- How to get free home tests
- Which test? (brief overview)
- Where to get free COVID-19 tests in the East Bay
- Home rapid antigen testing
- Which test? (more details)
- The science behind when and which test to use
How to get free rapid home tests
You can now request 4 free rapid antigen home COVID tests mailed to your address at Covidtests.gov. The US postal service will fulfill orders and send the tests to your address in 7-12 days.
People with insurance can also get reimbursed for purchasing up to 8 rapid antigen tests per person per month. Purchases can be made online, at stores or pharmacies. Receipts are required to request reimbursement. More information about this new national policy can be found here. Please go to your health insurance’s website or contact them for details on how to request reimbursement.
Which test? (brief overview)
- Do a rapid test to get timely results and check your level of infectiousness. If needed, you can also do a PCR test to diagnose or rule out COVID-19. Both tests will pick up Omicron, Delta and other variants, whether you are vaccinated or not.
- Timing matters: a rapid test will give you timely information to act upon. A rapid test will tell you if you are infectious (with a high viral load) within 15-30 minutes. Rapid antigen tests are useful for screening for infectiousness right before a gathering (ideally 15-30 minutes before) as well as 3-5 days after an exposure and for screening every 3-5 days.
- Rapid tests accurately pick up Omicron infections with high viral loads.
- A PCR test will pick up much lower levels of virus for diagnostic and rule-out purposes but can take 1-4 days to get a result. By the time you get the result, the person’s most infectious period may be over.
- It’s important to wear a high quality mask and distance while waiting for test results, especially if you have symptoms.
Where to get free COVID-19 tests in the East Bay
COVID testing is supposed to be available without cost to you. You don’t need to have insurance or immigration papers. If you’re worried about getting billed or don’t have insurance or papers, we recommend getting tested at one of the county sites below. PCR tests using nose swab or using saliva (no swabs!) and rapid antigen tests are available.
- SF Chronicle’s map of Bay Area COVID testing sites that don’t require a doctor’s referral.
- Alameda County free COVID testing sites: This webpage includes community-based sites offering free testing for anyone with symptoms, including people without health insurance.
- Contra Costa County free drive-through or walk-in COVID testing
- Solano County free testing sites
- Home rapid antigen home testing is also available: click to read more
- Please check the listing for updates and call the testing site before you leave to make sure they are open for testing, you are eligible, and register if needed.
- If you don’t have a provider and have COVID symptoms: In Alameda County, call Alameda Health System 510-437-8500 for a phone screen and guidance. In Contra Costa County, call 844-729-8410. In Solano County, the county COVID warmline is 707-784-8988.
- If you’re having difficulty breathing and unstable, please go to your nearest emergency room.
Rapid antigen home tests
- The rapid antigen home COVID-19 tests detect viral nucleocapsid proteins and provide rapid results in 10-30 minutes for when people are at their most infectious stage. They are effective at picking up high viral loads and are less sensitive than the PCR tests but provide timely results and are cheaper and easier to use. These tests will pick up Omicron, Delta and other variants.
- Rapid tests are especially useful for screening right before a gathering. Ideally, do the rapid test 15-30 minutes before the gathering. This is because the Omicron and Delta variants spread very rapidly and when people don’t have symptoms.
- If you have an exposure, we recommend that you use the rapid antigen test to check for infectiousness 2-5 days after the exposure.
- Omicron appears to results in symptoms sooner, about a day or two after exposure, so it’s important to start isolating and test as soon as you feel symptoms.
- Omicron also appears to replicate rapidly first in the throat before the nose, so some countries (like the UK) and some people have been swabbing their throats before swabbing their noses for the rapid antigen tests (though it’s off-label use since this has not been authorized by the FDA/CDC in the US yet).
- Do not use a cotton swab (Q-tip) for rapid tests! The material in cotton swabs interfere with the test result. Only use the swabs that come with the kits and are intended for rapid testing.
- Antigen tests are more accurate with repeat testing every 2-5 days after an exposure.
- The BinaxNow, Ellume, Quidel QuickVue and Inteliswab COVID-19 antigen home tests are the most widely available; more are listed on the FDA website. These tests are done with a nasal swab, with results showing in 10-30 minutes on a card or little area of the device, like a home pregnancy test.
- Pricing for some home rapid tests have been discounted starting in September with the new US COVID-19 plan. For example, the BinaxNow and Inteliswab antigen home self-tests can now be purchased at $14 for 2 tests (discounted from the retail price of $23.99) at pharmacies and online retailers, such as at Amazon, Kroger and Wal-Mart.
