Question & Answer

Is COVID-19 caused by a bacterial infection?

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  • In May and June 2020, claims were circulated on social media that COVID-19 is a bacterial infection, not a viral infection.
  • Bacteria are different from viruses in many ways, and we often use different medicines and approaches to help people who have bacterial infections (for example, antibiotics) compared to viral infections (where antibiotics will not kill the virus).
  • COVID-19 is a disease caused by the SARS-CoV-2 virus, which is a coronavirus (HSE, 2020).
  • Coronaviruses are a large family of viruses which can cause illnesses in animals or humans.  In humans, coronaviruses are known to cause respiratory illnesses ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS), Severe Acute Respiratory Syndrome (SARS) (World Health Organization, 2020), and SARS-CoV-2 (also called COVID-19).
  • The SARS-CoV-2 virus has been carefully studied in laboratories all over the world. Scientists track the spread of the virus by comparing samples of COVID-19 genomes (the genetic material that the virus contains) in different parts of the world.
  • Although uncommon, some people who become ill with COVID-19 may develop a bacterial infection as a complication. This is called a secondary infection. In these cases, the use of antibiotics may be recommended by health care providers on a case to case basis (World Health Organization, 2020).
  • Antibiotics are not effective against viral infections (HSE, FDA, NHS, CDC) of any type, including SARS-CoV-2.  Antibiotics are effective for treating bacterial infections.
  • To protect yourself and others from coronavirus, please continue to follow public health advice to maintain social distancing and wash your hands properly and often.

Things to Remember


  • Lead Researcher: Dr Eimear Morrissey, School of Medicine and School of Psychology, NUI Galway.
  • Reviewed by: Elaine Finucane, HRB-Trials Methodology Research Network, School of Nursing and Midwifery, NUI Galway.
  • Evidence Advisor: Dr Frances Shiely, HRB Clinical Research Facility and the School of Public Health, UCC.
  • Evidence Advisor: Casey Donaghey, PPI Ignite, NUI Galway.
  • Journalist Advisor: Dr Claire O’Connell, Contributor, The Irish Times.