Federal health officials on Monday issued revised recommendations for the general public on what to do if they test positive or are exposed to someone who tested positive for COVID-19. 

In the weeks prior, the government also changed return-to-work guidance for health care workers, as well as students and school staff, resulting in three separate sets of instructions on what to do after COVID exposure or infection. 

The recommendations reflect the latest science from studies conducted around the world, officials said during a Wednesday press briefing. 

“We are standing on the shoulders of two years of science, two years of understanding transmissibility and a lot of information that we have gleaned from the wild-type virus, as well as the alpha and delta variants and more that we continue to learn every single day about omicron,” CDC director Dr. Rochelle Walensky said in part. 

Early data has now sufficiently shown that the omicron variant of COVID-19 is highly transmissible, but may not lead to as severe disease as previous variants. Caseloads in the United States have skyrocketed in recent weeks, and while hospitalizations and deaths from COVID have not increased quite as fast, those numbers tend to lag several weeks behind case increases. 

Federal health officials stress that the best way to protect yourself from the virus, including the omicron strain, is to get a booster vaccination. While breakthrough cases are still possible, boosted individuals have a lower chance of experiencing extreme illness and hospitalization.

Here are the government recommendations to mitigate the spread of COVID-19 as the pandemic heads into its third year: 

The CDC's recommendations for those exposed to COVID-19 depend entirely on an individual’s vaccination status. The guidance is for "close contacts" of someone with COVID, which the agency defines as being within six feet of a confirmed positive case for 15 minutes or more over a 24-hour period.

For individuals who have received a booster shot – or who completed either the two-dose Moderna or Pfizer vaccine regimen within the last six months, or the single-dose Johnson & Johnson shot in the past two months – no isolation is needed after exposure to COVID-19. 

Those individuals should, however, wear a mask around all individuals for 10 days after exposure, and take a COVID-19 test five days after their known exposure. 

Unvaccinated individuals and those who have not yet gotten a booster shot – and who do not fall within the two-month J&J window or the six-month Pfizer or Moderna window – should quarantine for five days following their exposure, and wear a mask around others for an additional five days after quarantine. 

If quarantine isn’t possible, individuals should wear a mask around all other people for 10 days after their exposure to COVID-19, and should also take a test five days after exposure. 

“If at any point you develop symptoms of COVID-19 during your quarantine period, or your ten days after exposure, like fevers, runny nose or cough, headaches, body aches, you should get a test and isolate until your test results return,” Dr. Walensky said Wednesday. “And of course, then isolate if your test returns positive.”

Those who test positive for COVID-19 – whether via PCR or antigen test – must immediately enter isolation.

Regardless of an individual’s vaccination status, those who test positive should remain in isolation for at least five days after receiving the results of their test. 

That’s because the virus is most transmissible in the one to two days before symptoms develop, and the two to three days after. Between 85% and 90% of viral transmission occurs in those first five days. 

During isolation, individuals should wear a mask while around other people (even within the household) in order to “avoid spreading the virus at home,” per CDC director Dr. Rochelle Walensky. 

If individuals are asymptomatic or if symptoms have “largely resolved” after those five days, a person may leave isolation so long as they continue to wear a mask for an additional five days, including around their home. 

The CDC does not require individuals to take a PCR test after their isolation period, as “people can remain PCR-positive for up to 12 weeks after infection and long after they are transmissible or infectious.” 

The CDC is also still studying how effective antigen tests are in detecting transmissibility at this stage of infection.

“Even if you had a negative [antigen] test, we would want you to mask, and even if you had a positive [antigen] test, we would also want you to,” Walensky told reporters Wednesday. “And therefore, given that the U.S. antigen tests are not authorized for use in this way, we do not recommend them.” 

The CDC’s recommendations for school staff and students is slightly more stringent than those for the general public, likely due to the enclosed setting of many classrooms. 

Unvaccinated individuals who come into contact with COVID-19, but do not display any symptoms, should quarantine at home for 14 days. If an original test comes back negative, another should be performed five to seven days after exposure. Even if the second test is negative, students and staff should complete the full two-week quarantine period. 

There are also several options to shorten quarantine to 10 days or even seven, based on “local circumstances and resources,” per the CDC.