- There are plans for health insurance companies to reimburse people for these tests, but this benefit will be limited to people who have health insurance, and it’s unclear when/how this will be enforced.
- The CDC has guidance on self-testing and what people should do with test results.
Which test should I get? More details:
- If you have symptoms, get a rapid test (and if needed, PCR test). A rapid test gives you timely results, and a positive rapid result is accurate for diagnosis. A PCR test diagnoses or rules-out COVID-19 with lower levels of virus if you have a negative rapid antigen test.
- Keep in mind that PCR test can take several days to get results, so stay home and isolate while you’re waiting for results.
- Combining a PCR test and a rapid antigen test can both provide diagnosis as well as screen for current infectiousness.
- A positive rapid antigen test result can quickly diagnose a COVID-19 infection with high viral loads. However, if a rapid antigen test is negative, you still need a PCR test to check for lower levels of virus and confirm a negative result.
- Rapid antigen tests have the highest sensitivity for infections in people in their first week of symptoms.
- If a PCR test is not available, repeat the antigen test every 2-5 days for 14 days to confirm the negative result.
- If you are screening for infectiousness and/or 2-5 days after an exposure, a rapid antigen test can quickly identify infectiousness with high viral loads, including in asymptomatic infection and in vaccinated people.
- People with SARS-CoV-2 infections are typically infectious 1-2 days before symptoms start, and some people do not develop noticeable symptoms (they remain asymptomatic) even when they are infectious.
- Rapid antigen tests have a 95% overall sensitivity for PCR cycle thresholds (Ct) below 25, which indicate higher viral loads.
- For delta infections, viral loads are typically highest (PCR Ct <25) in the first 3 to 14 days after exposure.
- After an exposure, test 3-5 days after the exposure and then repeat the rapid antigen test every 3-7 days for 14 days to confirm the negative result if you don’t get a PCR test.
- Screening every 3-7 days increases the sensitivity and chance the rapid antigen test will pick up someone who is infectious, even before symptoms and if they don’t develop symptoms. That way people know to stay home and curb the spread.
- Remember that a negative test result doesn’t mean you can stop other preventive measures. Getting vaccinated, wearing a mask, distancing and screening are all used in combination to get the delta variant under control.
The science behind COVID-19 PCR and antigen testing
Testing and Omicron: listen to this In the Bubble podcast with Dr. Michael Mina and Andy Slavitt to hear Dr. Mina’s expert responses to listener questions around testing and the Omicron variant.
For the delta variant, emerging data indicates that the infectious stage likely begins sooner (2-3 days) and lasts longer (13-18 days). See references below. Rapid antigen testing will be most likely to pick up delta infections starting 3-5 days after exposure and up to about 14 days after exposure in unvaccinated people or about 11 days after exposure in vaccinated people.
Frequent rapid antigen testing every 3-7 days is more likely to catch a delta infection during the infectious period than less frequent PCR testing. Rapid antigen tests are also less likely than PCR test to pick up people who are no longer infectious but are still shedding viral particles. The more frequent the rapid antigen testing (2 times a week or more), the more likely you will detect infectiousness before a person becomes symptomatic or spreads the virus. Frequency of testing is balanced between willingness to test, cost ($10-15 per test in the US), availability and access.
Rapid antigen screening every 3 or 7 days for delta infections
This table illustrates hypothetically how different frequencies of rapid antigen testing (every 3 or 7 days) might detect delta infections during the most highly infectious period (2-18 days after exposure). This table shows how we are more likely to catch infections earlier during the most infectious period with testing every 3-4 days (twice a week) rather than every 7 days (once a week). The green plus symbols (+) show days when infection is caught and the red “O” or exclamation marks (O or !) show days when infection might be missed.
- The dashes (-) mark when the rapid antigen test is performed, is negative, and may be too soon to be in a period of infectiousness.
- The question marks (?) mark when the rapid antigen test is performed, is negative, and we do not have enough data to know if it’s likely to be a day of high infectiousness.
- The red exclamation points (!) mark when the rapid antigen test is not performed because of the testing schedule and thus miss the infection during a likely infectious day.
- The red O’s (O) mark when the rapid antigen test is performed and may miss the infection (pre-symptomatic PCR Ct and viral loads not yet known).
- The green pluses (+) mark when the rapid antigen test is performed and more likely pick up the infection (viral loads expected to be high and PCR Ct expected to be <25).