








key: cord-260247-akujsk0s
authors: Hamed, Ehab
title: Rates of recurrent positive SARS-CoV-2 swab results among patients attending primary care in Qatar
date: 2020-11-02
journal: J Infect
DOI: 10.1016/j.jinf.2020.10.029
sha: 
doc_id: 260247
cord_uid: akujsk0s

nan

We read with interest the work of COCOREC (Collaborative study COvid RECurrences) study group 1 . Recurrent positive rt-PCR results for SARS-CoV-2 infection were reported from early in the epidemic [1] [2] [3] [4] [5] [6] [7] [8] . Viral genomic sequences provided concrete evidence for reinfection by distinct SARS-CoV-2 infection [9] [10] [11] [12] . The number of days in between both infections in viral genomic proven reports ranged from 48 to 142 days.

While viral genomic sequencing provides robust evidence, it does not lend itself well to everyday practice. The COCOREC study identified 11 cases of reinfection using well-defined criteria 1 . The group suggested recurrent positive rt-PCR results of more than 21 days following the resolution of symptoms as criteria for reinfection. The criteria though less specific, are more feasible to use in primary health care settings.

Utilising the criteria set by the COCOREC study group, this record-based study reports on the cases with recurrent positive RT-PCR nasopharyngeal swab for SARS-CoV-2 results in primary health care corporation (PHCC) settings in Qatar. PHCC is the largest primary care provider in Qatar with 27 health centers covering all the country. The organisational employs an electronic medical record (EMR), which links all public primary health care centers. For this study, all electronic data were extracted from the primary healthcare setting visits, and no sampling was needed.

The study population included patients attending with documented SARS-CoV-2 rt-PCR results during the study period. The study period was from February 10 th , 2020, to July 30 th , 2020, a total of 171 days. The recurrent positive population included all patients with a minimum number of 2 positive swabs and a minimum number of 21 days in between positive swab results. Inconclusive and reactive rt-PCR results were considered negative. During the study period, patients were entitled to a repeat swab if they are attending with new symptoms following the resolution of initial symptoms. A maximum number of days in between any positive swab results was calculated for those who met our definition criteria.

The study aims to answer the following questions. What is the maximum number of days in between positive swab results? What are the rates of recurrent rt-PCR SARS-CoV-2 positive results of more than 21 days, and what are the population characteristics?

During the study period, we retrieved a total of 63444 patient records with 76742 swab results. Only 62 patients met our inclusion criteria (62/63444;0.1%).

The population was predominantly young. The mean age is 37. 3 The rates for recurrent positive results are reported for the total recurrent positive (62) and the total study population, (63444). The recurrent positive results of more than 42 days were rare (7/63444,0.01%) (table 2) . 

Recurrent positive findings could occur in all age groups and different population types, including paediatric, elderly, and pregnant patients. Current smoking status was highly prevalent among patients with recurrent positive results.

No previous studies reported to the rates of recurrent positive rt-PCR for SARS-CoV-2 infections. Given the extensive reporting of the SARS-CoV-2 infections, the number of case reports of recurrent positive and reinfection to date is extremely low, which agrees with our findings. Earlier studies reported that viral shedding is dynamic and continue in most cases 20-22 days but positive results were generally rare beyond 30 days 13 . So, one could theorise that recurrent positive results in symptomatic patients should be considered reinfection, especially if more than 42 days.

The rare occurrences of recurrent infections are reassuring to the world given the current surge and in favour of immunity. However, it does not allude to the length of that immunity. Given the rarity of recurrent positive results which is supported by our findings, vaccination should be recommended for patients with no earlier SARS-CoV-2 infection.

The study utilised centralised database records that allowed for large sample size, 63444 and long study period of 6 months. However, the record-based study does not report on the severity or the resolution of symptoms or the patients' outcomes.

Data request and analysis were anonymous, and no patient consent was required.

Anonymous data request approved by the department of clinical research, primary health care corporation with reference number PHCC/DCR/2020/04/031.

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We acknowledge the support we receive from the Primary Health Care Corporation (PHCC) research department.

