tetano
Editor, Senior Moderator
Travel Med Infect Dis
. 2022 Feb 2;102271.
doi: 10.1016/j.tmaid.2022.102271. Online ahead of print.
SARS-CoV-2 RT-PCR positivity of individuals subsequent to completing quarantine upon entry into a country during a transmission-free period
Sirawat Srichatrapimuk[SUP] 1 [/SUP], Thanat Chookajorn[SUP] 2 [/SUP], Theerarat Kochakarn[SUP] 2 [/SUP], Suppachok Kirdlarp[SUP] 1 [/SUP], Ekawat Pasomsu[SUP] 3 [/SUP], Wasun Chantratita[SUP] 4 [/SUP], Sopon Iamsirithaworn[SUP] 5 [/SUP], Mongkol Kunakorn[SUP] 3 [/SUP], Arunee Thitithanyanont[SUP] 6 [/SUP], Somnuek Sungkanuparph[SUP] 1 [/SUP], Angsana Phuphuakrat[SUP] 7 [/SUP]
Affiliations
Abstract
Background: During the current coronavirus disease 2019 (COVID-19) pandemic, many countries require travellers to undergo a reverse transcription-polymerase chain reaction (RT-PCR) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before travelling across borders. However, in persons having recovered from COVID-19, RT-PCR positivity can persist for an extended period.
Materials and methods: We describe three cases who sought fit-to-fly certificates in Thailand during the period free of local transmission but were tested positive for RT-PCR for SARS-CoV-2. All had returned from a country with an active outbreak of COVID-19. Their clinical courses are described; positive nasopharyngeal swab samples were processed for viral isolation and whole-genome sequencing (WGS); and serology as well as neutralizing antibody were assessed. The contact tracing was carried out for determining evidence of indigenous transmission among close contacts of those three cases.
Results: All three cases were completely asymptomatic. Chest computerized tomography was not compatible with COVID-19 pneumonia; cell cultures failed to rescue replication-competent virus; WGS revealed fragmented viral genetic material from nasopharyngeal swab samples; and serological tests demonstrated stable levels of antibodies, together with the presence of neutralizing antibody, suggesting past infection with negligible transmission risk. Contact tracing identified no transmission in high-risk close contact individuals.
Conclusion: RT-PCR positivity for SARS-CoV-2 might detect fragmented viral genome. Issuance of a travel certificate in these circumstances is problematic. Serology tests can help to define past infection. A practical acceptable set of guidelines for issuance of a COVID-19 safety travel certification is a necessity.
Keywords: COVID-19; RT-PCR; SARS-CoV-2; Serology; Travel certificate.
. 2022 Feb 2;102271.
doi: 10.1016/j.tmaid.2022.102271. Online ahead of print.
SARS-CoV-2 RT-PCR positivity of individuals subsequent to completing quarantine upon entry into a country during a transmission-free period
Sirawat Srichatrapimuk[SUP] 1 [/SUP], Thanat Chookajorn[SUP] 2 [/SUP], Theerarat Kochakarn[SUP] 2 [/SUP], Suppachok Kirdlarp[SUP] 1 [/SUP], Ekawat Pasomsu[SUP] 3 [/SUP], Wasun Chantratita[SUP] 4 [/SUP], Sopon Iamsirithaworn[SUP] 5 [/SUP], Mongkol Kunakorn[SUP] 3 [/SUP], Arunee Thitithanyanont[SUP] 6 [/SUP], Somnuek Sungkanuparph[SUP] 1 [/SUP], Angsana Phuphuakrat[SUP] 7 [/SUP]
Affiliations
- PMID: 35123068
- DOI: 10.1016/j.tmaid.2022.102271
Abstract
Background: During the current coronavirus disease 2019 (COVID-19) pandemic, many countries require travellers to undergo a reverse transcription-polymerase chain reaction (RT-PCR) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before travelling across borders. However, in persons having recovered from COVID-19, RT-PCR positivity can persist for an extended period.
Materials and methods: We describe three cases who sought fit-to-fly certificates in Thailand during the period free of local transmission but were tested positive for RT-PCR for SARS-CoV-2. All had returned from a country with an active outbreak of COVID-19. Their clinical courses are described; positive nasopharyngeal swab samples were processed for viral isolation and whole-genome sequencing (WGS); and serology as well as neutralizing antibody were assessed. The contact tracing was carried out for determining evidence of indigenous transmission among close contacts of those three cases.
Results: All three cases were completely asymptomatic. Chest computerized tomography was not compatible with COVID-19 pneumonia; cell cultures failed to rescue replication-competent virus; WGS revealed fragmented viral genetic material from nasopharyngeal swab samples; and serological tests demonstrated stable levels of antibodies, together with the presence of neutralizing antibody, suggesting past infection with negligible transmission risk. Contact tracing identified no transmission in high-risk close contact individuals.
Conclusion: RT-PCR positivity for SARS-CoV-2 might detect fragmented viral genome. Issuance of a travel certificate in these circumstances is problematic. Serology tests can help to define past infection. A practical acceptable set of guidelines for issuance of a COVID-19 safety travel certification is a necessity.
Keywords: COVID-19; RT-PCR; SARS-CoV-2; Serology; Travel certificate.