Infectivity Period After Symptom Relief in SARS-CoV-2 Patients: An Experimental Trial

This study aimed to understand the infectivity period after symptom relief in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients using real-time reverse transcription polymerase chain reaction (RT-PCR). This would probably help prevent the disease spread by partially recovered patients to some extent.

A total of 10 coronavirus disease 2019 (COVID-19) infected patients with mild to moderate illness, approved by RT-PCR, were followed daily. After 2 days of cessation of clinical symptoms, a nasopharyngeal and oropharyngeal sample RT-PCR was taken. If the patients’ test had a negative result, a repeated RT-PCR was performed 24 hours later. Moreover, if two consecutive tests had negative results, the patient was considered definitively treated, and the follow-up was terminated. However, if RT-PCR was positive, the test was performed 3 days later. The infectivity period after symptom relief and total infectivity period were calculated. The SARS-CoV-2 immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies were measured 1 month after symptom relief. The SPSS Software (version 20) was used for data analysis.

A total of 10 patients met the inclusion criteria to enter the study. There were 6 (60%) male and 4 (40%) female patients. The mean age of patients was 37.40 ± 7.975 years (minimum: 28 years, maximum: 51 years). The mean days passed from the onset of symptoms at the time of referring to Kowsar Hospital in Semnan, Iran, was 3.2 ± 0.919 days (minimum: 2 days, maximum: 5 days). The mean infectivity period after symptom relief was 6.9 ± 5.152 days indicating that it took about 7 days after symptom relief that the patients were considered completely treated according to RT-PCR results. However, the mean period of total infectivity was 16.6 ± 5.73 days. Moreover, 70% of patients had an IgM negative/IgG positive result 1 month after symptom relief; nevertheless, 30% of patients showed a delayed antibody response.

The virus could be detected in nasopharyngeal and oropharyngeal samples in the studied patients up to 7 days after symptom relief. This finding highlights the importance of isolation and distancing in patients after recovery and the adoption of hygiene measures.