In the age of the coronavirus, recommendations from scientists can change quickly. Although the changes can be frustrating to the public, the Centers for Disease Control and Prevention (CDC) makes these changes based on scientific evidence as best as they can.
Since April 2020, the CDC recommended a 14-day quarantine for people who have mild to moderate symptoms of COVID-19 (without a test). This quarantine also applied to people who may have traveled from somewhere with high coronavirus case numbers. In April, researchers believed that with COVID-19, 97% of the people who got infected showed symptoms within 11 to 12 days. Most people (99%), they believed, showed symptoms within 14 days. Therefore, they placed a 14-day guideline.
4. The New Evidence
The new evidence, according to the CDC, shows that people are no longer infectious 10 days after the onset of symptoms and after fevers have stopped for 24 hours. This new guideline allows patients to come out of isolation without having to get a negative COVID-19 test.
According to the CDC, most people with COVID-19 can come out of isolation:
- 10 days after symptoms start, as long as they have no fever for 24 hours without the help of medications that lower fevers. Their symptoms must be improving.
- For those who test positive but don’t show any symptoms, isolation can be stopped 10 days after their first positive coronavirus test.
The virus that causes COVID-19, SARS-CoV-2, is a new virus. Unlike the flu or the measles, scientists haven’t had decades to study SARS-CoV-2. There’s been less than half a year of good data to work off of. Yet, the world counts on the research at every step. This means that researchers have needed to quickly revise guidelines according to their most recent findings. Their research is done in order to keep the public safe.
3. Why the CDC Is Making These New Recommendations
The CDC’s evidence for the changes is as follows:
- The amount of virus found in the respiratory system declines after coronavirus symptoms start.
- Research shows that in patients with mild to moderate COVID-19 symptoms, the virus has not been found after 10 days following the start of symptoms. Although in severe COVID-19 patients, viruses that can infect can be found between 10 and 20 days after symptoms start, these patients tend to have compromised immune systems. Even in these patients, about 88% and 95% had no viruses that can cause COVID-19 after 10 and 15 days following the start of their symptoms.
- In a contact tracing study, high-risk households and hospital contacts didn’t develop any infections if they were exposed six days after a case patient’s symptoms began to show.
- Although viruses can still be found 12 weeks after symptoms start, these viruses were not found to be able to cause COVID-19 in others. This shows how some people can be consistently positive and still not infect others.
- Patients who re-developed symptoms and test positive for the virus did not have viruses that could cause COVID-19 in others.
- Even after six months of research, there have been no confirmed cases of SARS-CoV-2 reinfection that can be found.
- Proof of immunity has not been found yet. Scientists do not know how long people can stay immune.
The CDC provides the following case studies that may go against their new changes; however, these events are rare. The CDC also discloses a few caveats that could affect their guidelines.
- In a study of healthcare workers in one facility who were followed to see if they had no symptoms but were infected, only one of 48 infected staff had a positive test 20 days after first testing positive for COVID-19.
- A person with mild coronavirus symptoms had viruses that could infect others for up to 18 days after the start of their first symptom.
- More data are needed from children and infants regarding their ability to infect others.
- More data are needed from immunocompromised patients in regard to viral shedding.