Jul 29, 2021 06:48 PM

Zhang Wenhong: Will Nanjing’s Outbreak Grow Out of Control?

Zhang Wenhong, director of China’s National Center of Infectious Diseases. Photo: VCG
Zhang Wenhong, director of China’s National Center of Infectious Diseases. Photo: VCG

The pandemic’s spread from Nanjing to other provinces recently has become a new transmission pattern of imported Covid-19 cases in China. China is implementing strict pandemic prevention and control measures and promoting vaccination, but the virus is still spreading. This is making the public anxious about the future — an anxiety rising from the uncertainty of what lies ahead.

Will Nanjing’s outbreak grow out of control?

The pandemic’s spread in Nanjing follows the rule of “point-linear-dispersion.” Taking Nanjing Lukou International Airport as the outbreak point, the pandemic has spread from the airport to other domestic provinces and cities along flight routes, and most Covid-19 cases in other provinces and cities have been discovered among key groups related to the airport. In provinces and cities outside of Nanjing, there is no big spread of Covid-19 originating from any source other than Nanjing Lukou International Airport, which indicates that the outbreak is still controllable.

If there are no more second-generation and third-generation Covid-19 cases in other provinces and cities in the coming one or two weeks, this particular flare-up will be limited to Nanjing.

As for the situation in Nanjing, the spread has mainly been caused by family gatherings attended by people who were infected at the Nanjing Lukou International. Although there are many airport-related Covid-19 cases in the Lukou subdistrict, there are not many untraceable community cases in other areas of Nanjing. This tells us that Nanjing is in the early phase of a large-scale spread in communities. At present, Nanjing has taken strict measures to prevent and control the outbreak. If these measures are effective, the situation could be brought under control within a few weeks. We should feel confident that it can be done. The pandemic monitoring in the next one or two weeks will be crucial. If more Covid-19 cases with no direct correlation to Nanjing Lukou International are found, it means that the scale of the spread has expanded and that we need to take more decisive measures.

At the moment, we need to be calm, carefully implement the strategy for pandemic prevention and control and carry out nucleic acid testing in one area after another. By doing this, we will get through the most critical moment.

The outbreak in Nanjing once again puts the vaccines’ effectiveness in question

People who have been vaccinated can still be infected, which has been proven by the outbreaks in Nanjing and Guangzhou. However, there could have been even more cases if people had not been vaccinated.

Ultimately, to know how effective the vaccines have been will require reliable global and domestic data. Currently, the vaccination rate in the U.K. and Israel is nearly 70%. Although the number of infected people has increased recently because of the relaxation of quarantine restrictions, it will no longer cause a lack of medical resources, and the fatality rate has gone down from 18% (highest rate last year) to 0.1% for last week. The latter is close to the fatality rate of a normal flu.

In other words, in a short period of time, we could lower the harm of Covid-19 to the level of the seasonal flu by establishing population immunity through vaccination. If we did not have a vaccine, we could eventually learn to live with the virus by gradually building up herd immunity, but it would take decades and come at a huge cost.

Are Chinese vaccines effective? The recently completed continuous observation of inactivated vaccines on the market in Chile is medically known as a real world study. The observation data have been published in the New England Journal of Medicine, the most famous medical journal in the world. It was a tough test.

From Feb. 2 to May 1 this year, Chile assessed the protective effect of the Chinese inactivated vaccines used in the country. The vaccinated cohort included 10.2 million Chileans. Among the people vaccinated with two doses, the effectiveness of the Chinese inactivated vaccines in preventing coronavirus infection was 65.9%, and the rates for protection against hospitalization, ICU occupancy and death were 87.5%, 90.3% and 86.3% respectively.

The results of vaccination in Chile show that the Chinese inactivated vaccines are highly effective in preventing Covid-19 cases from severe exacerbation, hospitalization and death. At present, vaccines can have a certain protective effect in slowing down transmission and reducing mortality, but they are not strong enough to eradicate the disease.

The data tell us that even if each of us were to be vaccinated in the future, Covid-19 would still be endemic, but at a lower level with a lower fatality rate. After the liberalization of vaccines, there will still be infections in the future, all countries will have to reduce Covid-19’s mortality rate and spread through vaccination while further raising citizens’ awareness of prevention and control measures. The prevention and control efforts of national public health systems (including hospitals and disease control and prevention institutions) will also need to be intensified. If we do this, we can eventually “live in harmony” with the virus.

The need for wisdom of long-term coexistence with the virus

There is a growing belief that we will not see the end of the outbreak in the short term, maybe not even in the long term. Most virologists worldwide agree that this is a resident virus and the world will have to learn to coexist with it.

The latest outbreak in Nanjing once again reminds us of the ever-present virus. Whether we like it or not, there will always be risks in the future. Each country is trying to find its own answer to the question — how will the world be able to live with the virus. China has already provided a satisfactory answer and after the outbreak in Nanjing, we will certainly be able to learn more. China’s choice will be a coping approach that ensures a shared future for mankind, helps realize the world connectivity and promotes a return to normal life while protecting its citizens from fear of the virus. This is wisdom that China should have.

Zhang Wenhong is director of National Center of Infectious Diseases and director of Infectious Diseases Department of Huashan Hospital affiliated to Fudan University.

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