Leaky international cordon may mean equivalent of worst flu season in modern times
- Alvin Powell
The number of confirmed cases of the Wuhan coronavirus have continued to surge inside China, sickening tens of thousands, with a death toll of more than 1,000. But outside the Asian giant the numbers remain a fraction of that, a trend Harvard’s Marc Lipsitch views with suspicion. Lipsitch thinks it is just a matter of time before the virus spreads widely internationally, which means nations so far only lightly hit should prepare for its eventual arrival in force and what may seem like the worst flu season in modern times. Lipsitch, professor of epidemiology at the Harvard T.H. Chan School of Public Health and head of the School’s Center for Communicable Disease Dynamics, talked to the Gazette about recent developments in the outbreak and provided a look ahead.
GAZETTE: We spoke about the Wuhan coronavirus outbreak about a week and a half ago. What do we know now that we didn’t know then?
LIPSITCH: We know that the spread is even greater than it was then. It was likely then that it would spread more widely, but there was still hope for containment. I think now that it’s in more countries — even Singapore, which is really good at tracing cases, has found some cases that aren’t linked to previous known cases — it’s clear that there are probably many cases in countries where we haven’t yet found them. This is really a global problem that’s not going to go away in a week or two.
GAZETTE: You indicated that the rapid increase in cases was largely due to existing cases that hadn’t been diagnosed rather than new infections. Is that still your sense, or is some of the daily increase in cases due to new transmission?
LIPSITCH: It’s clearly partly due to new transmission — and it was partly due to new transmission then. Separating out reporting delays from new transmission is hard, but over the last few days, it appears that the rate of increase in new cases in China has slowed relative to the exponential growth we saw before. Some people are cautiously hopeful that that’s due to the success of control measures rather than the inability to count many cases. I think that’s possible, since the control measures have been rather extreme in some places. So, now the question is whether these control measures are working or whether we’re mostly seeing a saturation in their ability to test thousands of cases.
GAZETTE: When we talk about control measures, I think the one that’s most obvious to people who are following this are the quarantines. Are there other things going on that are also important?
LIPSITCH: For the cutting off of Wuhan, cordon sanitaire is probably a better word for it because the movement restrictions apply to everybody, not just the exposed people. They’re not exactly quarantined. Then there’s the quarantine of people who are sick and may or may not have the coronavirus, along with the isolation of people who have the coronavirus. All of that may be helping. We’ve had some concerns based on news reports that the way they’re doing the bulk quarantine and isolation of cases could be harmful in China, but it’s very hard to get a clear answer on what exactly is being done. The early reports said that they were taking people who were confirmed corona cases and putting them together in mass quarters with people who were not confirmed as corona but might have a fever or respiratory symptoms. If that was true, that could spread the virus further. Since then, I’ve heard a number of times that that’s not actually true. So I don’t know what to think of that. It doesn’t seem like the sort of thing a responsible public health agency would do.
GAZETTE: Has it become apparent that the virus is either easier to transmit or more deadly than previously thought? Or are these increasing case and fatality numbers in line with what our thinking was a week ago?
LIPSITCH: The ease of transmission is still being confirmed. In terms of the so-called “R-nought,” or how many secondary cases a single case infects, experts’ assessment is getting tighter around a level of transmissibility that’s perhaps lower than SARS, which was about 3 and higher than pandemic flu, which can be up to about 2. But what makes this one perhaps harder to control than SARS is that it may be possible to transmit before you are sick, or before you are very sick — so it’s hard to block transmission by just isolating confirmed cases. …