Professor David Heymann, advisor to the WHO on Covid-19, says there are many unknowns about the disease, but valuable lessons too.
The one constant that has characterized Covid-19 is uncertainty. With some big epidemiological questions unanswered, we are struggling to predict the destiny of the virus. Will Covid-19 disappear as fast as it arrived, or will it become endemic, like seasonal influenza? Will catching it provide immunity or will it, like the dengue fever viruses, be more severe the second time around? Without a sensitive antibody test, we cannot be certain about community spread. We also do not fully understand the clinical spectrum. With 80 percent of symptoms being mild and around 9 percent of cases showing no symptoms, we do not know why some otherwise healthy people succumb, and some with underlying health conditions get away with mild symptoms.
Professor David Heymann
For Professor David Heymann, a veteran of disease outbreaks, the gaps in our knowledge are troubling. He is currently chair of the independent advisory group to the WHO on Covid-19 and led the global response to SARS in 2003. Some of the decisions taken by governments to protect their citizens worry him. His biggest surprise is the speed and severity with which societal lockdowns came into force “With no certainty about a vaccine it is wrong for countries that have locked down to say that they will now keep the reproductive level low until there is a vaccine, it is the wrong hypothesis. The way forward is to do everything you can to keep the virus at a level you feel your country can sustain.” The big unknown is whether we will come up with an effective vaccine. Heymann believes there is no guarantee we will.
“My fear is that many countries have entered these lockdowns without a clear exit strategy,” he says. He points to Sweden, much maligned initially but now attracting growing interest as an example of allowing the virus to enter in a controlled manner. Sweden has implemented rules around gatherings and restaurant seating distances, but has adopted a bottom-up approach to containment by trusting the population to act responsibly. Asian countries such as South Korea and Vietnam have also successfully avoided total societal lockdowns while still managing to stem transmission. Heymann feels political decisions were driven by an unfortunate sequence of events over the first three months of the outbreak.
My fear is that many countries have entered these lockdowns without a clear exit strategy
The Chinese lockdown of Wuhan appeared to be working at the time that Italy’s healthcare system became ravaged by the virus. Other governments did not want to take the risk of letting that happen to their countries and wanted to be seen to take firm action. What remained unclear as the lockdowns were introduced was the impact on social inequality. “Especially those who live hand to mouth and then lose their day-to-day employment. In many instances they are also the ones with comorbidities which I find extremely concerning as an epidemiologist,” he says.
100 % of those infected
Another unknown about Covid-19 is why it initially appears to be disproportionately affecting the developed world. There are a number of theories in play around travel interconnectivity, the low average age of those in developing countries, and that it may be too early to tell what the full impact will be. “It is possible all these are working together, and we will see different epidemiology in different parts of the world,” says Heymann. While there is a lot to be concerned about with Covid-19, one of the most encouraging responses has been the level of global technical cooperation, which belies some of the geopolitical tensions at the top levels of government. Heymann points to cooperation between the Chinese and American centers of communicable disease. “As chair of the independent advisory group to the WHO program, I have access to all this information and it really is quite amazing how freely data is being shared,” he says. He also recognizes the way scientific journals are allowing open source access and the speed at which research is being peer reviewed as a critical tool in trying to contain the virus.
In my role for the WHO, I have access to all of this information, and it really is quite amazing how freely data is being shared.
In mid-May, as many countries in the West were trying different methods to release citizens from lockdown, Asia started to go in the opposite direction. “They are introducing what you could call circuit breakers, where they introduce a lockdown for a few weeks or months and then remove it. An example is Hong Kong, which shut down its nightlife for a couple of weeks,” says Heymann. As the pandemic develops, unanswered questions will be resolved and, with the comfort of time, we will be better able to assess which epidemiological approach is best suited to which circumstances. One of the bittersweet benefits of a global pandemic is that, ultimately, it will provide many different models from which to learn how to combat future diseases.