From the Guidelines
Patients with COVID-19 should self-isolate for 10 days with mild to moderate disease, or 15–20 days with severe illness to protect staff, other patients, and members of the public. This recommendation is based on the most recent and highest quality study available, which suggests that symptoms of COVID-19 present 4–5 days following infection with SARS-CoV-2, and it is most contagious in the 2 days before and the 5 days after the onset of symptoms 1.
Key Considerations for Isolation
- In asymptomatic and mild to moderately symptomatic patients, it is rare for the virus to be cultured beyond 10 days after symptom onset, which underlies both UK and World Health Organization recommendations for self-isolation of 10 days following a positive SARS-CoV-2 PCR test 1.
- In the severely ill or severely immunocompromised patients, infectivity may continue for longer, with the risk of replication-competent virus being approximately 5% at 15 days after symptom onset and extremely rare at 20 days 1.
- Those who are severely immunocompromised may need specialist advice on duration of self-isolation, as PCR positivity does not correlate with secretion of live virus, so is of little or no value in assessing the risk of infectivity in the 3 months after confirmed SARS-CoV-2 infection 1.
Implications for Healthcare Services
- Planned surgery should not be considered during the period that a patient may be infectious, and when emergency surgery is required during this period, full transmission-based precautions should be undertaken 1.
- Patients should self-isolate for the recommended period before attending any hospital services to minimize the risk of transmission to staff, other patients, and members of the public.
From the Research
Isolation Guidelines for COVID-19
The isolation guidelines for Coronavirus Disease (COVID-19) have been studied in various research papers.
- According to a study published in 2023, the US guidelines recommend isolation for 5 days from symptom onset, followed by 5 days of mask-wearing 2.
- A longitudinal cohort study found that 17% of participants had positive cultures beyond day 5 from symptom onset, with the latest on day 12, suggesting that some individuals may still be infectious after the recommended isolation period 2.
- Another study published in 2022 investigated the impact of two different COVID-19 patient isolation time strategies on healthcare workers' contamination and nursing care intensity, and found that a shorter isolation time was not associated with higher healthcare worker contamination 3.
- The optimal isolation time for COVID-19 patients is still debated, and more research is needed to determine the most effective isolation strategies.
Key Findings
- The majority of participants in a study infected with Delta and Omicron variants culture-converted by day 6, with no further impact of booster vaccination on sterilization or cycle threshold decay 2.
- Rapid antigen testing may provide reassurance of lack of infectiousness, though guidance to mask for days 6-10 is supported by the finding that 17% of participants remained culture-positive after isolation 2.
- A longer isolation time was associated with accidental extubation, but neither with ventilator-associated pneumonia nor with dysglycemia 3.
Isolation Time Strategies
- Different isolation time strategies have been studied, including isolation for 5 days from symptom onset, followed by 5 days of mask-wearing 2, and isolation for 14 days after the onset of symptoms 3.
- The choice of isolation time strategy may depend on various factors, including the severity of the disease, the patient's vaccination status, and the risk of transmission to others.