Question & Answer

If I've already had COVID-19 am I immune to re-infection?

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  • “Corona”, in Latin, means crown. The coronavirus has an outer layer of protein covered in spikes, like a crown. These spikes help the virus attach itself to particular cells in our body. When the virus SARS-CoV-2 (the virus that causes COVID-19) attacks, the body creates antibodies. Antibodies are molecules that our immune systems make in response to invading viruses and other things that cause disease, and some antibodies can help to provide protection or immunity against getting that infection again. Immunity can be strong or weak, short-lived or long-lasting.
  • Fewer than 10% of the general population have detectable COVID-19 antibodies.
  • In their COVID-19 immune response update, the World Health Organisation (WHO) notes that most COVID-19 patients who recovered will have antibodies to the virus detectable in their blood.
  • However, the WHO also highlights several studies which show that antibodies for COVID-19 may disappear after 3 months.
  • The WHO suggests that “patients who have had more severe disease appear to have higher levels of antibodies whereas patients who had mild or asymptomatic COVID-19 have low levels of antibodies”.
  • There have been a number of reported cases of reinfection, but none of those cases have been confirmed with rigorous testing. The first confirmed case of reinfection of COVID-19 occurred in Hong Kong. The WHO confirmed this as the first documented case of reinfection out of more that 23 million cases of COVID-19.
  • There has been no confirmed case of COVID-19 reinfection reported by the Health Service Executive in Ireland.
  • There are ongoing studies in the UK to explore whether we can generate long-lasting antibody responses to COVID-19.
  • The WHO states that many countries are now testing for COVID-19  antibodies in the general population and in specific groups such as health workers, close contacts of known cases, or within households. They advise that these studies “are not designed to determine whether those people are immune to secondary infection” but to to provide information to understand and respond to the COVID-19 pandemic.
  • Until a vaccine or better treatment is available, we should continue to follow public health guidance: practise social distancing (remain 2 metres from people other than those you live with), wear a face mask, cough and sneeze into a tissue or the crook of your elbow and wash hands properly and regularly.

Things to Remember


  • Lead Researcher: Dr Michelle Queally, Department of Economics, 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, University College Cork. 
  • Evidence Advisor: Casey Donaghey, PPI Ignite, NUI Galway.
  • Journalist Advisor: Dr Claire O’Connell, Contributor, The Irish Times.