Covid ‘zero’ and a second wave of infections
Wuhan, the city in Central China that was the epicenter of the coronavirus disease 2019 (Covid-19), reported zero confirmed coronavirus domestic infection cases on March 17. It kept the zero status from that day onward until press time on March 20. The city and the country’s experience are markedly different from the rest of the world — China was the sole epidemic center in January and February. Then many countries started to experience an upsurge of infection at the end of February. By March 20, Covid-19 hit more than 150 countries and territories all over the world with more than 275,000 reported cases and 11,000 dead.
Wuhan’s and China’s experience served as a beacon of hope of containment as a possibility at this uncertain time. They proved that a combination of quarantine effort to cut transmission route, aggressive testing to sort out the non-symptomatic infectious carrier and mobilizing hospital facilities to relieve pressure on the healthcare system could effectively control the disease. The approach has won over the traditional containment and epidemiological tracing method as their advanced countries’ proponents move to lockdown, aggressive testing and giving up ideas of relying on herd immunity.
There is now widespread public support to take the unprecedented draconian measures of lockdown, curfews, extensive school suspension and home working. The public realized that what happens is necessary for controlling the disease. Still, some quarters have raised fears that these measures will only succeed to stem the first wave of infection, and it is not worth it to extend these measures after the first round of implementation.
The detractors cited the case of the “Spanish flu” of 1918. The flu combines avian and swine flu genes with that of humans, and infected an estimated 500 million people with 50 million dead. The world population was only 2 billion at the time. The infection rate of 25 percent of humanity and the mortality rate of 10 percent was the worst in modern history.
The viral illness underwent three distinct phases. The first phase started in January 1918, slowly rising and peaking in July. It got into a lull but reappeared in the October-December period. This second wave was the most virulent; the peak mortality rate was five times that of the first round. The flu virus then got a two-month respite. The third wave came in February-May; the peak mortality rate in this period was less than half of the second round.
The immunological knowledge at the time of the Spanish flu was primitive; there were no active measures such as a vaccine to protect the uninfected [clean] population, test to ferret out silent carriers or epidemiology record to cut off transmission route. The second and third waves happened because the only means of protecting the population relied on natural induced antibody herd immunity protection developed by the population-based daily low-level exposure to flu antigens in the air. The herd immunity takes time to develop, and it is slow in dealing with a virulent disease challenge.
The science on virus and disease has grown by leaps and bounds in the last 100 years. Chinese scientists isolated the virus in less than a week after receiving the patient sample, and they published the gene sequence in less than two weeks. Hence, the world developed many test kits to segregate an infected patient in less than three weeks. It is the first time the world can cut the transmission route based on precise identification of the infected patient in such a short time.
The significance of zero cases is that it indicates an absence of active human carrier in the population. Eliminating human carriers in the group means the only sources of reactivation of a viral second-wave rebound are either environmental contamination and imported case.
With the higher temperature in summer helping to keep aerosol coronavirus low, vigilant environment cleanup and a continuation of strict entry monitoring of imported human traffic, it is possible that the countries successfully implementing the proven control paradigm mentioned earlier can eliminate Covid-19 with no fear on second wave rebound of the disease.
One should remember that the inherent low-level coronavirus challenge in the air would activate specific immunity in the population at a low level over time. There are more than 20 vaccines under development now, but they will take more than one year or so to put into commercial use at best. The job of the government now is to hold the transmission at bay and cut down the number of active cases. We don’t need to hit zero before we can put life back to normal. Going into next year, the chance of a commercial vaccine to protect people is good.
The experience with the severe acute respiratory syndrome (SARS) in 2003 serves as a good case in point. The countries affected by SARS just saw a complete halt of SARS infection when they stopped the human transmission in the summer of 2003.
What people experience today is painful, and yet we saw the virus can be controlled. Keep up vigilance and implement the World Health Organization recommendation: TEST, TEST, TEST!
Dr. Henry Chan is an internationally recognized development economist based in Singapore. He is also a senior visiting research fellow at the Cambodia Institute for Cooperation and Peace and adjunct research fellow at the Integrated Development Studies Institute (IDSI). His primary research interest includes global economic development, Asean-China relations and the Fourth Industrial Revolution.
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**Also published in: https://www.manilatimes.net/2020/03/29/opinion/columnists/covid-zero-and-a-second-wave-of-infections/707704/