Quarantine can end on day 10 without testing if an individual has presented no symptoms since exposure; quarantine can also end on day seven should an individual have exhibited no symptoms and received a negative COVID-19. The latter option should only be used if “diagnostic testing resources are sufficient and available” in the surrounding community. 

In late December, the CDC opted to also endorse test-to-stay policies for students and school staff, a system intended to prevent children exposed to COVID-19 from unnecessarily disrupting their education. The announcement essentially said test-to-stay policies are just as effective as the previously-endorsed quarantine strategy. 

The test-to-stay policy only applies to asymptomatic, unvaccinated or not fully vaccinated individuals who came into close contact with COVID-19 positive individuals at school, as there is no quarantine requirement for those with booster vaccinations. 

Contact tracing and serial testing – or tests that are repeated over the period of several days – are integral components of the test-to-stay policy. If a student or staff member either tests positive or begins experiencing symptoms, they should not go to school and should begin their isolation period. 

Serial testing must take place on non-consecutive days, the first of which should be administered within two to four days of exposure, and the second within five to seven days after exposure. Individuals are considered out of the test-to-stay period if they receive at least one negative test result between day five and seven, or after ten days with no symptoms. 

Health officials have repeatedly stressed that test-to-stay policies are most effective when paired with all other recommended mitigation strategies, such as universal indoor masking, social distancing, hand-washing, proper ventilation and serial testing. 

All school staff and students, regardless of their vaccination status, must immediately isolate following a positive COVID-19 test result even if they are asymptomatic, or as soon as they start to experience symptoms. 

A student or staff member diagnosed with COVID-19 should isolate for at least 10 days after experiencing symptoms, or 10 days after the date of their first positive test, if they are asymptomatic. Individuals must also have had no fever for at least 24 hours with improved symptoms before returning to school. 

Those guidelines do not apply to immunocompromised individuals, who should consult with an expert before returning to school or work.

Return-to-work guidance for health care personnel is broken down even further than that for schools and the general public, as it varies based on what type of PPE the individual(s) were wearing at the time of the exposure, vaccination status and the overall hospital worker needs. 

“The CDC is updating our materials to help schools and parents know how to best implement this promising – and now proven – practice, along with our multilayered prevention strategies that will help keep our children in the classroom safely,” Walensky said at the time. 

The first set of recommendations are for workers at higher risk of contracting the disease after exposure – i.e. if the worker had “prolonged close contact” with a COVID-19 individual and if the worker was not wearing proper protective gear. 

For fully boosted health care personnel, there are generally no return-to-work restrictions. But individuals should test themselves for COVID no less than 24 hours after their exposure, and if negative, again at five to seven days after contact.

For unvaccinated workers or those who have not yet received a booster despite being eligible, there are two options: Do not return to work until seven days after exposure, pending a negative viral test, or they can wait 10 days and return to work should they remain asymptomatic.

All exposed healthcare personnel at high risk of contracting COVID-19 should follow infection protection strategies after exposure, and should closely monitor for the appearance of any symptoms.

Individuals at low risk of contracting the disease – i.e. those who wore proper PPE and followed mitigation protocols – have no work or testing restrictions, but should monitor for symptoms and not return to work should they develop.

Under normal conditions, when a hospital or healthcare center is not experiencing a worker shortage and does not expect to in the near future, there are a few different recommendations based on severity of the illness and underlying health conditions. 

Healthcare personnel with mild to moderate symptoms and who are not immunocompromised can return to work should they meet three criteria. 

Individuals can return to work seven days after a positive test, should they get a negative antigen or NAAT test within 48 hours of returning to work, or 10 days after infection if no tests were performed since symptoms first appeared. Workers should also wait at least 24 hours after their last fever  before returning to work, and when symptoms such as a cough or shortness of breath have faded. 

Healthcare personnel who were infected but remained asymptomatic, and who are not immunocompromised, need only to meet the first criteria listed above.

Healthcare personnel with severe COVID-19 infections, and who are also not immunocompromised, can typically return to work when 20 days have passed since symptoms first appeared; when at least 24 hours have passed since their last fever; when symptoms have improved and who have received at least two negative results from COVID-19 tests taken 24 hours apart. 

Immunocompromised individuals may produce the virus beyond 20 days after infection, and should use both a test-based strategy as well as consult with an infectious disease specialist before returning to work.