Harvard epidemiology professor estimates up to 60 percent of adults will get infected
Marc Lipsitch, a professor of epidemiology at Harvard T.H. Chan School of Public Health in Boston (Stephanie Mitchell/Harvard University News Office)
South Korea is the country with the highest number of confirmed cases of the new coronavirus outside China, accounting for about 6.9 percent of the 105,586 infections worldwide.
Since the first case was reported Jan. 20, Korea has tested 196,618 people and confirmed 7,382 cases, according to the latest official tally published Monday. Its death rate stands at 0.7 percent.
In discussing some of the most frequently asked questions about the new virus, Harvard epidemiology professor Marc Lipsitch told The Korea Herald that “the data from Korea, once analyzed, will be of great global value in helping to understand these important questions.”
“Korea, more than any other country, has had opportunities to understand the full spectrum of severity, because of very extensive testing of individuals exposed in various outbreaks,” he said in an e-mail interview.KH:
Healthy young adults have died of COVID-19, which is known to be deadlier in elderly people. How does the disease affect different age groups?Lipsitch:
It is not unusual for infectious diseases to have more severe outcomes in older people, but also occasionally to lead to death of a younger person who appears healthy. We don’t know the cause of these unusual deaths in younger people. Perhaps they had a health problem that was not known and made them more at risk. Perhaps they were exposed to a larger dose of the virus. Or perhaps there was some chance factor we haven’t understood. This is fairly typical.KH:
Are children spared from the virus?Lipsitch:
Children do not get detectable infection at the same rate as adults, especially severe infection, but they may get infection and may transmit -- we just don’t know. KH:
Is it true that for the vast majority of people, the virus will pass like a common cold and they will never know they’ve had it?Lipsitch:
I don’t think we yet know that. There are many people, especially young people, for whom this infection is mild. I don’t think there are any published data yet on the full spectrum of cases. But good news is even in the Chinese first 44,000 cases published by the China CDC, more than 80 percent were defined as mild. That may be more than a common cold, but not severe.KH:
Is it possible that COVID-19 is incurable -- even if symptoms improve and a patient is deemed “cured,” the disease recurs when the immune system weakens?Lipstich:
I don’t think this has been documented. It is possible for viral diseases that are normally acute (short-term) to become chronic (longer-term) in people with compromised immune systems. There has been at least one report of someone becoming “cured” and then shedding virus again, but the most likely explanation there is that the patient had not really been cured, just happened to have one or more negative tests (false negatives, or no virus on the swab but the virus is still in the body).KH:
Will COVID-19 never go away, but become a seasonal illness like the flu? If so, will we end up developing herd immunity, at which point the virus won’t be as lethal?Lipsitch:
It is possible. If that happens, we can hope -- and it is reasonable, though not guaranteed -- that most people will have enough immunity after one exposure that they do not get severe disease, even if they get infected again. KH:
Are we looking at the worst pandemic of this century? What are the estimated infection and death tolls?Lipsitch:
It looks like this will be worse than 2009 influenza, the only other true pandemic of the century. I estimate that 20-60 percent of adults will get infected, though not all will be symptomatic. Estimates I trust are that between 1-2 percent of symptomatic people die. That may come down a little as we define symptoms more broadly (milder symptoms). The problem with giving an overall number is that to calculate a number, we need to multiply the proportion of these two estimates times the proportion of infected who are symptomatic (unknown) times the population size.KH:
When do you predict the epidemic will peak -- here in Korea and globally?Lipsitch:
This is very hard to predict for many reasons -- not knowing the true number infected, which affects the peak time, and also not knowing what kinds of control measures will be applied, which will reduce the number of people and delay the peak.KH:
Critics say anxiety about the virus is excessive, and worry it will hurt the economy. Should virus containment be our top priority right now, and should other considerations (i.e., the economy) be second?Lipsitch:
It has to be a balance, but disease control is a very high priority. If people are able to get basic necessities and the economy and society to function well enough to keep people alive and healthy (mentally as well as physically) then disease control should take precedence. This seems to be happening for example in Hong Kong and Singapore. But it depends on the ability of a society to function well enough while reducing social contacts.
By Kim Arin (firstname.lastname@example.org