SARS-CoV-2 Is Re-emerging Following the Relaxation of Lockdown Restrictions

In many countries, after weeks or months of tight COVID-19 lockdown restrictions, governments and officials have been gradually relaxing the rules, allowing certain sectors to resume operations and social interaction to take place on some level.

Currently, we are still some way from an effective, safe and readily-available vaccine. Infection rates have also not been as high as one may have expected at the start of the outbreak, even in areas considered “hotspots” like New York, likely in part due to lockdown measures that have prevented soaring case numbers from overwhelming health services. Certainly, no areas have been identified where infection has been as high as the estimated 60 % infection rate required to confer herd immunity, a point that is still debated. However, in the absence of either of these scenarios, it does mean that we still lack any form of herd immunity in the global population, leaving many vulnerable to SARS-CoV-2 infection.

This therefore begs the question of what happens next? Is there a second wave of infection coming, can we predict this and what should be done about it? As we consider these points, it is pertinent to look at how the situation in China is unfolding.

Coronavirus in Beijing – isolated outbreak or a second wave of infection?

Both China and New Zealand had declared themselves “coronavirus free” by mid-June; however, this victory has been short-lived and highlights the ongoing need for caution. In New Zealand, two women were prematurely released from quarantine on compassionate grounds, only later to test positive.

A cluster of cases emerged in Beijing last week, leading to the re-introduction of restrictions for the local population. As with the original outbreak in Wuhan this has been linked to a food market. Brendan Wren, Professor of Microbial Pathogenesis at the London School of Hygiene & Tropical Medicine, said “Beijing had previously gone 57 days without a locally-transmitted case of COVID-19 and the latest peak in the number of cases is a real concern.” As more cases continued to emerge (137 over past six days) and it became clear the outbreak was not under control, China took the decision to once again ground hundreds of flights, raise the emergency level and prevent non-essential travel.

Whilst in the case of New Zealand, the source is known and appears to have been contained, the scenario in China is raising concern. Wren continued “It will be important to establish the source of this re-infection, it is likely to be locally-transmitted through human transfer, but given that the origin of the infection was in China we shouldn’t exclude the possibility of the original animal source suspected from food markets being responsible for the latest outbreak. DNA sequencing of the virus from infected individuals should establish a forensic trail to establish the source and reservoir of this re-infection.”

Some initial reports in Chinese local media following human and environmental testing had suggested a link to the import or packaging of salmon. Given what we know about SARS-CoV-2 infectivity, this seems unlikely to be the primary source, and is more feasibly a result of cross-contamination. Speaking at a press conference on Monday, Dr Michael Ryan, Head of the World Health Organization’s (WHO) emergencies program, was keen to stress [in relation to a link to salmon] that “I think we need to look at what has happened in this case, I don’t believe it is the primary hypothesis. But it needs to be explored.” He continued “As we’ve seen in many countries, the emergence of new clusters – especially when the origin of the cluster, the driver of the cluster, is not recognized – is always a concern.”

Considering the source of this new outbreak in Beijing, Keith Neal, Emeritus Professor of the Epidemiology of Infectious Diseases at the University of Nottingham, commented “What is actually happening in China is never truly transparent so only informed guesses are possible. Beijing have been using compulsory enforced quarantines for all returning travelers. If people are tested at the end of their 14 day quarantine, and given that no test is 100% sensitive, and with 1000s of people returning, an infected person(s) was/were always going to slip through these controls. This is person to person or person to environment to person spread; possibly focused on a market as in Wuhan. Salmon as a source is highly unlikely - how did the salmon get COVID? Given comments about feces in the market, food hygiene might be very poor.”

Whether situations like this constitute a second wave of infection or something more localized depends on how you view the scenario. Neal concluded “This is not a second wave but a localized outbreak. It does depend on how you define a second wave though. Re-emergence is going to be an on-going issue and also note what has happened in New Zealand with international travel.” Whatever your definition, what is clear is that this is an ongoing problem that is not going away any time soon and vigilance and control measures will remain of key importance.

What are the implications for the rest of the World?

As we watch on from countries around the World, the current situation in China should serve as a warning. Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician at Liverpool School of Tropical Medicine, said “The COVID-19 outbreak in Beijing serves as a reminder that, despite the UK having passed through the first wave of COVID-19, we still remain in the early stages of the pandemic.” This situation is echoed around the globe with some countries not yet thought to have reached the peak of the first wave of cases.

Wingfield continued: “In the absence of herd immunity through either an effective vaccine or immunity following infection, the majority of the population – both in the UK and globally – remains at risk of COVID-19 if exposed to SARS-CoV-2. It is inevitable that there will continue to be outbreaks, even in countries with very low numbers of COVID-19 cases per day such as China.”

National and international responses are key

Techniques such as wastewater monitoring and ongoing testing are likely to be important factors in identifying and “fire-fighting” new incursions as they crop up for the foreseeable future.

“Swift and coordinated responses to such outbreaks at regional, national, and international levels will be key to breaking transmission and preventing further spread of the virus. These responses are likely to include targeted testing and tracing and reinstatement of lockdown measures such as social distancing and travel restrictions. It is also likely that rather than being a blanket national policy, responses will instead be focused on specific hotspot areas affected by outbreaks.” concluded Wingfield.

As even hard-hit countries like Italy throw open their borders and re-instate tourist activities in the hope of stimulating much needed income, it should be considered at what human cost and do these actions just prolong the problem?

As cases continue to be identified across China, testing is being ramped up and restrictions tightened in the hope of containing further spread. At least with the wealth of research development that has happened since the initial outbreak in Wuhan, scientists, epidemiologists and officials are better armed to tackle the problem.