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 target cells in the body. When a virus-like 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.
  • There have been reports of suspected COVID-19 reinfection, where someone who had the virus is reported to have caught the virus a second time, however, no confirmed case of COVID-19 reinfection has been reported by the World Health Organisation or by the Health Service Executive in Ireland.
    1. There is currently no conclusive evidence to suggest that the presence of antibodies to SARS-CoV-2 (COVID-19), developed after initial infection, provides immunity to re-infection by this virus.
    2. There is no conclusive evidence about how long antibodies last for within an individual.
    3. There is no conclusive evidence about how effective these antibodies are at fighting the virus in a person.
  • It has been suggested that the detection of antibodies to the SARS-CoV-2 could serve as the basis for an “immunity passport”. This passport would be given to individuals who have had COVID-19, based on the assumption they would be immune to reinfection. In response, the World Health Organization issued a statement warning against issuing immunity passports, as there is no current evidence that people will be protected from a second infection, even if they have made antibodies to the virus.
  • A study of 175 patients with mild symptoms of COVID-19 in China found that most patients (70%) developed a strong antibody response; one in four (25%) developed a low antibody response; and 5% had no antibody response. However, we don’t know yet how long the antibodies last. In 2003, a study of patients infected with severe acute respiratory syndrome (SARS), which belongs to the family of coronaviruses, found that antibodies begin to decrease after about four months, but are present in most people for two years. By year three, up to a quarter of patients no longer had detectable antibodies, and after six years, almost no one
  • There are ongoing studies in the UK to explore whether we can generate long-lasting antibody responses to Sars-Cov-2.
  • The World Health Organisation state that many countries are now testing for SARS-CoV-2 antibodies at the population level or in specific groups, such as health workers, close contacts of known cases, or within households but advise these studies “are not designed to determine whether those people are immune to secondary infection”.
  • Until a vaccine or 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), cough and sneeze into a tissue or the crook of your elbow and wash hands properly and regularly.

Things to Remember

Reviewers

  • 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.