How Long Does It Take Before COVID-19 Symptoms Surface?
There is usually an incubation period for infectious diseases – that is, the time from exposure to a pathogen and the appearance of symptoms. Scientists are still trying to understand this more as it pertains to the current novel coronavirus.
Around when the outbreak of SARS-CoV-2 was made public for the first time, it was revealed that infected individuals would start noticing the symptoms any time within the first 14 days of exposure.
The early estimates were informed by the events observed at the time. Past outbreaks of other types of coronaviruses also played a role.
Experts now know that it may take longer for a patient to show symptoms. In rare cases, an infected person might even carry the virus and be able to transmit it without showing symptoms.
About the coronavirus
Identified on Dec. 31 last year, the novel coronavirus was initially called the “Wuhan virus” after the Chinese city where it was first reported. Its name was later changed to 2019-nCoV and finally to SARS-CoV-2.
The virus causes COVID-19 disease, which produces symptoms such as respiratory problems, fever, and cough.
This disorder has since gone beyond the borders of China and continues to spread in other countries. According to estimates, there are now over 114,000 cases of infection worldwide.
Antarctica is currently the only continent where infection with the virus has yet to be reported.
Scientists are still trying to figure out where the SAR-CoV-2 emanated from. The consensus theory appears to be that it came from a wild animal. Coronaviruses typically move from animals to humans.
Some researchers have said that the virus possibly came from bats, going by a comparison of its genetic sequence with a database of virus. However, bats were not sold at the Wuhan seafood market where it seemed to start from.
Scientists are now considering the hypothesis that another animal, possibly pangolins, served as the vehicle for transmission to humans.
When do symptoms show?
Early observations led to the conclusion that symptoms of COVID-19 should appear between one and 14 days after exposure, according to the Centers for Disease Control and Prevention (CDC). Knowledge of similar viruses, such as SARS-CoV and MERS-CoV, also influenced the estimation.
The World Health Organization stated that most patients will start displaying symptoms from around five days after infection.
However, a review paper published in the JAMA recently suggests that it might take more than three weeks for symptoms to show. This means the incubation period that is currently accepted by most experts could still change.
There are also people who do not show any symptoms, although this is less common. According to the CDC, more than half of the 705 total cases on the cruise ship Diamond Princess did not show any symptom.
Experts say that asymptomatic individuals may, however, develop symptoms eventually.
Scientists do not know fully yet whether infected persons are highly contagious during the incubation period. But there are already reports of people transmitting the COVID-19 virus without showing symptoms.
Furthermore, research shows that some patients tested positive for the virus up to two weeks after they stopped showing symptoms.
There is no cure for the COVID-19 disease yet. Scientists are trying to repurpose existing drugs for the treatment of patients for now.