Upto 25% people infected with coronavirus may not show symptoms, warns CDC as it reviews use of masks
As many as 25% of people infected with the new coronavirus may not show any symptoms, according to the US Centers for Disease Control and Prevention (CDC). This is a significant number which may pose as a major challenge in containing the COVID-19 pandemic and predicting its course going forward.
“One of the (pieces of) information that we have pretty much confirmed now is that a significant number of individuals that are infected actually remain asymptomatic. That may be as many as 25%. That's important, because now you have individuals that may not have any symptoms that can contribute to transmission, and we have learned that in fact, they do contribute to transmission,” CDC Director, Dr Robert Redfield, said during an interview with Atlanta-based WABE, which is affiliated to the National Public Radio (NPR).
He further said, “Of those of us that get symptomatic, it appears that we're shedding significant virus in our oropharyngeal compartment, probably up to 48 hours before we show symptoms. This helps explain how rapidly this virus continues to spread across the country because we have asymptomatic transmitters and we have individuals who are transmitting 48 hours before they become symptomatic.”
A previous study from China had said that people infected with the new coronavirus may not even know they are carrying the disease since there might be no visible symptoms. Another study estimates that 86% of all infections were undocumented in China before travel restrictions were put in from January 23. It said the high proportion of undocumented infections, many of whom were likely not severely symptomatic, appears to have facilitated the rapid spread of the virus throughout China.
CDC reconsiders guidelines on who should wear masks
Based on this 25% number, Dr Redfield said the CDC is reviewing past recommendations that encouraged the general public not to wear masks if they are not sick.
“We're always critically looking at new data and ... there is data from obviously Singapore, Hong Kong, and China that looks at the issue and you can look at masks in two ways. Is the mask something that protects me or ... if I wear a mask, is it something that protects others, from me,” he said.
Dr Redfield explained, “Particularly with the new data, that there's significant asymptomatic transmission, this is being critically re-reviewed to see if there's potential additional value for individuals that are infected or individuals that may be asymptomatically infected. Obviously you can see the complexity of that, if you assume that 25% are asymptomatic, the only way you would do it — if you then sort of went into areas that were high transmission zones and had a significant (proportion of) individuals then wearing masks, assuming that they were infected. I can tell you that the data and this issue of whether it's going to contribute (to prevention) is being aggressively reviewed as we speak.”
According to the current CDC guidelines, if a person is not sick, they do not need to wear a facemask unless they are caring for someone who is sick (and they are not able to wear a facemask). Facemasks may be in short supply and they should be saved for caregivers, says the CDC.
“If you are sick, you should wear a facemask when you are around other people (for example, sharing a room or vehicle) and before you enter a healthcare provider’s office. If you are not able to wear a facemask (for example, because it causes trouble breathing), then you should do your best to cover your coughs and sneezes, and people who are caring for you should wear a facemask if they enter your room,” the guidelines state.
The health expert reiterated that Americans should practice aggressive social distancing, as it is a “powerful weapon.”
Overpreparing, not under preparing in healthcare
Dr Redfield emphasized that what the coronavirus outbreak has illustrated is that the US should be overinvesting in public health, overpreparing not under preparing.
“I don't think anybody would disagree that for decades, collectively, our nation's underinvested in public health. Now, I think people understand that that can really have significant consequences, and now is the time for us to overinvest overprepare in public health,” he said.
Dr Redfiled also said that the virus is “going to be with us.” “I'm hopeful that we'll get through this first wave and, and have some time to prepare for the second wave. I'm hopeful that the private sector in its ingenuity and working with the government, NIH, will develop a vaccine that ultimately will change the impact of this virus,” he said.
He added, “But for the next 24 months, you know, we're all in this together and the most important thing that we can do is twofold: the American public fully embracing the social distancing that we requested to protect the vulnerable; and secondly, to operationalize the bread and butter of public health — you know, early case identification, isolation, contact tracing — so that this outbreak does not get the upper hand, as it has, unfortunately, in New York City, in northern New Jersey, and now New Orleans.”
Over 216,720 cases have been reported across the US, and over 5,000 have died, according to the John Hopkins tracker.