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Letter to the editor|Articles in Press

Care home SARS-CoV-2 outbreaks are highly dependent on the immunocompetence of the infected people

Published:March 20, 2023DOI:https://doi.org/10.1016/j.jhin.2023.03.007
Care home SARS-CoV-2 outbreaks are highly dependent on the immunocompetence of the infected people
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      Sir,
      I read with interest the article by Cotton et al. on a clinical and genetic study investigating whether patients discharged from hospitals to care homes were the source of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) introduction into care homes during the first epidemic wave [
      • Cotton S.
      • McHugh M.P.
      • Dewar R.
      • Haas J.G.
      • Templeton K.
      COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
      J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
      ]. The study was carried out over a 3-month period in Lothian, Scotland [
      • Cotton S.
      • McHugh M.P.
      • Dewar R.
      • Haas J.G.
      • Templeton K.
      COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
      J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
      ]. It was concluded that most outbreaks during care homes in the first wave were not sourced by patients discharged from hospitals, and that infection control strategies should focus on all admissions and sources into the care home when faced with a novel emerging virus with no available vaccine [
      • Cotton S.
      • McHugh M.P.
      • Dewar R.
      • Haas J.G.
      • Templeton K.
      COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
      J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
      ]. This study is excellent, but has limitations that are cause for concern and should be discussed.
      SARS-CoV-2 can be transmitted to nursing home residents not only by returnees from hospitals, new residents from the community, new residents from other nursing homes, visitors and staff, but also by transmission of the virus between residents, via animals, and by water or food intake.
      Infection rates and death rates reached high levels in care homes. These could be affected by the high number of comorbidities in elderly patients, and immunosuppression due to chronic drug use. Information about the comorbidities found in the patients included in the study, and what medications these patients were taking regularly, would be useful.
      A limitation of the study by Cotton et al. [
      • Cotton S.
      • McHugh M.P.
      • Dewar R.
      • Haas J.G.
      • Templeton K.
      COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
      J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
      ] was that patients were tested with reverse transcriptase polymerase chain reaction (RT-PCR) if they had a fever or cough. However, coronavirus disease 2019 (COVID-19) does not only manifest itself in the lungs, but also has extrapulmonary manifestations [
      • Finsterer J.
      • Scorza F.A.
      • Scorza C.A.
      • Fiorini A.C.
      Extrapulmonary onset manifestations of COVID-19.
      Clinics (Sao Paulo). 2021; 76e2900
      ]. Therefore, as the decision to perform or not perform RT-PCR was based on the clinical presentation of fever and cough, many cases with extrapulmonary manifestations may have been missed initially.
      Another limitation is that swab tests, which are usually performed to screen patients for SARS-CoV-2, can be negative despite existing SARS-CoV-2 infection. As well as the sensitivity of the applied test, this may be due to the fact that COVID-19 can manifest itself with extrapulmonary manifestations, even at the beginning of the infection [
      • Finsterer J.
      • Scorza F.A.
      • Scorza C.A.
      • Fiorini A.C.
      Extrapulmonary onset manifestations of COVID-19.
      Clinics (Sao Paulo). 2021; 76e2900
      ]. Based on these considerations, it is very likely that some infected residents were missed.
      The 14-day limit for infectivity of an infected patient is somewhat arbitrary. The infectious period is highly dependent on the immunocompetence of the infected patient and the organ in which the virus lodges. Due to longer infectious periods, an extension of the isolation period to 20 days has been suggested, especially for severe cases [
      • Byrne A.W.
      • McEvoy D.
      • Collins A.B.
      • Hunt K.
      • Casey M.
      • Barber A.
      • et al.
      Inferred duration of infectious period of SARS-CoV-2: rapid scoping review and analysis of available evidence for asymptomatic and symptomatic COVID-19 cases.
      BMJ Open. 2020; 10e039856
      ].
      Overall, this interesting study by Cotton et al. [
      • Cotton S.
      • McHugh M.P.
      • Dewar R.
      • Haas J.G.
      • Templeton K.
      COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
      J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
      ] has limitations that call the results and their interpretation into question. Addressing these issues would strengthen the conclusions and could improve the status of the study. Care home outbreaks are not associated with patients discharged from hospital but with infections within care homes, and are highly dependent on the immunocompetence of the infected people.

      Conflict of interest statement

      None declared.

      Funding sources

      None.

      References

        • Cotton S.
        • McHugh M.P.
        • Dewar R.
        • Haas J.G.
        • Templeton K.
        COVID-19 Genomics UK (COG-UK) Consortium. Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes.
        J Hosp Infect. 2023; https://doi.org/10.1016/j.jhin.2023.02.010
        View in Article
        • Finsterer J.
        • Scorza F.A.
        • Scorza C.A.
        • Fiorini A.C.
        Extrapulmonary onset manifestations of COVID-19.
        Clinics (Sao Paulo). 2021; 76e2900
        View in Article
        • Byrne A.W.
        • McEvoy D.
        • Collins A.B.
        • Hunt K.
        • Casey M.
        • Barber A.
        • et al.
        Inferred duration of infectious period of SARS-CoV-2: rapid scoping review and analysis of available evidence for asymptomatic and symptomatic COVID-19 cases.
        BMJ Open. 2020; 10e039856
        View in Article

      Article info

      Publication history

      Published online: March 20, 2023
      Accepted: March 16, 2023
      Received: March 13, 2023

      Publication stage

      In Press Journal Pre-Proof

      Identification

      DOI: https://doi.org/10.1016/j.jhin.2023.03.007

      Copyright

      © 2023 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

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