adverse Events Reported after COVID-19 Vaccination (U.S. Centers for Disease Control and Prevention)

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