Contact Tracing
Legitimate Contact

Isolation keeps someone who is sick or tested positive for COVID-19 without symptoms away from others, even in their own home.
Home Isolation Guidance
The guidelines below reflect the most recent recommendations by CDC and CDPH (California Department of Public Health). They are available to you as an option, though risk of transmission may exist past 5 days. Isolating away from others for 10 days continues to be the safest option.
Persons Who Test Positive for COVID-19 (Isolation) |
Recommended Action |
If you have tested positive for COVID, you will need to isolate regardless of vaccination status or lack of symptoms |
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Masking Guidance:
Wearing a well-fitting mask is essential to protecting others through 10 days after your infection starts. For information on how to use masks most effectively, please refer to Get the Most out of Masking.
When Can I Leave Isolation? Please see the following 1-page document for Isolation Guidance (updated 2022.04.1): English | (updated 2022.03.22): Arabic | Chinese (Traditional) | Dari | Farsi | Hindi | Khmer | Korean | Mongolian | Pashtu | Punjabi | Spanish | Tagalog | Tigrinya | Vietnamese
Quarantine keeps a person who was in close contact with someone who has COVID-19 away from others.
In line with recommendations from California Department of Public Health, most individuals do not have to quarantine after an exposure to COVID-19. There are, however, steps people should take to reduce the risk of spread.
Close Contact & Quarantine Guidance
Changing conditions mean that quarantine (keeping exposed – but not yet symptomatic or known to be infected – individuals away from others) is now a less effective strategy for preventing the spread of COVID-19 outside of high-risk settings. The virus that causes COVID-19 has evolved to have a shorter incubation period (the time between exposure and becoming ill). The virus can also spread from person to person at greater distances, especially indoors. Tools such as testing and mask-wearing are still very important after an exposure to someone with COVID-19. If you develop symptoms, isolate immediately and test for COVID-19.
Staying up to date on vaccination continues to be the best way to prevent hospitalization or death from COVID-19. If someone who is at high-risk for severe disease becomes infected, there are prescription pills (and outpatient antibody infusions) available that provide protection against hospitalization and death. The costs of these medications are free, but they must be started within a few days after symptoms begin. Don’t wait until symptoms get worse.
If you believe you have been exposed to COVID-19, you are strongly encouraged to take the actions listed below to protect yourself and others. While you do not need to quarantine, consider avoiding people at high-risk for severe COVID-19 disease for 10 days such as: older adults, people living with chronic conditions, those with conditions that weaken their immune system, and people who are unvaccinated.
Persons Who Have Been Exposed to COVID-19 (Close Contact) |
Recommended Action |
If you have been exposed to another person who has COVID-19, you do NOT have to quarantine if you do not have any symptoms. Exposed = Sharing the same indoor airspace for 15 minutes total over a 24-hour period. (Example: 3 different / 5-minute encounters equal a 15-minute exposure) A person who has COVID-19 can start to spread the virus 2 days before they start to develop symptoms (or 2 days before their positive test was taken, if they never develop symptoms) |
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Masking Guidance:
Wearing a well-fitting mask is essential to protecting others through 10 days after your infection starts or after your last exposure. For information on how to use masks most effectively, please refer to Get the Most out of Masking.
Frequently Asked Questions: Exposure to COVID-19 and Close Contacts of Someone with COVID-19 Infection
A person who is a close contact is at high risk for becoming infected with COVID-19. If they become infected, they might have symptoms or they might have no symptoms. If this happens, they could spread the virus to others, even without symptoms.
Additional Considerations for Settings Considered High-Risk for Severe COVID-19 Spread
- Please follow-up with your school to confirm your school’s guidance.
- Comprehensive Guidance – California State Department of Public Health (CDPH)
- Additional Resources – Alameda County Office of Education
- For additional information regarding schools & childcare guidance, please see: https://covid-19.acgov.org/schools
- Follow AFL 21-08 (or subsequent guidance from CDPH)
- Healthcare providers in other settings: Follow CDC Guidance
- Follow PIN 21-23-ASC (or subsequent guidance from CDSS)
- Follow AFL 22-13 (or subsequent guidance from CDPH)
- Definition of other high-risk settings (CDPH): A high-risk setting is one in which transmission risk is high (e.g., setting with a large number of persons who may not receive the full protection from vaccination due to co-existing medical conditions), and populations at risk of more serious COVID-19 disease consequences including hospitalization, severe illness, and death.
- Employees and residents in these setting should follow recommendations from State Guidance
- Follow recommendations (currently Page 3) of ACPHD Health Officer Order for Quarantine
- In circumstances where State or Federal laws apply (including workplace safety regulations), Alameda County guidance, recommendations, and Health Officer Orders do not supersede, override, or modify those laws.
COVID-19 Treatments and Medicine:
If you have or think you have COVID-19, there are prescription pills (and outpatient antibody infusions) available that can help reduce symptoms. They provide protection from hospitalization and death from COVID-19. The costs of these medications are free, but they must be started within a few days after symptoms begin. Don’t wait until symptoms get worse before talking with a healthcare provider.- Please see our page on medications and treatment for COVID-19.
- If you have questions about COVID treatment options, please contact our Treatment Inquiries Line (510-268-2101 | ncov@acgov.org): English | Spanish | Traditional Chinese
Health Officer Orders:
- Blanket Isolation Order (Order No. 20-05g – In effect 1/10/2022): English
- Blanket Quarantine Order (Order No. 20-06s - In effect 7/1/22): English
Home Isolation Guidance Packets:
Please follow the isolation guidance in the packet below for people who have tested positive for COVID-19 and their household or close contacts. You may be contacted by a member of the contact tracing team.
- Isolation Guidance Packet with Resources:
Note (6/29/22): These packets are currently being revised. Page 2, regarding quarantine is no longer applicable. Please follow close contact recommendations above. Isolation guidance (page 1) and resource lists (pages 3-4) are current.(updated 2022.04.4): English
(updated 2022.01.14): Arabic | Burmese | Traditional Chinese | Dari | Farsi | Hindi | Khmer | Korean | Mongolian | Pashtu | Punjabi | Spanish | Tagalog | Tigrinya | Vietnamese
Travel Guidance
When can I be around others after having COVID-19?
- Employees and students who are not ill do not need a doctor’s note to return to work or school after completing their isolation or quarantine period. We are receiving communications that this is happening, which is impacting the medical system and preventing doctors from seeing patients who are ill.
- When You Can be Around Others After You Had or Likely Had COVID-19 (CDC): English | Spanish│Chinese│Korean│Vietnamese
- Open Letter to Employers Regarding Clearance Testing
Note: this document includes quarantine language that is outdated as of 6/29/2022. Paragraphs about isolation for people infected with COVID-19 and resource web-links are accurate. This document will be updated soon. Please review close contact guidance above or in the Health Officer Order.(updated 2202.01.31): English | Arabic | Burmese | Chinese (Simplified) | Dari | Farsi | Hindi | Khmer | Korean | Mongolian | Pashtu | Punjabi | Spanish | Tagalog | Tigrinya | Vietnamese
- When You Can be Around Others After You Had or Likely Had COVID-19 (CDC): English | Spanish│Chinese│Korean│Vietnamese