From the Guidelines
Individuals with COVID-19 should isolate for at least 10 days from symptom onset, or 15-20 days for severely ill or immunocompromised patients, to minimize the risk of transmission to others. The most recent and highest quality study 1 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.
Key Considerations for Isolation and Masking
- Isolation duration: 10 days for mild to moderate disease, and 15-20 days for severe illness or immunocompromised patients 1
- Masking: wear a high-quality mask (like an N95 or KN95) around others for an additional 5 days after ending isolation
- Ventilation and hygiene: stay in a separate room from household members, use a separate bathroom if possible, and improve ventilation to reduce transmission risk
- Hand hygiene: regular hand hygiene and disinfection of high-touch surfaces further reduce transmission risk 1
Special Considerations
- Immunocompromised individuals: may need to consult healthcare providers about testing before ending isolation and should isolate longer 1
- Severe illness: patients with severe illness should isolate for at least 15-20 days 1
- Moderate illness: patients with moderate illness should isolate for at least 10 days 1
Prevention of Transmission
- Mask use and hand hygiene are strong recommendations for prevention of viral transmission 1
- Social distancing and proper ventilation can also reduce the risk of transmission 1
From the Research
Isolation Guidelines for COVID-19
- Individuals with COVID-19 are advised to self-isolate at their residences unless they require hospitalization 2.
- The duration of self-isolation is typically around 10 days for mild-moderately ill patients and 15 days for severely-critically ill and immunocompromised patients 3.
- However, some studies suggest that a more cautious approach may be necessary, with a longer duration of self-isolation, especially for patients who still show detectable viral RNA despite meeting CDC guidelines for discontinuation of self-isolation 4.
Mask Guidelines for COVID-19
- Wearing masks is an effective measure to reduce the transmission of SARS-CoV-2, especially from asymptomatic individuals 5.
- Masks should be worn in public places, especially in areas with high transmission rates, to reduce the risk of transmission.
- Individuals with COVID-19 should wear masks when interacting with others, even if they are self-isolating, to prevent transmission to others.
Transmission and Infectivity
- SARS-CoV-2 is most contagious around the time of symptom onset, and infectivity rapidly decreases thereafter to near-zero after about 10 days in mild-moderately ill patients and 15 days in severely-critically ill and immunocompromised patients 3.
- Asymptomatic transmission accounts for a significant proportion of SARS-CoV-2 transmissions, with estimates suggesting that at least 50% of new infections originate from exposure to individuals with infection but without symptoms 5.
- The size distribution of SARS-CoV-2-laden aerosol particles suggests a risk of aerosol transmission, especially in indoor settings 2.
Control of Outbreaks
- Isolation of cases and contact tracing is a effective strategy to control outbreaks of COVID-19, especially if implemented quickly and with high contact tracing probability 6.
- The delay between symptom onset and isolation has a significant impact on the controllability of an outbreak, with longer delays reducing the effectiveness of control measures 6.
- Highly effective contact tracing and case isolation can control a new outbreak of COVID-19 within 3 months, but the probability of control decreases with increasing transmission before symptoms and long delays from symptom onset to isolation 6.