Non-infectious status indicated by detectable IgG antibody to SARS-CoV-2

David W Denning, Anthony Kilcoyne, Cemal Ucer

Research output: Contribution to journalComment/debatepeer-review


A key tenet of protection from infection for dentists is to know who is not infectious. The evidence base regarding protection from respiratory pathogens in dentistry is poor. Those with a positive SARS-CoV-2 IgG antibody are non-infectious (>99% certainty) and can be safely treated with good universal precautions, even for aerosol generating procedures. Viral infectivity with SARS-CoV-2 lasts eight days, unlike viral polymerase chain reaction (PCR) swab tests which can persist for as long as seven weeks. SARS-CoV-2 IgG antibody becomes detectable from 11 days after infection. SARS-CoV-2 IgG antibodies are usually neutralising against the virus and their direct antiviral activity was partially demonstrated in 33,000 patients with COVID-19 treated with convalescent plasma in the USA. So, a positive SARS-CoV-2 IgG antibody is a much more accurate determination of infectiousness than a repeat PCR which is only 70% sensitive. It remains to be seen whether SARS-Cov-2 vaccine responses include protective IgG titres and, once vaccines become widespread, can be used to assist decision-making on appropriate personal protective equipment (PPE) in dentistry.

Original languageEnglish
Pages (from-to)521-524
Number of pages4
JournalBritish Dental Journal
Issue number8
Publication statusPublished - 23 Oct 2020


  • Antibodies, Viral
  • Betacoronavirus
  • COVID-19
  • COVID-19 Vaccines
  • Coronavirus Infections/prevention & control
  • Humans
  • Immunization, Passive
  • Immunoglobulin G
  • Pandemics
  • Pneumonia, Viral
  • Severe acute respiratory syndrome-related coronavirus
  • SARS-CoV-2
  • Viral Vaccines
  • COVID-19 Serotherapy


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