Ja and 24 Kovid-19 marks a moment in the history of the epidemic but the anniversary of a largely unnoticed event: the first published report of a person infected with the novel coronavirus who never developed symptoms. This early confirmation of asymptomatic infection set off the alarm bell and changed our response to the deeply collected storm. but that did not happen. A year later, we are paying the price for this horrific explosion.
At least one in three people infected with SARS-CoV-2, which causes the virus Kovid-19, does not develop symptoms. This is the conclusion of a review that we have published in Annals of Internal Medicine. It summarizes the results of 61 studies with more than 1.8 million people.
But during much of the epidemic, fierce resistance – and even outright denial – led to ineffective testing practices in accepting this nonspecific disease pattern, which allowed the epidemic to spin out of control.
On January 28, 2020, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, stated, “In the history of any type of respiratory-borne virus, asymptomatic transmission has never been the driver of an outbreak. … even That if there is a rare asymptomatic person that can transmit, an epidemic is not driven by asymptomatic carriers. “
It was a widely held scene. On June 8, 2020, a senior World Health Organization official called asymptomatic transmission “very rare”.
To his credit, Fauci was among those who immediately criticized the remark. Based on epidemiological data that had become available since his earlier observations, he said that marking asymptomatic transmission as anomalous was “not correct”.
In June, when we published a report of 16 colleagues with a large proportion of asymptomatic infections and suggested that it might play a role in the progression of the epidemic, several researchers wrote letters to the editor demanding that our paper be withdrawn Go
Today, the best evidence suggests that about half of Covid-19 cases are caused by infected people who do not have symptoms when they have the virus. These symptom-free broadcasters are broadly divided between those who develop symptoms later, known as pre-symptomatic individuals, and those who never develop symptoms.
While the importance of asymptomatic infections in understanding Kovid-19 has been surprising to some, infectious pathologists have long known that infections without symptoms are common in many diseases. More than 90% of people infected with polio virus have no symptoms. And approximately 75% of influenza infections have been estimated to be asymptomatic. Yet these important examples have largely been ignored.
Asymptomatic coronovirus infection is not necessarily benign. Numerous studies have reported abnormal scans of infected lungs without symptoms, as well as myocarditis, a type of heart inflammation. The long-term health implications of asymptomatic infection are not known.
Although knowledge about asymptomatic infection has developed greatly, there is no strategy to deal with the epidemic. It is now clear that testing only with symptoms, as was common in epidemics, is a mistake because it ignores the invisible legends of infected people who have no symptoms. But this is not enough to simply increase the number of tests. The problem is that current testing practices are ill equipped to detect and contain asymptomatic infections.
Virtually all polymerase chain reactions (PCRs) of coronovirus testing conducted in the US look for the genetic material of the virus. This requires expensive equipment and trained technicians. Results are usually returned after testing – sometimes on weekdays. This means that people are aware that they have been infected with SARS-CoV-2, as long as they can pass the virus on to others. Testing becomes more about accounting – reducing the number of infections detected, compared to the spread of the virus.
What is needed is a spindle for a different type of test. Antigen tests, which look for a bit of coronovirus protein, each cost a few dollars and can get results in minutes. Like home pregnancy tests, they require minimal instructions. Antigen tests are ideal for identifying those who are infectious, rather than those who may live longer than the infectious phase of Kovid-19, or who bother such low levels of the virus that they infect others Are unlikely to.
Cheap rapid home tests will help infected people isolate themselves before spreading the virus. Continuous testing – at least several times per week – is required, as demonstrated by successful testing efforts at some universities, which have enabled students to return to campus. A new focus on self-help, in combination with financial assistance and perhaps temporary housing for isolation, will directly address the problem of asymptomatic infection.
The rollout of Kovid-19 vaccines threatens a new wave of asymptomatic infections. Two vaccines authorized by the Food and Drug Administration have been proven to prevent the disease, but not asymptomatic infections. Even after vaccination, the coronovirus can reside temporarily in the lining of the respiratory tract, making it possible to infect others. Preliminary results from a vaccine trial seem encouraging, with a two-thirds reduction in asymptomatic infection after the first dose. But many other studies are underway.
There is no time machine that allows us to return until January 24, 2020, and plans that we should have made that acknowledge the importance of the asymmetric transition. But it is not too late to spot the blame and move aggressively toward testing practices that will help end the epidemic.
Daniel P. Oran is a member of the Digital Medicine Group at the Scripps Research Translational Institute, of which Eric J. Topol is the founder and director.